From 93d88ac4a448f200d18d1d71de0074b8e716bbee Mon Sep 17 00:00:00 2001 From: Tao Cui Date: Tue, 25 Aug 2026 10:35:56 +0800 Subject: sched_ext: Pass the initial cpu.idle state in scx_cgroup_init_args scx_cgroup_init_args carries the initial weight and bandwidth control parameters of a cgroup to ops.cgroup_init(), but not its cpu.idle state. A cgroup that was already configured idle before the scheduler was loaded (or before it was onlined under it) is presented as non-idle, and the BPF scheduler only learns about it if cpu.idle is written again later. Add the sched_idle state to scx_cgroup_init_args and fill it in all four places that build the args: scx_tg_online() for cgroups onlined under the scheduler, scx_cgroup_init() for cgroups that already exist when the scheduler is loaded, and the sub-scheduler handover paths scx_cgroup_claim_subtree() and scx_cgroup_return_subtree(). Verified in a VM with a probe scheduler printing the init args: a cgroup configured cpu.idle=1 before loading shows sched_idle=1 in ops.cgroup_init(), the default shows 0, and later cpu.idle writes still come through ops.cgroup_set_idle(). The sub-scheduler paths are compile-tested only. Fixes: 347ed2d566da ("sched/ext: Implement cgroup_set_idle() callback") Signed-off-by: Tao Cui Reviewed-by: Andrea Righi Signed-off-by: Tejun Heo --- kernel/sched/ext/ext.c | 4 +++- kernel/sched/ext/internal.h | 3 +++ kernel/sched/ext/sub.c | 2 ++ 3 files changed, 8 insertions(+), 1 deletion(-) (limited to 'kernel') diff --git a/kernel/sched/ext/ext.c b/kernel/sched/ext/ext.c index 713aa26b2828..901fb0f8b976 100644 --- a/kernel/sched/ext/ext.c +++ b/kernel/sched/ext/ext.c @@ -4766,7 +4766,8 @@ int scx_tg_online(struct task_group *tg) { .weight = tg->scx.weight, .bw_period_us = tg->scx.bw_period_us, .bw_quota_us = tg->scx.bw_quota_us, - .bw_burst_us = tg->scx.bw_burst_us }; + .bw_burst_us = tg->scx.bw_burst_us, + .sched_idle = tg->scx.idle }; ret = SCX_CALL_OP_RET(sch, cgroup_init, NULL, tg->css.cgroup, &args); @@ -5187,6 +5188,7 @@ static int scx_cgroup_init(struct scx_sched *sch) .bw_period_us = tg->scx.bw_period_us, .bw_quota_us = tg->scx.bw_quota_us, .bw_burst_us = tg->scx.bw_burst_us, + .sched_idle = tg->scx.idle, }; ret = SCX_CALL_OP_RET(sch, cgroup_init, NULL, css->cgroup, &args); diff --git a/kernel/sched/ext/internal.h b/kernel/sched/ext/internal.h index 0967b99a4948..076a351bb3f2 100644 --- a/kernel/sched/ext/internal.h +++ b/kernel/sched/ext/internal.h @@ -259,6 +259,9 @@ struct scx_cgroup_init_args { u64 bw_period_us; u64 bw_quota_us; u64 bw_burst_us; + + /* whether the cgroup is configured SCHED_IDLE via cpu.idle */ + bool sched_idle; }; enum scx_cpu_preempt_reason { diff --git a/kernel/sched/ext/sub.c b/kernel/sched/ext/sub.c index 0554448835bd..385302d19914 100644 --- a/kernel/sched/ext/sub.c +++ b/kernel/sched/ext/sub.c @@ -1361,6 +1361,7 @@ static s32 scx_cgroup_claim_subtree(struct scx_sched *sch) .bw_period_us = tg->scx.bw_period_us, .bw_quota_us = tg->scx.bw_quota_us, .bw_burst_us = tg->scx.bw_burst_us, + .sched_idle = tg->scx.idle, }; if (tg->scx.sched != parent || @@ -1464,6 +1465,7 @@ static void scx_cgroup_return_subtree(struct scx_sched *sch) .bw_period_us = tg->scx.bw_period_us, .bw_quota_us = tg->scx.bw_quota_us, .bw_burst_us = tg->scx.bw_burst_us, + .sched_idle = tg->scx.idle, }; /* the first pass must have transferred everything */ -- cgit v1.2.3 From 29871903f3a38e75e896f9a644713859490cb85f Mon Sep 17 00:00:00 2001 From: Tao Cui Date: Tue, 1 Sep 2026 20:43:47 +0800 Subject: sched_ext: Don't deliver duplicate ops.cgroup_set_idle() for same value ops.cgroup_set_idle() is documented to be invoked when a cgroup transitions between idle and non-idle states, and scx_group_set_weight() already skips value-preserving writes. scx_group_set_idle() delivers every write unconditionally, so rewriting an already-correct cpu.idle value feeds the BPF scheduler a transition callback each time, which toggle- or accounting-based schedulers miscount. Mirror the weight guard and only deliver on an actual change. Verified with a probe scheduler printing each callback: rewriting cpu.idle=1 twice on an already-idle cgroup delivered two callbacks before and none after. Fixes: 347ed2d566da ("sched/ext: Implement cgroup_set_idle() callback") Link: https://lore.kernel.org/r/b53c61a1-4d7d-4232-941f-d48b0563d4ed@linux.dev Signed-off-by: Tao Cui Reviewed-by: Andrea Righi Signed-off-by: Tejun Heo --- kernel/sched/ext/ext.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'kernel') diff --git a/kernel/sched/ext/ext.c b/kernel/sched/ext/ext.c index 901fb0f8b976..5f242ab69cf4 100644 --- a/kernel/sched/ext/ext.c +++ b/kernel/sched/ext/ext.c @@ -4933,7 +4933,8 @@ void scx_group_set_idle(struct task_group *tg, bool idle) percpu_down_read(&scx_cgroup_ops_rwsem); sch = scx_tg_knob_sched(tg); - if (scx_cgroup_enabled && sch && SCX_HAS_OP(sch, cgroup_set_idle)) + if (scx_cgroup_enabled && sch && SCX_HAS_OP(sch, cgroup_set_idle) && + tg->scx.idle != idle) SCX_CALL_OP(sch, cgroup_set_idle, NULL, tg_cgrp(tg), idle); /* Update the task group's idle state */ -- cgit v1.2.3 From 0a85182723b65ad8bee8131bc38fcf0347d6679b Mon Sep 17 00:00:00 2001 From: Wanwu Li Date: Thu, 3 Sep 2026 14:06:26 +0800 Subject: sched_ext: Fix NULL sched deref in kfunc sub-sched error paths When the root scheduler has sub-scheds attached, the COMPAT kfunc wrappers scx_bpf_select_cpu_and() and scx_bpf_dsq_insert_vtime() refuse the call and report to @p's scheduler: scx_error(scx_task_sched(p), "... must be used"); The wrappers are reachable with tasks that have no scheduler. scx_bpf_select_cpu_and() is in the select_cpu kfunc group, which scx_kfunc_context_filter() opens to BPF_PROG_TYPE_SYSCALL programs; scx_bpf_dsq_insert_vtime() is in the enqueue_dispatch group, which ops.enqueue() and ops.dispatch() may call with any KF_RCU task -- the group has no kf_tasks validation, and scx_dsq_insert_preamble() checks task ownership with scx_task_on_sched() precisely because @p may be an arbitrary task. scx_task_sched(p) is p->scx.sched, which is NULL for tasks past sched_ext_dead() -- which clears it via scx_disable_and_exit_task() on exit -- and for idle tasks, which the enable paths skip as they are never scheduled through SCX. It is also an rcu_dereference_protected() that expects @p's pi_lock or rq lock, which neither wrapper holds. Passing NULL to scx_error() reaches scx_vexit(), which dereferences sch->exit_info, oopsing the kernel. One concrete trigger exercised while developing the fix: a BPF_PROG_TYPE_SYSCALL program calling the select_cpu_and wrapper on an exited-but-not-reaped task while a sub-scheduler was attached (its pid stays findable while the zombie is unreaped; faulting instruction is the scx_vexit() prologue "mov r15,[rdi+0x398]" with RDI=NULL and 0x398 the offset of sch->exit_info): sched_ext: BPF scheduler "kfunc_subsched_null" enabled sched_ext: BPF sub-scheduler "kfunc_subsched_null" enabled sched_ext: Unassociated program run_select_cpu_ (id 76) BUG: kernel NULL pointer dereference, address: 0000000000000398 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page Oops: Oops: 0000 [#1] SMP NOPTI CPU: 7 UID: 0 PID: 8201 Comm: kfunc_test_runn Tainted: G W RIP: 0010:scx_vexit+0x25/0xa0 Code: ... <4c> 8b bf 98 03 00 00 ... CR2: 0000000000000398 Call Trace: __scx_exit+0x4f/0x70 scx_bpf_select_cpu_and+0xab/0xb0 bpf_prog_430ed61a7b66e03a_run_select_cpu_and+0x9c/0xe7 ? __x64_sys_bpf+0x2c/0x40 bpf_prog_test_run_syscall+0x130/0x2f0 __sys_bpf+0x930/0x10d0 ? __x64_sys_bpf+0x2c/0x40 __x64_sys_bpf+0x2c/0x40 do_syscall_64+0xbc/0x460 entry_SYSCALL_64_after_hwframe+0x76/0x7e Read @p's scheduler under RCU instead, which the wrappers can do from their guard(rcu)(): fault it when it can be determined, and when it can't be determined -- @p is a task past sched_ext_dead() or an idle task -- there is nothing obviously wrong to report, so just refuse the call as before without faulting any scheduler. These COMPAT wrappers are scheduled for eventual removal once the deprecation grace period elapses, but until then -- and regardless of their removal timeline -- they must not oops the kernel on a task they are handed. Cc: stable@vger.kernel.org # v7.1+ Fixes: a5fa0708cbfd ("sched_ext: Enforce scheduling authority in dispatch and select_cpu operations") Suggested-by: Andrea Righi Signed-off-by: Wanwu Li Signed-off-by: Tejun Heo --- kernel/sched/ext/ext.c | 11 +++++++++-- kernel/sched/ext/idle.c | 11 +++++++++-- 2 files changed, 18 insertions(+), 4 deletions(-) (limited to 'kernel') diff --git a/kernel/sched/ext/ext.c b/kernel/sched/ext/ext.c index 5f242ab69cf4..7e414a7c53fc 100644 --- a/kernel/sched/ext/ext.c +++ b/kernel/sched/ext/ext.c @@ -8949,10 +8949,17 @@ __bpf_kfunc void scx_bpf_dsq_insert_vtime(struct task_struct *p, u64 dsq_id, #ifdef CONFIG_EXT_SUB_SCHED /* * Disallow if any sub-scheds are attached. There is no way to tell - * which scheduler called us, just error out @p's scheduler. + * which scheduler called us, so error out @p's scheduler -- read it + * under RCU as @p's locks aren't necessarily held here. @p may be a + * task past sched_ext_dead() or an idle task, in which case its + * scheduler can't be determined and there is nothing obviously wrong + * to report; just refuse the call. */ if (unlikely(!list_empty(&sch->children))) { - scx_error(scx_task_sched(p), "__scx_bpf_dsq_insert_vtime() must be used"); + struct scx_sched *tsch = scx_task_sched_rcu(p); + + if (tsch) + scx_error(tsch, "__scx_bpf_dsq_insert_vtime() must be used"); return; } #endif diff --git a/kernel/sched/ext/idle.c b/kernel/sched/ext/idle.c index d2973fb3af6d..aa9fb6de0ad6 100644 --- a/kernel/sched/ext/idle.c +++ b/kernel/sched/ext/idle.c @@ -1142,10 +1142,17 @@ __bpf_kfunc s32 scx_bpf_select_cpu_and(struct task_struct *p, s32 prev_cpu, u64 #ifdef CONFIG_EXT_SUB_SCHED /* * Disallow if any sub-scheds are attached. There is no way to tell - * which scheduler called us, just error out @p's scheduler. + * which scheduler called us, so error out @p's scheduler -- read it + * under RCU as @p's locks aren't necessarily held here. @p may be a + * task past sched_ext_dead() or an idle task, in which case its + * scheduler can't be determined and there is nothing obviously wrong + * to report; just refuse the call. */ if (unlikely(!list_empty(&sch->children))) { - scx_error(scx_task_sched(p), "__scx_bpf_select_cpu_and() must be used"); + struct scx_sched *tsch = scx_task_sched_rcu(p); + + if (tsch) + scx_error(tsch, "__scx_bpf_select_cpu_and() must be used"); return -EINVAL; } #endif -- cgit v1.2.3 From 3265ef0b670180b0b946d73ee9825d6d91e98a08 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Sat, 5 Sep 2026 06:09:55 -1000 Subject: sched_ext: Rename sch to root_sch in dispatch_one() dispatch_one() uses the root scheduler for everything it does, including the two decisions to keep running @prev, which are wrong when @prev belongs to a sub-scheduler. The function has to deal with @prev's scheduler too. Rename the root's local from sch to root_sch for clarity and to make room for it. No functional change. Signed-off-by: Tejun Heo Reviewed-by: Andrea Righi --- kernel/sched/ext/ext.c | 16 ++++++++-------- 1 file changed, 8 insertions(+), 8 deletions(-) (limited to 'kernel') diff --git a/kernel/sched/ext/ext.c b/kernel/sched/ext/ext.c index 7e414a7c53fc..120540cdda74 100644 --- a/kernel/sched/ext/ext.c +++ b/kernel/sched/ext/ext.c @@ -2919,7 +2919,7 @@ static inline void maybe_queue_balance_callback(struct rq *rq) static enum scx_dsp_verdict dispatch_one(struct rq *rq, struct task_struct *prev) { - struct scx_sched *sch = scx_root_protected_live(); + struct scx_sched *root_sch = scx_root_protected_live(); enum scx_dsp_verdict verdict; s32 cpu = cpu_of(rq); @@ -2928,7 +2928,7 @@ static enum scx_dsp_verdict dispatch_one(struct rq *rq, struct task_struct *prev scx_process_sync_ecaps(rq, prev); - if ((sch->ops.flags & SCX_OPS_HAS_CPU_PREEMPT) && + if ((root_sch->ops.flags & SCX_OPS_HAS_CPU_PREEMPT) && unlikely(rq->scx.cpu_released)) { /* * If the previous sched_class for the current CPU was not SCX, @@ -2936,8 +2936,8 @@ static enum scx_dsp_verdict dispatch_one(struct rq *rq, struct task_struct *prev * core. This callback complements ->cpu_release(), which is * emitted in switch_class(). */ - if (sch->ops.cpu_acquire) - SCX_CALL_OP(sch, cpu_acquire, rq, cpu, NULL); + if (root_sch->ops.cpu_acquire) + SCX_CALL_OP(root_sch, cpu_acquire, rq, cpu, NULL); rq->scx.cpu_released = false; } @@ -2955,7 +2955,7 @@ static enum scx_dsp_verdict dispatch_one(struct rq *rq, struct task_struct *prev * test. */ if ((prev->scx.flags & SCX_TASK_QUEUED) && prev->scx.slice && - !scx_bypassing(sch, cpu)) { + !scx_bypassing(root_sch, cpu)) { verdict = SCX_DSP_PREV; goto has_tasks; } @@ -2967,7 +2967,7 @@ static enum scx_dsp_verdict dispatch_one(struct rq *rq, struct task_struct *prev goto has_tasks; } - verdict = scx_dispatch_sched(sch, rq, prev, false); + verdict = scx_dispatch_sched(root_sch, rq, prev, false); if (verdict != SCX_DSP_NONE) goto has_tasks; @@ -2976,9 +2976,9 @@ static enum scx_dsp_verdict dispatch_one(struct rq *rq, struct task_struct *prev * %SCX_OPS_ENQ_LAST is in effect. */ if ((prev->scx.flags & SCX_TASK_QUEUED) && - (!(sch->ops.flags & SCX_OPS_ENQ_LAST) || scx_bypassing(sch, cpu)) && + (!(root_sch->ops.flags & SCX_OPS_ENQ_LAST) || scx_bypassing(root_sch, cpu)) && scx_task_can_stay_on_cpu(rq, prev)) { - __scx_add_event(sch, SCX_EV_DISPATCH_KEEP_LAST, 1); + __scx_add_event(root_sch, SCX_EV_DISPATCH_KEEP_LAST, 1); verdict = SCX_DSP_PREV; goto has_tasks; } -- cgit v1.2.3 From 90f19b2816f5d243a8daf36ca83d9d9d04f00e4c Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Sat, 5 Sep 2026 06:09:56 -1000 Subject: sched_ext: Use @prev's scheduler for the keep decisions in dispatch_one() dispatch_one() tests ops flags and bypass state against the root scheduler in both places where it decides to keep running @prev: the early keep of a @prev with slice left tests the root's bypass state, and the keep-last at the end tests the root's SCX_OPS_ENQ_LAST and bypass state. Both are properties of the scheduler @prev belongs to, and put_prev_task_scx(), which acts on the outcome, reads them from that scheduler. When @prev belongs to a sub-scheduler the two sides disagree. The keep-last case is visible. The root set SCX_OPS_ENQ_LAST, so a lone @prev of a sub-scheduler is not kept and is enqueued with SCX_ENQ_LAST to a sub-scheduler that never opted in. This trips the WARN_ON_ONCE in put_prev_task_scx() for the missing flag, and the sub-scheduler queues the task like any other and triggers no follow-up scheduling event, which can lead to stalls. Test SCX_OPS_ENQ_LAST and bypass state on @prev's sched in both places and charge SCX_EV_DISPATCH_KEEP_LAST to it. Read the sched at each decision, as the dispatch in between can drop the rq lock. Fixes: 88234b075c3f ("sched_ext: Introduce scx_task_sched[_rcu]()") Signed-off-by: Tejun Heo Reviewed-by: Andrea Righi --- kernel/sched/ext/ext.c | 23 ++++++++++++++--------- 1 file changed, 14 insertions(+), 9 deletions(-) (limited to 'kernel') diff --git a/kernel/sched/ext/ext.c b/kernel/sched/ext/ext.c index 120540cdda74..adf5993fa597 100644 --- a/kernel/sched/ext/ext.c +++ b/kernel/sched/ext/ext.c @@ -2955,7 +2955,7 @@ static enum scx_dsp_verdict dispatch_one(struct rq *rq, struct task_struct *prev * test. */ if ((prev->scx.flags & SCX_TASK_QUEUED) && prev->scx.slice && - !scx_bypassing(root_sch, cpu)) { + !scx_bypassing(scx_task_sched(prev), cpu)) { verdict = SCX_DSP_PREV; goto has_tasks; } @@ -2972,15 +2972,20 @@ static enum scx_dsp_verdict dispatch_one(struct rq *rq, struct task_struct *prev goto has_tasks; /* - * Didn't find another task to run. Keep running @prev unless - * %SCX_OPS_ENQ_LAST is in effect. + * Didn't find another task to run. Keep running @prev unless its own + * scheduler set %SCX_OPS_ENQ_LAST and takes the enqueue instead, see + * put_prev_task_scx(). Read the scheduler here as the dispatch above + * may have dropped the rq lock while @prev changed class or scheduler. */ - if ((prev->scx.flags & SCX_TASK_QUEUED) && - (!(root_sch->ops.flags & SCX_OPS_ENQ_LAST) || scx_bypassing(root_sch, cpu)) && - scx_task_can_stay_on_cpu(rq, prev)) { - __scx_add_event(root_sch, SCX_EV_DISPATCH_KEEP_LAST, 1); - verdict = SCX_DSP_PREV; - goto has_tasks; + if (prev->scx.flags & SCX_TASK_QUEUED) { + struct scx_sched *prev_sch = scx_task_sched(prev); + + if ((!(prev_sch->ops.flags & SCX_OPS_ENQ_LAST) || + scx_bypassing(prev_sch, cpu)) && scx_task_can_stay_on_cpu(rq, prev)) { + __scx_add_event(prev_sch, SCX_EV_DISPATCH_KEEP_LAST, 1); + verdict = SCX_DSP_PREV; + goto has_tasks; + } } rq->scx.flags &= ~SCX_RQ_IN_DISPATCH; return SCX_DSP_NONE; -- cgit v1.2.3 From 504981db4f69bdd28054fb98c96a3a67f7248dde Mon Sep 17 00:00:00 2001 From: Donggeun Yoo Date: Sat, 5 Sep 2026 16:47:27 +0900 Subject: dma-coherent: report a failed reserved memory assignment rmem_dma_device_init() drops the return value of dma_assign_coherent_memory() and always reports success. That call fails with -EBUSY when the device already has a coherent pool, and the file allows only "*one* such region of memory" per device. of_reserved_mem_device_init_by_idx() reads the zero as success. It logs "assigned reserved memory node" for a region that was not assigned and records the pairing, so of_reserved_mem_device_release() later runs rmem_dma_device_release() for it. That clears dev->dma_mem without looking at which region it was called for, dropping the pool the device did get and leaving it on ordinary memory. dma_declare_coherent_memory() checks the same call and releases the memory on failure, and rmem_swiotlb_device_init() propagates its own errors. Return the error here as well, so a device tree that assigns two pools to one device fails the probe instead of half working. Fixes: 7bfa5ab6fa1b ("drivers: dma-coherent: add initialization from device tree") Signed-off-by: Donggeun Yoo Link: https://lore.kernel.org/r/20260905074727.108029-1-donggeunyoo.kernel@gmail.com Signed-off-by: Marek Szyprowski --- kernel/dma/coherent.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) (limited to 'kernel') diff --git a/kernel/dma/coherent.c b/kernel/dma/coherent.c index 45bbae947f4b..4d0266893bcc 100644 --- a/kernel/dma/coherent.c +++ b/kernel/dma/coherent.c @@ -352,8 +352,7 @@ static int rmem_dma_device_init(struct reserved_mem *rmem, struct device *dev) min_not_zero(dev->coherent_dma_mask, dev->bus_dma_limit)) dev_warn(dev, "reserved memory is beyond device's set DMA address range\n"); - dma_assign_coherent_memory(dev, mem); - return 0; + return dma_assign_coherent_memory(dev, mem); } static void rmem_dma_device_release(struct reserved_mem *rmem, -- cgit v1.2.3 From b7d7914a9ae3097e63d113007e4fb44d33d515b1 Mon Sep 17 00:00:00 2001 From: Donggeun Yoo Date: Sat, 5 Sep 2026 17:42:10 +0900 Subject: swiotlb: use the adjusted address for the highmem page lookup swiotlb_bounce() reads the page frame number from the slot's recorded orig_addr, then advances orig_addr by tlb_offset to reach the address the caller asked about. The highmem branch mixes the two: the offset within the page comes from the adjusted address, the page from the value before it. Once the adjustment crosses a page boundary the pair no longer describes one location, and the whole copy lands one page below the intended one for a positive tlb_offset, one above for a negative one. DMA_FROM_DEVICE writes the device data over the wrong page and leaves the intended one stale, DMA_TO_DEVICE feeds the device from a page the mapping may not cover. Partial syncs through dma_sync_single_range_for_*() are what make tlb_offset non-zero. The branch test is picked the same way, so a slot recorded in lowmem can be adjusted into highmem and the lowmem path then hands a highmem address to phys_to_virt(). Take both from orig_addr once it is final and keep pfn in the branch that uses it. PhysHighMem() asks the question straight from the address, as dma-debug already does. Fixes: 5f89468e2f06 ("swiotlb: manipulate orig_addr when tlb_addr has offset") Cc: stable@vger.kernel.org Signed-off-by: Donggeun Yoo Reviewed-by: Michael Kelley Link: https://lore.kernel.org/r/20260905084210.148255-1-donggeunyoo.kernel@gmail.com Signed-off-by: Marek Szyprowski --- kernel/dma/swiotlb.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'kernel') diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c index ded7016a46a7..aa2f1c4588b9 100644 --- a/kernel/dma/swiotlb.c +++ b/kernel/dma/swiotlb.c @@ -1019,7 +1019,6 @@ static void swiotlb_bounce(struct device *dev, phys_addr_t tlb_addr, size_t size int index = (tlb_addr - mem->start) >> IO_TLB_SHIFT; phys_addr_t orig_addr = mem->slots[index].orig_addr; size_t alloc_size = mem->slots[index].alloc_size; - unsigned long pfn = PFN_DOWN(orig_addr); unsigned char *vaddr = mem->vaddr + tlb_addr - mem->start; int tlb_offset; @@ -1052,7 +1051,8 @@ static void swiotlb_bounce(struct device *dev, phys_addr_t tlb_addr, size_t size size = alloc_size; } - if (PageHighMem(pfn_to_page(pfn))) { + if (PhysHighMem(orig_addr)) { + unsigned long pfn = PFN_DOWN(orig_addr); unsigned int offset = orig_addr & ~PAGE_MASK; struct page *page; unsigned int sz = 0; -- cgit v1.2.3 From 88ce88e933e40f4ab4b81a5e9d0a10328583f593 Mon Sep 17 00:00:00 2001 From: Daniel Borkmann Date: Thu, 10 Sep 2026 23:35:07 +0200 Subject: bpf: Add KF_PERFMON kfunc flag Tracing related BPF helpers e.g. under bpf_base_func_proto() are gated behind CAP_PERFMON. However, the same is currently not true for kfuncs and they are accessible via plain CAP_BPF. Add a new KF_PERFMON flag which can be used such that check_kfunc_call() ensures env->allow_ptr_leaks is permitted. This follows similar pattern to existing KF_DESTRUCTIVE flag. The rejection returns -EPERM to match the other CAP_PERFMON gates in the verifier, that is, check_ptr_to_btf_access() and check_ptr_to_map_access(), which report the very same policy to user space. Signed-off-by: Daniel Borkmann Link: https://lore.kernel.org/r/20260910213510.49358-1-daniel@iogearbox.net Signed-off-by: Alexei Starovoitov --- kernel/bpf/verifier.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+) (limited to 'kernel') diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 72a3f5998dd2..939e535a3442 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -11356,6 +11356,11 @@ static bool is_kfunc_destructive(struct bpf_call_arg_meta *meta) return meta->kfunc_flags & KF_DESTRUCTIVE; } +static bool is_kfunc_perfmon(struct bpf_call_arg_meta *meta) +{ + return meta->kfunc_flags & KF_PERFMON; +} + static bool is_kfunc_rcu(struct bpf_call_arg_meta *meta) { return meta->kfunc_flags & KF_RCU; @@ -13834,6 +13839,15 @@ static int check_kfunc_call(struct bpf_verifier_env *env, struct bpf_insn *insn, return -EACCES; } + if (is_kfunc_perfmon(&meta) && !env->allow_ptr_leaks) { + verbose(env, "%s is allowed only to CAP_PERFMON and CAP_SYS_ADMIN\n", + func_name); + operation = bpf_diag_fmt(env, "kfunc %s", func_name); + bpf_diag_policy(env, insn_idx, operation, "the kfunc requires CAP_PERFMON", + "Load the program with CAP_PERFMON, or avoid the kfunc."); + return -EPERM; + } + sleepable = bpf_is_kfunc_sleepable(&meta); if (sleepable && !in_sleepable(env)) { verbose(env, "program must be sleepable to call sleepable kfunc %s\n", func_name); -- cgit v1.2.3 From 81c975aae375d2053fa2926ee3730f02e713140c Mon Sep 17 00:00:00 2001 From: Daniel Borkmann Date: Thu, 10 Sep 2026 23:35:08 +0200 Subject: bpf: Require CAP_PERFMON for kfuncs reading memory Mark fault-safe probe reading kfuncs as KF_PERFMON, similarly as we do for the old-style BPF helper equivalents. bpf_rdonly_cast() is included in this list as well as it returns PTR_TO_MEM | MEM_RDONLY | PTR_UNTRUSTED for an unchecked object and is using fault-safe BPF_PROBE_MEM. Note that only the void form of bpf_rdonly_cast() produced a register that was readable without CAP_PERFMON. For a struct type id the kfunc returns PTR_TO_BTF_ID | PTR_UNTRUSTED, whose dereference has always been gated in check_ptr_to_btf_access(). The flag is not conditional on the type id, so for the latter it only moves the rejection from the dereference to the call itself, which is the better place to report it anyway. The bpf_stream_vprintk() and bpf_stream_print_stack() kfuncs are marked as well. The former ends up in the same bpf_bprintf_prepare() as the bpf_snprintf() helper, where %pks, %pus and %pI4 read through a program- supplied address and %pB resolves one into a symbol. The latter walks the stack and prints each instruction pointer via %pS. Lastly, bpf_get_kmem_cache() takes a raw scalar address that the verifier does not constrain and dereferences the page/slab metadata for it. Field reads on the returned pointer are still blocked (PTR_TO_BTF_ID | PTR_UNTRUSTED -> check_ptr_to_btf_access() results in -EPERM without the CAP), but the NULL/non-NULL result is observable. Reported-by: STAR Labs SG Signed-off-by: Daniel Borkmann Link: https://lore.kernel.org/r/20260910213510.49358-2-daniel@iogearbox.net Signed-off-by: Alexei Starovoitov --- kernel/bpf/helpers.c | 60 ++++++++++++++++++++++++++-------------------------- 1 file changed, 30 insertions(+), 30 deletions(-) (limited to 'kernel') diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c index b3cc5c8fc875..712dca5a2c5b 100644 --- a/kernel/bpf/helpers.c +++ b/kernel/bpf/helpers.c @@ -4883,7 +4883,7 @@ BTF_ID(func, bpf_cgroup_release_dtor) BTF_KFUNCS_START(common_btf_ids) BTF_ID_FLAGS(func, bpf_cast_to_kern_ctx, KF_FASTCALL) -BTF_ID_FLAGS(func, bpf_rdonly_cast, KF_FASTCALL) +BTF_ID_FLAGS(func, bpf_rdonly_cast, KF_FASTCALL | KF_PERFMON) BTF_ID_FLAGS(func, bpf_rcu_read_lock) BTF_ID_FLAGS(func, bpf_rcu_read_unlock) BTF_ID_FLAGS(func, bpf_dynptr_slice, KF_RET_NULL) @@ -4920,26 +4920,26 @@ BTF_ID_FLAGS(func, bpf_wq_set_callback, KF_IMPLICIT_ARGS) BTF_ID_FLAGS(func, bpf_wq_start) BTF_ID_FLAGS(func, bpf_preempt_disable) BTF_ID_FLAGS(func, bpf_preempt_enable) -BTF_ID_FLAGS(func, bpf_iter_bits_new, KF_ITER_NEW) +BTF_ID_FLAGS(func, bpf_iter_bits_new, KF_ITER_NEW | KF_PERFMON) BTF_ID_FLAGS(func, bpf_iter_bits_next, KF_ITER_NEXT | KF_RET_NULL) BTF_ID_FLAGS(func, bpf_iter_bits_destroy, KF_ITER_DESTROY) -BTF_ID_FLAGS(func, bpf_copy_from_user_str, KF_SLEEPABLE) -BTF_ID_FLAGS(func, bpf_copy_from_user_task_str, KF_SLEEPABLE) -BTF_ID_FLAGS(func, bpf_get_kmem_cache) +BTF_ID_FLAGS(func, bpf_copy_from_user_str, KF_SLEEPABLE | KF_PERFMON) +BTF_ID_FLAGS(func, bpf_copy_from_user_task_str, KF_SLEEPABLE | KF_PERFMON) +BTF_ID_FLAGS(func, bpf_get_kmem_cache, KF_PERFMON) BTF_ID_FLAGS(func, bpf_iter_kmem_cache_new, KF_ITER_NEW | KF_SLEEPABLE) BTF_ID_FLAGS(func, bpf_iter_kmem_cache_next, KF_ITER_NEXT | KF_RET_NULL | KF_SLEEPABLE) BTF_ID_FLAGS(func, bpf_iter_kmem_cache_destroy, KF_ITER_DESTROY | KF_SLEEPABLE) BTF_ID_FLAGS(func, bpf_local_irq_save) BTF_ID_FLAGS(func, bpf_local_irq_restore) #ifdef CONFIG_BPF_EVENTS -BTF_ID_FLAGS(func, bpf_probe_read_user_dynptr) -BTF_ID_FLAGS(func, bpf_probe_read_kernel_dynptr) -BTF_ID_FLAGS(func, bpf_probe_read_user_str_dynptr) -BTF_ID_FLAGS(func, bpf_probe_read_kernel_str_dynptr) -BTF_ID_FLAGS(func, bpf_copy_from_user_dynptr, KF_SLEEPABLE) -BTF_ID_FLAGS(func, bpf_copy_from_user_str_dynptr, KF_SLEEPABLE) -BTF_ID_FLAGS(func, bpf_copy_from_user_task_dynptr, KF_SLEEPABLE) -BTF_ID_FLAGS(func, bpf_copy_from_user_task_str_dynptr, KF_SLEEPABLE) +BTF_ID_FLAGS(func, bpf_probe_read_user_dynptr, KF_PERFMON) +BTF_ID_FLAGS(func, bpf_probe_read_kernel_dynptr, KF_PERFMON) +BTF_ID_FLAGS(func, bpf_probe_read_user_str_dynptr, KF_PERFMON) +BTF_ID_FLAGS(func, bpf_probe_read_kernel_str_dynptr, KF_PERFMON) +BTF_ID_FLAGS(func, bpf_copy_from_user_dynptr, KF_SLEEPABLE | KF_PERFMON) +BTF_ID_FLAGS(func, bpf_copy_from_user_str_dynptr, KF_SLEEPABLE | KF_PERFMON) +BTF_ID_FLAGS(func, bpf_copy_from_user_task_dynptr, KF_SLEEPABLE | KF_PERFMON) +BTF_ID_FLAGS(func, bpf_copy_from_user_task_str_dynptr, KF_SLEEPABLE | KF_PERFMON) #endif #ifdef CONFIG_DMA_SHARED_BUFFER BTF_ID_FLAGS(func, bpf_iter_dmabuf_new, KF_ITER_NEW | KF_SLEEPABLE) @@ -4947,26 +4947,26 @@ BTF_ID_FLAGS(func, bpf_iter_dmabuf_next, KF_ITER_NEXT | KF_RET_NULL | KF_SLEEPAB BTF_ID_FLAGS(func, bpf_iter_dmabuf_destroy, KF_ITER_DESTROY | KF_SLEEPABLE) #endif BTF_ID_FLAGS(func, __bpf_trap) -BTF_ID_FLAGS(func, bpf_strcmp); -BTF_ID_FLAGS(func, bpf_strcasecmp); -BTF_ID_FLAGS(func, bpf_strncasecmp); -BTF_ID_FLAGS(func, bpf_strchr); -BTF_ID_FLAGS(func, bpf_strchrnul); -BTF_ID_FLAGS(func, bpf_strnchr); -BTF_ID_FLAGS(func, bpf_strrchr); -BTF_ID_FLAGS(func, bpf_strlen); -BTF_ID_FLAGS(func, bpf_strnlen); -BTF_ID_FLAGS(func, bpf_strspn); -BTF_ID_FLAGS(func, bpf_strcspn); -BTF_ID_FLAGS(func, bpf_strstr); -BTF_ID_FLAGS(func, bpf_strcasestr); -BTF_ID_FLAGS(func, bpf_strnstr); -BTF_ID_FLAGS(func, bpf_strncasestr); +BTF_ID_FLAGS(func, bpf_strcmp, KF_PERFMON); +BTF_ID_FLAGS(func, bpf_strcasecmp, KF_PERFMON); +BTF_ID_FLAGS(func, bpf_strncasecmp, KF_PERFMON); +BTF_ID_FLAGS(func, bpf_strchr, KF_PERFMON); +BTF_ID_FLAGS(func, bpf_strchrnul, KF_PERFMON); +BTF_ID_FLAGS(func, bpf_strnchr, KF_PERFMON); +BTF_ID_FLAGS(func, bpf_strrchr, KF_PERFMON); +BTF_ID_FLAGS(func, bpf_strlen, KF_PERFMON); +BTF_ID_FLAGS(func, bpf_strnlen, KF_PERFMON); +BTF_ID_FLAGS(func, bpf_strspn, KF_PERFMON); +BTF_ID_FLAGS(func, bpf_strcspn, KF_PERFMON); +BTF_ID_FLAGS(func, bpf_strstr, KF_PERFMON); +BTF_ID_FLAGS(func, bpf_strcasestr, KF_PERFMON); +BTF_ID_FLAGS(func, bpf_strnstr, KF_PERFMON); +BTF_ID_FLAGS(func, bpf_strncasestr, KF_PERFMON); #if defined(CONFIG_BPF_LSM) && defined(CONFIG_CGROUPS) BTF_ID_FLAGS(func, bpf_cgroup_read_xattr, KF_RCU) #endif -BTF_ID_FLAGS(func, bpf_stream_vprintk, KF_IMPLICIT_ARGS | KF_SPINLOCK_SAFE) -BTF_ID_FLAGS(func, bpf_stream_print_stack, KF_IMPLICIT_ARGS | KF_SPINLOCK_SAFE) +BTF_ID_FLAGS(func, bpf_stream_vprintk, KF_IMPLICIT_ARGS | KF_SPINLOCK_SAFE | KF_PERFMON) +BTF_ID_FLAGS(func, bpf_stream_print_stack, KF_IMPLICIT_ARGS | KF_SPINLOCK_SAFE | KF_PERFMON) BTF_ID_FLAGS(func, bpf_task_work_schedule_signal, KF_IMPLICIT_ARGS) BTF_ID_FLAGS(func, bpf_task_work_schedule_resume, KF_IMPLICIT_ARGS) BTF_ID_FLAGS(func, bpf_dynptr_from_file) -- cgit v1.2.3 From f9191460cd805e84eace0884c75c67ec719fa1d8 Mon Sep 17 00:00:00 2001 From: Daniel Borkmann Date: Thu, 10 Sep 2026 23:35:09 +0200 Subject: bpf: Require CAP_PERFMON for untrusted read-only memory reads Marking bpf_rdonly_cast() KF_PERFMON CAP-limits one producer of PTR_TO_MEM | MEM_RDONLY | PTR_UNTRUSTED, but not the type itself. A global subprogram argument tagged __arg_untrusted results in the same register with no kfunc call. Reported-by: STAR Labs SG Signed-off-by: Daniel Borkmann Link: https://lore.kernel.org/r/20260910213510.49358-3-daniel@iogearbox.net Signed-off-by: Alexei Starovoitov --- kernel/bpf/verifier.c | 9 +++++++++ 1 file changed, 9 insertions(+) (limited to 'kernel') diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 939e535a3442..8058f684a9ea 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -6453,6 +6453,15 @@ static int check_mem_access(struct bpf_verifier_env *env, int insn_idx, struct b return -EACCES; } + if (rdonly_untrusted && !env->allow_ptr_leaks) { + verbose(env, "%s access is allowed only to CAP_PERFMON and CAP_SYS_ADMIN\n", + reg_type_str(env, reg->type)); + bpf_diag_policy(env, insn_idx, "read from untrusted read-only memory", + "the access requires CAP_PERFMON", + "Load the program with CAP_PERFMON, or avoid dereferencing untrusted pointers."); + return -EPERM; + } + /* * Accesses to untrusted PTR_TO_MEM are done through probe * instructions, hence no need to check bounds in that case. -- cgit v1.2.3 From 2936aed9b02162df7fbe08fcd6bfbb3270ad9f95 Mon Sep 17 00:00:00 2001 From: Daniel Borkmann Date: Thu, 10 Sep 2026 20:56:04 +0200 Subject: bpf: Clear scalar delta on narrowing stack spill check_stack_write_fixed_off() breaks the scalar link on a narrowing spill by zeroing the id of the destination stack slot, but leaves the delta in place. save_register_state() has just copied the source register verbatim, so the slot keeps the BPF_ADD_CONST delta of a register it is no longer linked to. This is the same shape as the case addressed in 1b327732c846 ("bpf: Clear delta when clearing reg id for non-{add,sub} ops"). Unlike the latter, no miscomputation seems reachable, so mainly consistency. Signed-off-by: Daniel Borkmann Acked-by: Eduard Zingerman Link: https://lore.kernel.org/r/20260910185604.44949-1-daniel@iogearbox.net Signed-off-by: Alexei Starovoitov --- kernel/bpf/verifier.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'kernel') diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 8058f684a9ea..1b0b1fb62878 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -3582,7 +3582,7 @@ static int check_stack_write_fixed_off(struct bpf_verifier_env *env, save_register_state(env, state, spi, reg, size); /* Break the relation on a narrowing spill. */ if (!reg_value_fits) - state->stack[spi].spilled_ptr.id = 0; + clear_scalar_id(&state->stack[spi].spilled_ptr); } else if (!reg && !(off % BPF_REG_SIZE) && is_bpf_st_mem(insn) && env->bpf_capable) { struct bpf_reg_state *tmp_reg = &env->fake_reg[0]; -- cgit v1.2.3 From b0b3dc66529676228cb938cbcad66920f735c223 Mon Sep 17 00:00:00 2001 From: Jiayuan Chen Date: Thu, 10 Sep 2026 20:22:55 +0800 Subject: bpf: Fix divide-by-zero in btf_struct_walk() When an access goes past the struct and the last member is a flexible array, btf_struct_walk() folds the offset back into a single element with (off - moff) % t->size, but never checks that the element type has a size. BTF takes an empty struct, so this in program BTF /* event could be empty */ struct event { #ifdef HAVE_TIMESTAMP __u64 ts; #endif }; struct batch { int nr; struct event events[]; }; divides by zero at prog load time. Getting there needs a PTR_TO_BTF_ID that is not MEM_ALLOC, e.g. a plain read of a local kptr stashed in a map from a sleepable program. Oops: divide error: 0000 [#1] SMP KASAN PTI RIP: 0010:btf_struct_walk+0x53f/0x1570 Call Trace: btf_struct_access+0x42a/0xcd0 check_ptr_to_btf_access+0x4dc/0x1160 check_mem_access+0x3a45/0x8740 check_load_mem+0x36a/0xd10 do_check_common+0x3ef0/0xb210 bpf_check+0x6d3b/0x8580 bpf_prog_load+0xf7c/0x2720 __sys_bpf+0xa83/0x3690 __x64_sys_bpf+0xc7/0x150 x64_sys_call+0x1f3f/0x27e0 do_syscall_64+0xe5/0x610 entry_SYSCALL_64_after_hwframe+0x76/0x7e Reject a zero-sized element type. The fixed array path in the same function already bails out on the same thing: btf_struct_walk() ... /* skip empty array */ if (moff == mtrue_end) continue; msize /= total_nelems; Fixes: 9c5f8a1008a1 ("bpf: Support variable length array in tracing programs") Signed-off-by: Jiayuan Chen Acked-by: Eduard Zingerman Link: https://lore.kernel.org/r/20260910122316.186384-1-jiayuan.chen@linux.dev Signed-off-by: Alexei Starovoitov --- kernel/bpf/btf.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'kernel') diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c index 9f33e95d5741..d67a169ba2bb 100644 --- a/kernel/bpf/btf.c +++ b/kernel/bpf/btf.c @@ -7187,7 +7187,7 @@ again: if (btf_type_is_int(t)) return WALK_SCALAR; - if (!btf_type_is_struct(t)) + if (!btf_type_is_struct(t) || !t->size) goto error; off = (off - moff) % t->size; -- cgit v1.2.3 From 0d7823cd4cda35f2060a685fa276ff7709915abc Mon Sep 17 00:00:00 2001 From: Siddharth Chintamaneni Date: Wed, 2 Sep 2026 17:14:13 +0000 Subject: bpf: Allow terminal gotox instructions check_subprogs() treats gotox as a direct jump and validates its reserved zero offset. When gotox is the final instruction, this produces a synthetic successor one instruction past the end of the subprogram and rejects an otherwise valid program. Skip direct-offset validation for gotox and accept it as a non-fallthrough terminal instruction. Its actual targets remain validated from the instruction-array jump table during CFG construction. Fixes: 493d9e0d6083 ("bpf, x86: add support for indirect jumps") Signed-off-by: Siddharth Chintamaneni Reviewed-by: Anton Protopopov Link: https://lore.kernel.org/r/20260902171414.96165-1-sidchintamaneni@gmail.com Signed-off-by: Alexei Starovoitov --- kernel/bpf/verifier.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) (limited to 'kernel') diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 1b0b1fb62878..ddba53eaa333 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -3042,6 +3042,8 @@ static int check_subprogs(struct bpf_verifier_env *env) subprog[cur_subprog].exit_idx = i; goto next; } + if (insn_is_gotox(&insn[i])) + goto next; off = i + bpf_jmp_offset(&insn[i]) + 1; if (off < subprog_start || off >= subprog_end) { verbose(env, "jump out of range from insn %d to %d\n", i, off); @@ -3061,7 +3063,8 @@ next: */ if (code != (BPF_JMP | BPF_EXIT) && code != (BPF_JMP32 | BPF_JA) && - code != (BPF_JMP | BPF_JA)) { + code != (BPF_JMP | BPF_JA) && + !insn_is_gotox(&insn[i])) { verbose(env, "last insn is not an exit or jmp\n"); bpf_diag_program_structure( env, i, "subprogram can fall through", -- cgit v1.2.3 From 85136bf22404474a815fc0ed26ec0d1cbc1bc3f9 Mon Sep 17 00:00:00 2001 From: "Jose Fernandez (Anthropic)" Date: Wed, 9 Sep 2026 17:51:04 +0000 Subject: bpf: Avoid soft lockup in __htab_map_lookup_and_delete_batch() __htab_map_lookup_and_delete_batch() has no rescheduling point. The batch count bounds how many entries are copied out, not how many buckets are visited, so one BPF_MAP_LOOKUP_BATCH call can walk the map end to end. The empty-bucket fast path is worse: it stays inside a single rcu_read_lock() / bpf_disable_instrumentation() section for any run of consecutive empty buckets. That holds up on small maps, but it falls apart at scale. On a 144-CPU arm64 host running a CONFIG_PREEMPT_NONE kernel, periodic BPF_MAP_LOOKUP_BATCH calls against an LRU hash map with 16,777,216 buckets held a CPU inside the batch op for 77+ seconds and triggered the soft lockup watchdog. Commit 75134f16e7dd ("bpf: Add schedule points in batch ops") fixed this same problem in the generic batch ops, but not in this htab-native path, which every htab-based hash map variant uses for its lookup[_and_delete] batch ops. Complete that fix here. Leave the critical section after 64 consecutive empty buckets, call cond_resched_tasks_rcu_qs(), and resume at the saved bucket cursor. No locks are held at that point, and resuming from the cursor is already the function's behavior for non-empty buckets. Add the same call to the per-bucket loop after copy_to_user(), where every lock has been dropped. cond_resched_rcu() is not enough here: sleeping with bpf_prog_active elevated makes tracing programs on that CPU silently skip their invocations. Plain cond_resched() is not enough either. It is a no-op under PREEMPT and PREEMPT_LAZY, the only models arm64 and x86 have offered since commit 7dadeaa6e851 ("sched: Further restrict the preemption modes"). It is also never a Tasks RCU quiescent state, in any model: the reschedule counts as a preemption. The walking task stays a holdout and stalls every synchronize_rcu_tasks() caller, ftrace and BPF trampoline teardown included, until the syscall returns [1]. cond_resched_tasks_rcu_qs() is the usual tool for that [2]. It reports the quiescent state at each yield and still reschedules as cond_resched() does on PREEMPT_NONE and PREEMPT_VOLUNTARY kernels. Fixes: 057996380a42 ("bpf: Add batch ops to all htab bpf map") Cc: "Paul E. McKenney" Cc: Rik van Riel Link: https://lore.kernel.org/bpf/20260715215314.44423f47@fangorn/ [1] Link: https://lore.kernel.org/bpf/9d444098-7c03-4163-af12-bd0a79a51443@paulmck-laptop/ [2] Assisted-by: LLM Signed-off-by: Jose Fernandez (Anthropic) Signed-off-by: Josef Bacik Reviewed-by: Rik van Riel Link: https://lore.kernel.org/r/20260909-b4-htab-batch-resched-v2-1-0cb529d8f95a@toxicpanda.com Signed-off-by: Alexei Starovoitov --- kernel/bpf/hashtab.c | 24 +++++++++++++++++++++--- 1 file changed, 21 insertions(+), 3 deletions(-) (limited to 'kernel') diff --git a/kernel/bpf/hashtab.c b/kernel/bpf/hashtab.c index 6f331c80130d..a72dc5b9f184 100644 --- a/kernel/bpf/hashtab.c +++ b/kernel/bpf/hashtab.c @@ -1772,6 +1772,12 @@ static int htab_lru_percpu_map_lookup_and_delete_elem(struct bpf_map *map, flags); } +/* + * Max consecutive empty buckets to walk in one RCU + + * instrumentation-disabled section before rescheduling. + */ +#define HTAB_BATCH_EMPTY_RESCHED 64 + static int __htab_map_lookup_and_delete_batch(struct bpf_map *map, const union bpf_attr *attr, @@ -1793,6 +1799,7 @@ __htab_map_lookup_and_delete_batch(struct bpf_map *map, unsigned long flags = 0; bool locked = false; struct htab_elem *l; + u32 empty_cnt = 0; struct bucket *b; int ret = 0; @@ -1971,12 +1978,21 @@ again_nocopy: } next_batch: - /* If we are not copying data, we can go to next bucket and avoid - * unlocking the rcu. + /* + * If we are not copying data, we can go to next bucket and avoid + * unlocking the rcu. Bound the walk though: after + * HTAB_BATCH_EMPTY_RESCHED consecutive empty buckets, fully exit + * the critical section (no locks are held here) and reschedule. */ if (!bucket_cnt && (batch + 1 < htab->n_buckets)) { batch++; - goto again_nocopy; + if (++empty_cnt < HTAB_BATCH_EMPTY_RESCHED) + goto again_nocopy; + empty_cnt = 0; + rcu_read_unlock(); + bpf_enable_instrumentation(); + cond_resched_tasks_rcu_qs(); + goto again; } rcu_read_unlock(); @@ -1990,11 +2006,13 @@ next_batch: } total += bucket_cnt; + empty_cnt = 0; batch++; if (batch >= htab->n_buckets) { ret = -ENOENT; goto after_loop; } + cond_resched_tasks_rcu_qs(); goto again; after_loop: -- cgit v1.2.3 From c7a1c6e8004ab12a9c9bfdcb603f60f9bf4a3cee Mon Sep 17 00:00:00 2001 From: fangqiurong Date: Sat, 12 Sep 2026 21:15:18 +0800 Subject: sched_ext: Close the pre-enable ops error claim window scx_alloc_and_add_sched() publishes ops->priv before scx_root_enable_workfn() switches the state to SCX_ENABLING. An error claimed via scx_bpf_error_bstr() from an associated BPF program in that window is consumed by scx_disable_workfn(), which takes the pre-enable shortcut in scx_root_disable(). The shortcut returns without any teardown and restores SCX_DISABLED with an unconditional scx_set_enable_state() xchg racing the enable workfn's own transition. The enable then completes with the claim consumed: the scheduler stays up but can never be disabled again, and bpf_scx_unreg() frees it while still in use, resulting in a use-after-free. Both WARN_ON_ONCE()s fire back to back: WARNING: kernel/sched/ext/ext.c:7522 at scx_root_enable_workfn+0xeec/0x1be0, CPU#3: scx_enable_help/276 WARNING: kernel/sched/ext/ext.c:6398 at scx_root_disable+0xb50/0xdb8, CPU#0: sched_ext_helpe/664 scx_root_enable_workfn() switches to SCX_ENABLING before the scheduler allocation, so ops->priv is never visible while SCX_DISABLED. The allocation failure path restores SCX_DISABLED. Fixes: 105dcd005be2 ("sched_ext: Introduce scx_prog_sched()") Cc: stable@vger.kernel.org Signed-off-by: fangqiurong Signed-off-by: Tejun Heo --- kernel/sched/ext/ext.c | 16 +++++++++------- 1 file changed, 9 insertions(+), 7 deletions(-) (limited to 'kernel') diff --git a/kernel/sched/ext/ext.c b/kernel/sched/ext/ext.c index adf5993fa597..83999203a63a 100644 --- a/kernel/sched/ext/ext.c +++ b/kernel/sched/ext/ext.c @@ -7516,22 +7516,24 @@ static void scx_root_enable_workfn(struct kthread_work *work) #ifdef CONFIG_EXT_SUB_SCHED cgroup_get(cgrp); #endif + /* + * Transition to ENABLING to arm the disable path. Allocation failure + * still unwinds locally. Full disabling on failure applies only after + * scx_alloc_and_add_sched() succeeds. + */ + WARN_ON_ONCE(scx_set_enable_state(SCX_ENABLING) != SCX_DISABLED); + WARN_ON_ONCE(scx_root); + sch = scx_alloc_and_add_sched(cmd, cgrp, NULL); if (IS_ERR(sch)) { ret = PTR_ERR(sch); + WARN_ON_ONCE(scx_set_enable_state(SCX_DISABLED) != SCX_ENABLING); goto err_free_tid_hash; } if (sch->is_cid_type) static_branch_enable(&__scx_is_cid_type); - /* - * Transition to ENABLING and clear exit info to arm the disable path. - * Failure triggers full disabling from here on. - */ - WARN_ON_ONCE(scx_set_enable_state(SCX_ENABLING) != SCX_DISABLED); - WARN_ON_ONCE(scx_root); - atomic_long_set(&scx_nr_rejected, 0); for_each_possible_cpu(cpu) { -- cgit v1.2.3 From 1c21452d02eec2f008e2c5535820f85adbd7587a Mon Sep 17 00:00:00 2001 From: Pu Lehui Date: Sat, 5 Sep 2026 02:11:39 +0000 Subject: bpf: Fix UAF due to concurrent consumption of ttrace lists in alloc_bulk Syzkaller repeatedly triggered UAF splats related to nodes in waiting_for_gp_ttrace within the bpf memalloc: BUG: KASAN: slab-use-after-free in llist_del_first+0x85/0x110 lib/llist.c:61 Read of size 8 at addr ffff8881572cd080 by task syz.4.470/5112 ... llist_del_first+0x85/0x110 lib/llist.c:61 alloc_bulk+0x193/0x460 kernel/bpf/memalloc.c:229 bpf_mem_refill+0x386/0x560 kernel/bpf/memalloc.c:436 Freed by task 14: ... __free_rcu kernel/bpf/memalloc.c:281 [inline] __free_rcu_tasks_trace+0x48/0xd0 kernel/bpf/memalloc.c:291 rcu_tasks_invoke_cbs+0x1ec/0x3e0 kernel/rcu/tasks.h:571 rcu_tasks_one_gp+0x13d/0x220 kernel/rcu/tasks.h:621 rcu_tasks_kthread+0xf3/0x120 kernel/rcu/tasks.h:651 The reason is that the UAF occurs after the RCU Tasks Trace GP expires: when the __free_rcu() callback runs, there is no synchronization protecting llist_del_all() against concurrent alloc_bulk() operating on waiting_for_gp_ttrace, leading to the race condition below: CPU0 CPU1 __free_rcu (RCU Tasks Trace callback) alloc_bulk llist_del_first(&c->waiting_for_gp_ttrace) entry = smp_load_acquire(&head->first); do { if (entry == NULL) return NULL; free_all(llist_del_all(&c->waiting_for_gp_ttrace)) llist_for_each_safe(pos, t, llnode) free_one(pos); next = READ_ONCE(entry->next); <-- trigger UAF } while (!try_cmpxchg(&head->first, &entry, next)); In addition, there is also a theoretical race condition on the free_by_rcu_ttrace list. This race requires two preconditions: an in-flight Tasks Trace GP keeping c->call_rcu_ttrace_in_progress == 1, and concurrent cross-CPU frees repopulating c->free_by_rcu_ttrace with new nodes. Under these conditions, the following scenario triggers UAF: // CPU0 // irq work is still busy (on PREEMPT_RT) alloc_bulk() llist_del_first(&c->free_by_rcu_ttrace) entry = smp_load_acquire(&head->first); do { if (entry == NULL) return NULL; // CPU1 bpf_mem_alloc_destroy() WRITE_ONCE(c->draining, true) // wait for CPU0 irq_work_sync() // CPU2 do_call_rcu_ttrace(tgt(CPU0)) if (c->draining) { llist_del_all(&c->free_by_rcu_ttrace) free_all() } // CPU0 continue next = READ_ONCE(entry->next); <-- trigger UAF while (!try_cmpxchg(&head->first, &entry, next)); Fix this by introducing a raw spinlock to synchronize the concurrent consumption on waiting_for_gp_ttrace and free_by_rcu_ttrace. Fixes: 04fabf00b4d3 ("bpf: Allow reuse from waiting_for_gp_ttrace list.") Suggested-by: Alexei Starovoitov Suggested-by: Hou Tao Signed-off-by: Pu Lehui Acked-by: Hou Tao Link: https://lore.kernel.org/r/20260905021139.4116529-1-pulehui@huaweicloud.com Signed-off-by: Alexei Starovoitov --- kernel/bpf/memalloc.c | 50 ++++++++++++++++++++++++++++---------------------- 1 file changed, 28 insertions(+), 22 deletions(-) (limited to 'kernel') diff --git a/kernel/bpf/memalloc.c b/kernel/bpf/memalloc.c index e9662db7198f..8a8f088e83e6 100644 --- a/kernel/bpf/memalloc.c +++ b/kernel/bpf/memalloc.c @@ -119,6 +119,7 @@ struct bpf_mem_cache { struct llist_head waiting_for_gp_ttrace; struct rcu_head rcu_ttrace; atomic_t call_rcu_ttrace_in_progress; + raw_spinlock_t lock; }; struct bpf_mem_caches { @@ -214,25 +215,24 @@ static void alloc_bulk(struct bpf_mem_cache *c, int cnt, int node, bool atomic) gfp = __GFP_NOWARN | __GFP_ACCOUNT; gfp |= atomic ? GFP_NOWAIT : GFP_KERNEL; - for (i = 0; i < cnt; i++) { - /* - * For every 'c' llist_del_first(&c->free_by_rcu_ttrace); is - * done only by one CPU == current CPU. Other CPUs might - * llist_add() and llist_del_all() in parallel. - */ - obj = llist_del_first(&c->free_by_rcu_ttrace); - if (!obj) - break; - add_obj_to_free_list(c, obj); - } - if (i >= cnt) - return; + /* + * c->lock serializes concurrent llist_del_first() against + * llist_del_all() in __free_rcu() and do_call_rcu_ttrace(). + */ + scoped_guard(raw_spinlock_irqsave, &c->lock) { + for (i = 0; i < cnt; i++) { + obj = llist_del_first(&c->free_by_rcu_ttrace); + if (!obj) + break; + add_obj_to_free_list(c, obj); + } - for (; i < cnt; i++) { - obj = llist_del_first(&c->waiting_for_gp_ttrace); - if (!obj) - break; - add_obj_to_free_list(c, obj); + for (; i < cnt; i++) { + obj = llist_del_first(&c->waiting_for_gp_ttrace); + if (!obj) + break; + add_obj_to_free_list(c, obj); + } } if (i >= cnt) return; @@ -279,8 +279,12 @@ static int free_all(struct bpf_mem_cache *c, struct llist_node *llnode, bool per static void __free_rcu(struct rcu_head *head) { struct bpf_mem_cache *c = container_of(head, struct bpf_mem_cache, rcu_ttrace); + struct llist_node *llnode; + + scoped_guard(raw_spinlock_irqsave, &c->lock) + llnode = llist_del_all(&c->waiting_for_gp_ttrace); - free_all(c, llist_del_all(&c->waiting_for_gp_ttrace), !!c->percpu_size); + free_all(c, llnode, !!c->percpu_size); atomic_set(&c->call_rcu_ttrace_in_progress, 0); } @@ -300,7 +304,8 @@ static void do_call_rcu_ttrace(struct bpf_mem_cache *c) if (atomic_xchg(&c->call_rcu_ttrace_in_progress, 1)) { if (unlikely(READ_ONCE(c->draining))) { - llnode = llist_del_all(&c->free_by_rcu_ttrace); + scoped_guard(raw_spinlock_irqsave, &c->lock) + llnode = llist_del_all(&c->free_by_rcu_ttrace); free_all(c, llnode, !!c->percpu_size); } return; @@ -535,6 +540,7 @@ int bpf_mem_alloc_init(struct bpf_mem_alloc *ma, int size, bool percpu) c->objcg = objcg; c->percpu_size = percpu_size; c->tgt = c; + raw_spin_lock_init(&c->lock); init_refill_work(c); prefill_mem_cache(c, cpu); } @@ -557,7 +563,7 @@ int bpf_mem_alloc_init(struct bpf_mem_alloc *ma, int size, bool percpu) c->objcg = objcg; c->percpu_size = percpu_size; c->tgt = c; - + raw_spin_lock_init(&c->lock); init_refill_work(c); prefill_mem_cache(c, cpu); } @@ -609,7 +615,7 @@ int bpf_mem_alloc_percpu_unit_init(struct bpf_mem_alloc *ma, int size) c->objcg = objcg; c->percpu_size = percpu_size; c->tgt = c; - + raw_spin_lock_init(&c->lock); init_refill_work(c); prefill_mem_cache(c, cpu); } -- cgit v1.2.3 From 953824e508b27d12837e32ef37ef6248e1f6fc7a Mon Sep 17 00:00:00 2001 From: Masoud Aghasi Date: Thu, 3 Sep 2026 09:27:34 +0100 Subject: bpf: Fix u32 overflow issue in map batch operations Several map batch operation implementations such as generic_map_lookup_batch() use calculations in the form of "values + cp * map->value_size" to compute the desired userspace memory address for reading or writing. This can overflow the u32 type (the result of "cp * map->value_size") when the map size exceeds 4GB. generic_map_lookup_batch() may corrupt values for some keys in userspace memory, and in some cases it mismatches values for some keys while still reporting success. Other batch operations may fail to delete or update some keys, or the syscall may return unexpected errors. Add size_t casts to prevent the affected offset and size calculations from overflowing. Fixes: cb4d03ab499d ("bpf: Add generic support for lookup batch op") Fixes: aa2e93b8e58e ("bpf: Add generic support for update and delete batch ops") Fixes: 057996380a42 ("bpf: Add batch ops to all htab bpf map") Signed-off-by: Masoud Aghasi Link: https://lore.kernel.org/r/20260903082734.623904-1-maghasi@disroot.org Signed-off-by: Alexei Starovoitov --- kernel/bpf/hashtab.c | 8 ++++---- kernel/bpf/syscall.c | 10 +++++----- 2 files changed, 9 insertions(+), 9 deletions(-) (limited to 'kernel') diff --git a/kernel/bpf/hashtab.c b/kernel/bpf/hashtab.c index a72dc5b9f184..4f495dcbf670 100644 --- a/kernel/bpf/hashtab.c +++ b/kernel/bpf/hashtab.c @@ -1997,10 +1997,10 @@ next_batch: rcu_read_unlock(); bpf_enable_instrumentation(); - if (bucket_cnt && (copy_to_user(ukeys + total * key_size, keys, - key_size * bucket_cnt) || - copy_to_user(uvalues + total * value_size, values, - value_size * bucket_cnt))) { + if (bucket_cnt && (copy_to_user(ukeys + (size_t)total * key_size, keys, + (size_t)key_size * bucket_cnt) || + copy_to_user(uvalues + (size_t)total * value_size, values, + (size_t)value_size * bucket_cnt))) { ret = -EFAULT; goto after_loop; } diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index c7bc9ba9b331..853b47f81384 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -2036,7 +2036,7 @@ int generic_map_delete_batch(struct bpf_map *map, for (cp = 0; cp < max_count; cp++) { err = -EFAULT; - if (copy_from_user(key, keys + cp * map->key_size, + if (copy_from_user(key, keys + (size_t)cp * map->key_size, map->key_size)) break; @@ -2098,9 +2098,9 @@ int generic_map_update_batch(struct bpf_map *map, struct file *map_file, for (cp = 0; cp < max_count; cp++) { err = -EFAULT; - if (copy_from_user(key, keys + cp * map->key_size, + if (copy_from_user(key, keys + (size_t)cp * map->key_size, map->key_size) || - copy_from_user(value, values + cp * value_size, value_size)) + copy_from_user(value, values + (size_t)cp * value_size, value_size)) break; err = bpf_map_update_value(map, map_file, key, value, @@ -2179,12 +2179,12 @@ int generic_map_lookup_batch(struct bpf_map *map, if (err) goto free_buf; - if (copy_to_user(keys + cp * map->key_size, key, + if (copy_to_user(keys + (size_t)cp * map->key_size, key, map->key_size)) { err = -EFAULT; goto free_buf; } - if (copy_to_user(values + cp * value_size, value, value_size)) { + if (copy_to_user(values + (size_t)cp * value_size, value, value_size)) { err = -EFAULT; goto free_buf; } -- cgit v1.2.3 From 057dac23d329d5c5ed62352f2659a39fd46c6d4a Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Michal=20Koutn=C3=BD?= Date: Mon, 14 Sep 2026 14:19:10 +0200 Subject: cgroup: Avoid iteration of dying tasks with zero refcount MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The commit 260fbcb92bbea ("cgroup: Move dying_tasks cleanup from cgroup_task_release() to cgroup_task_free()") extended the lifetime of tasks on the dying_tasks list. The iterators have provision to go through dying_tasks because of dying threadgroup leaders or explicit CSS_TASK_ITER_WITH_DEAD, however, it was expected that such tasks can obtain a new reference (that is possible before cgroup_task_release()/put_task_struct_rcu_user()). The tasks after cgroup_task_release() and before cgroup_task_free() are subject to race when they may or may not have ->usage count > 0. The race window is between css_task_iter_next() invocations when css_set_lock is released and we may arrive at a new ->task_pos. The iterator should not attempt to resurrect tasks whose ->usage count dropped to zero. (When that happens, __put_task_struct_rcu_cb() is already imminent and the returned task_struct would could be used after free.) As for the fix, we cannot simply check the signal->live count of a task on the dying list because that won't distinguish regular zombies waiting to be reaped from RCU remnant tasks that are going to be free'd. Therefore add an extra check to rule out ->usage==0 tasks from any iteration. The repeat: loop in css_task_iter_advance() doesn't consider ->usage count, so add a new loop to css_task_iter_next() to skip de-used tasks on the dying_list. Rough illustration of the possible race R (reader of cgroup.procs) T (thread) L (group leader) --------------------------------- -------------------------------- -------------------------------- L exits, signal->live > 0 cgroup_task_dead(L) css_set_skip_task_iters() // skips only cset->tasks list_add_tail(&L->cg_list, &cset->dying_tasks) css_task_iter_next() take css_set_lock css_task_iter_advance() leader && signal->live != 0 => it->task_pos = &L->cg_list release css_set_lock T exits --signal->live == 0 cgroup_task_dead(T) // css_set_lock release_task(T) cgroup_task_release(T) release_task(L) // zap_leader cgroup_task_release(L) put_task_struct_rcu_user(L) ...RCU... put_task_struct(L) L->usage = 0 /* L still on dying_tasks */ ...RCU... __put_task_struct(L) css_task_iter_next() // another iteration take css_set_lock it->task_pos = &L->cg_list get_task_struct(L) => addition on 0 drop css_set_lock cgroup_task_free(L) css_set_skip_task_iters() // dying skip comes too late free_task(L) cgroup_procs_show() task_pid_vnr(L) Fixes: 260fbcb92bbea ("cgroup: Move dying_tasks cleanup from cgroup_task_release() to cgroup_task_free()") Cc: stable@vger.kernel.org # v6.19+ Link: https://lists.debian.org/debian-kernel/2026/08/msg00220.html Reported-by: Noah Elias Feldt Reported-by: Salvatore Bonaccorso Tested-by: Salvatore Bonaccorso Signed-off-by: Michal Koutný Signed-off-by: Tejun Heo --- kernel/cgroup/cgroup.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) (limited to 'kernel') diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c index 353c8f83439a..a3d363502b7b 100644 --- a/kernel/cgroup/cgroup.c +++ b/kernel/cgroup/cgroup.c @@ -5207,10 +5207,13 @@ struct task_struct *css_task_iter_next(struct css_task_iter *it) if (it->flags & CSS_TASK_ITER_SKIPPED) css_task_iter_advance(it); - if (it->task_pos) { + while (it->task_pos && !it->cur_task) { it->cur_task = list_entry(it->task_pos, struct task_struct, cg_list); - get_task_struct(it->cur_task); + /* a task on dying_tasks with zero refcount is only valid for + * RCU readers, not even interesting for + * CSS_TASK_ITER_WITH_DEAD, find another one */ + it->cur_task = tryget_task_struct(it->cur_task); css_task_iter_advance(it); } -- cgit v1.2.3 From 82431877d837a6c2593efd8e66ba28b35a220ca4 Mon Sep 17 00:00:00 2001 From: Kuniyuki Iwashima Date: Sat, 5 Sep 2026 23:36:30 +0000 Subject: sysctl: Check range in proc_dointvec_ms_jiffies_minmax Add the range check to do_proc_int_conv_ms_jiffies_minmax that commit d174174c6776 ("sysctl: replace SYSCTL_INT_CONV_CUSTOM macro with functions") incorrectly removed. Fixes: d174174c6776 ("sysctl: replace SYSCTL_INT_CONV_CUSTOM macro with functions") Signed-off-by: Kuniyuki Iwashima Signed-off-by: Joel Granados --- kernel/time/jiffies.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'kernel') diff --git a/kernel/time/jiffies.c b/kernel/time/jiffies.c index 213ae1d6a014..70926b73905a 100644 --- a/kernel/time/jiffies.c +++ b/kernel/time/jiffies.c @@ -181,7 +181,7 @@ static int do_proc_int_conv_ms_jiffies_minmax(bool *negp, ulong *u_ptr, int *k_ptr, int dir, const struct ctl_table *tbl) { - return proc_int_conv(negp, u_ptr, k_ptr, dir, tbl, false, + return proc_int_conv(negp, u_ptr, k_ptr, dir, tbl, true, sysctl_u2k_int_conv_ms, sysctl_k2u_int_conv_ms); } -- cgit v1.2.3 From 318012c56576e09806747f64f89f8f3cde1f999f Mon Sep 17 00:00:00 2001 From: Kuniyuki Iwashima Date: Sat, 5 Sep 2026 23:36:31 +0000 Subject: sysctl: Check range in do_proc_ulong_conv_ms_jiffies Add the range check back to do_proc_ulong_conv_ms_jiffies that commit b96b5c6708ea ("sysctl: Replace do_proc_do{int,ulong,uint}vec with do_proc_vec") incorrectly removed. Append "_minmax" to the end of do_proc_ulong_conv_ms_jiffies so it is clear that there should be a range check. Fixes: b96b5c6708ea ("sysctl: Replace do_proc_do{int,ulong,uint}vec with do_proc_vec") Signed-off-by: Kuniyuki Iwashima Signed-off-by: Joel Granados --- kernel/time/jiffies.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) (limited to 'kernel') diff --git a/kernel/time/jiffies.c b/kernel/time/jiffies.c index 70926b73905a..41f88ebac74a 100644 --- a/kernel/time/jiffies.c +++ b/kernel/time/jiffies.c @@ -195,10 +195,10 @@ static int sysctl_k2u_ulong_conv_ms(ulong *u_ptr, const ulong *k_ptr) return proc_ulong_k2u_conv_kop(u_ptr, k_ptr, sysctl_jiffies_to_msecs); } -static int do_proc_ulong_conv_ms_jiffies(bool *negp, ulong *u_ptr, ulong *k_ptr, - int dir, const struct ctl_table *tbl) +static int do_proc_ulong_conv_ms_jiffies_minmax(bool *negp, ulong *u_ptr, ulong *k_ptr, + int dir, const struct ctl_table *tbl) { - return proc_ulong_conv(u_ptr, k_ptr, dir, tbl, false, + return proc_ulong_conv(u_ptr, k_ptr, dir, tbl, true, sysctl_u2k_ulong_conv_ms, sysctl_k2u_ulong_conv_ms); } @@ -229,8 +229,8 @@ static int do_proc_int_conv_ms_jiffies_minmax(bool *negp, ulong *u_ptr, return -ENOSYS; } -static int do_proc_ulong_conv_ms_jiffies(bool *negp, ulong *u_ptr, ulong *k_ptr, - int dir, const struct ctl_table *tbl) +static int do_proc_ulong_conv_ms_jiffies_minmax(bool *negp, ulong *u_ptr, ulong *k_ptr, + int dir, const struct ctl_table *tbl) { return -ENOSYS; } @@ -333,7 +333,7 @@ int proc_doulongvec_ms_jiffies_minmax(const struct ctl_table *table, int dir, void *buffer, size_t *lenp, loff_t *ppos) { return proc_doulongvec_conv(table, dir, buffer, lenp, ppos, - do_proc_ulong_conv_ms_jiffies); + do_proc_ulong_conv_ms_jiffies_minmax); } EXPORT_SYMBOL(proc_doulongvec_ms_jiffies_minmax); -- cgit v1.2.3 From afdf35cfae0d039a4a6c907fa5d8391f1ef0a0aa Mon Sep 17 00:00:00 2001 From: Joel Granados Date: Thu, 10 Sep 2026 12:22:16 +0200 Subject: sysctl: Fix type truncation in sysctl_msec_to_jiffies Return MAX_JIFFY_OFFSET for all the values truncated when val (u64) is passed to msecs_to_jiffies (u32). This aligns with how very large millisecond values get translated into MAX_JIFFY_OFFSET. Fixes: b96b5c6708ea ("sysctl: Replace do_proc_do{int,ulong,uint}vec with do_proc_vec") Suggested-by: Kuniyuki Iwashima Signed-off-by: Joel Granados --- kernel/time/jiffies.c | 2 ++ 1 file changed, 2 insertions(+) (limited to 'kernel') diff --git a/kernel/time/jiffies.c b/kernel/time/jiffies.c index 41f88ebac74a..80c354811538 100644 --- a/kernel/time/jiffies.c +++ b/kernel/time/jiffies.c @@ -136,6 +136,8 @@ static int sysctl_k2u_int_conv_userhz(bool *negp, ulong *u_ptr, const int *k_ptr static ulong sysctl_msecs_to_jiffies(const ulong val) { + if (val > jiffies_to_msecs(MAX_JIFFY_OFFSET)) + return MAX_JIFFY_OFFSET; return msecs_to_jiffies(val); } -- cgit v1.2.3 From 9a0b159ff18c8f6fcf982bb81e15a9ceb14db43a Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Mon, 14 Sep 2026 22:12:34 -1000 Subject: sched_ext: scx_qmap: Restore unused idle claims from ops.dispatch() scx_qmap tracks idle cids itself. pick_direct_dispatch_cid() claims a cid by clearing its bit and the task is inserted into that cid's local DSQ, which kicks the CPU. When the task does not arrive, for example because the insert fell back to the global DSQ after an affinity change, the CPU wakes, finds nothing and picks idle again. That is not an idle transition, so ops.update_idle() is not called and the cid stays marked busy until an unrelated task runs on it. Restore the claim from ops.dispatch(). The kick guarantees a dispatch on the kicked CPU, and when it finds nothing to run with a NULL @prev, the CPU is going back to idle. Document the pattern in ops.update_idle(), which reports only actual transitions. Signed-off-by: Tejun Heo Reviewed-by: Andrea Righi Cc: Andrea Righi --- kernel/sched/ext/internal.h | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'kernel') diff --git a/kernel/sched/ext/internal.h b/kernel/sched/ext/internal.h index 076a351bb3f2..0adaf649d5e0 100644 --- a/kernel/sched/ext/internal.h +++ b/kernel/sched/ext/internal.h @@ -572,6 +572,12 @@ struct sched_ext_ops { * * Specify the %SCX_OPS_KEEP_BUILTIN_IDLE flag to keep the built-in idle * tracking. + * + * Only actual transitions are reported. A CPU that is claimed with an + * idle pick and kicked but dispatches no task returns to idle without a + * transition. A scheduler tracking idle CPUs itself must restore the + * idle state from ops.dispatch() when it returns without the next task + * to run. */ void (*update_idle)(s32 cpu, bool idle); -- cgit v1.2.3 From a9e3760b0838299649c0d57cca44daaf40ba3c33 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Mon, 14 Sep 2026 22:12:34 -1000 Subject: sched_ext: Maintain an online cid mask in the scheduler arena Schedulers on the default cid mapping treat [0, nr_online_cids) as the online set and restart on hotplug. Schedulers that install their own mapping with scx_bpf_cid_override() have no way to learn which cids are online: the count no longer identifies members and the CPU-form cpumask is unusable from cid programs. This is an obvious hole in the cid API. Add scx_bpf_online_cmask(), a kernel-maintained cmask in the scheduler's arena, allocated alongside the per-CPU scratch masks and populated after the cid mapping is finalized and before ops.init(), for child schedulers too. The pointer stays valid through ops.exit() with no reference to take. It is the arena offset as a void pointer, the same form struct_ops arena arguments arrive in. The verifier types the void return as a scalar for the program's arena cast. The mask follows the SCX hotplug notifications: seeded from cpu_active_mask and updated before ops.cid_online/offline() runs, so it lags cpu_online_mask only inside a hotplug transition. Updates walk the scheduler list under the lock that also serializes unlinking. Reads are live, not atomic snapshots. Root initialization excludes hotplug. v2: Reworded the getter kerneldoc (Andrea Righi). Signed-off-by: Tejun Heo Reviewed-by: Andrea Righi --- kernel/sched/ext/ext.c | 75 +++++++++++++++++++++++++++++++++++++++++---- kernel/sched/ext/internal.h | 3 +- kernel/sched/ext/sub.c | 10 +++--- 3 files changed, 77 insertions(+), 11 deletions(-) (limited to 'kernel') diff --git a/kernel/sched/ext/ext.c b/kernel/sched/ext/ext.c index 83999203a63a..70b711c4de6e 100644 --- a/kernel/sched/ext/ext.c +++ b/kernel/sched/ext/ext.c @@ -3670,8 +3670,20 @@ static void handle_hotplug(struct rq *rq, bool online) s16 *tbl = rcu_dereference_check(scx_cpu_to_cid_tbl, lockdep_is_cpus_held()); - if (tbl) + if (tbl) { + struct scx_sched *pos; + cpu_or_cid = tbl[cpu]; + + guard(raw_spinlock_irqsave)(&scx_sched_lock); + list_for_each_entry(pos, &scx_sched_all, all) { + struct scx_cmask *mask = pos->online_cmask; + + if (mask) + __assign_bit(cpu_or_cid, (unsigned long *)mask->bits, + online); + } + } } if (online && SCX_HAS_OP(sch, cpu_online)) @@ -5280,12 +5292,17 @@ static void free_exit_info(struct scx_exit_info *ei); static const char *scx_exit_reason(enum scx_exit_kind kind); static bool scx_claim_exit(struct scx_sched *sch, enum scx_exit_kind kind); -s32 scx_set_cmask_scratch_alloc(struct scx_sched *sch) +s32 scx_alloc_kern_arena_objs(struct scx_sched *sch) { size_t size = struct_size_t(struct scx_cmask, bits, SCX_CMASK_NR_WORDS(num_possible_cpus())); + struct scx_cmask *online; + struct scx_cmask_ref ref; int cpu; + /* hotplug stays excluded until the online mask is published */ + lockdep_assert_cpus_held(); + if (!sch->is_cid_type || !sch->arena_pool) return 0; @@ -5301,15 +5318,28 @@ s32 scx_set_cmask_scratch_alloc(struct scx_sched *sch) return -ENOMEM; scx_cmask_init(*slot, 0, num_possible_cpus()); } + + /* pack the online mask alongside the scratch masks */ + online = scx_arena_alloc(sch, size); + if (!online) + return -ENOMEM; + + scoped_guard(rcu) { + scx_cmask_ref_init_kern(sch, online, 0, num_possible_cpus(), &ref); + scx_cmask_ref_from_cpumask(&ref, cpu_active_mask); + } + sch->online_cmask = online; + return 0; } -static void scx_set_cmask_scratch_free(struct scx_sched *sch) +static void scx_free_kern_arena_objs(struct scx_sched *sch) { size_t size = struct_size_t(struct scx_cmask, bits, SCX_CMASK_NR_WORDS(num_possible_cpus())); int cpu; + scx_arena_free(sch, sch->online_cmask, size); if (!sch->set_cmask_scratch) return; @@ -5396,7 +5426,7 @@ static void scx_sched_free_rcu_work(struct work_struct *work) rhashtable_free_and_destroy(&sch->dsq_hash, NULL, NULL); free_exit_info(sch->exit_info); - scx_set_cmask_scratch_free(sch); + scx_free_kern_arena_objs(sch); scx_arena_pool_destroy(sch); if (sch->arena_map) bpf_map_put(sch->arena_map); @@ -7601,7 +7631,7 @@ static void scx_root_enable_workfn(struct kthread_work *work) goto err_disable; } - ret = scx_set_cmask_scratch_alloc(sch); + ret = scx_alloc_kern_arena_objs(sch); if (ret) { cpus_read_unlock(); goto err_disable; @@ -10338,13 +10368,45 @@ __bpf_kfunc u32 scx_bpf_nr_cids(void) * hotplug, which lets schedulers treat [0, nr_online_cids) as the online * range. Schedulers that prefer to handle hotplug without a restart should * install a custom mapping via scx_bpf_cid_override() and track onlining - * through the ops.cid_online / ops.cid_offline callbacks. + * through the ops.cid_online / ops.cid_offline callbacks, starting from the + * mask scx_bpf_online_cmask() returns. */ __bpf_kfunc u32 scx_bpf_nr_online_cids(void) { return num_online_cpus(); } +/** + * scx_bpf_online_cmask - Return the online cid mask in the scheduler arena + * @aux: implicit BPF argument to access bpf_prog_aux hidden from BPF progs + * + * Return a kernel-maintained cmask covering [0, scx_bpf_nr_cids()), or NULL if + * the calling program is not associated with a live cid-form scheduler or the + * mask is not allocated yet, as in ops.init_cids(). Treat the mask as read-only + * even though arena memory stays writable by the BPF scheduler. The mask + * follows the SCX hotplug notifications: a cid's bit is updated before + * ops.cid_online/offline() runs for it. The pointer is valid from ops.init() + * through ops.exit(). Root ops.init() runs with hotplug excluded. Other + * contexts can observe concurrent updates. + */ +__bpf_kfunc const void *scx_bpf_online_cmask(const struct bpf_prog_aux *aux) +{ + struct scx_sched *sch; + struct scx_cmask *online; + + guard(rcu)(); + + sch = scx_prog_sched(aux); + if (unlikely(!sch)) + return NULL; + online = sch->online_cmask; + if (unlikely(!online)) + return NULL; + + /* BPF rebases by the low 32 bits, like __arena callback args */ + return (void *)((unsigned long)online - sch->arena_kern_base); +} + /** * scx_bpf_this_cid - Return the cid of the CPU this program is running on * @@ -10708,6 +10770,7 @@ BTF_ID_FLAGS(func, scx_bpf_nr_node_ids) BTF_ID_FLAGS(func, scx_bpf_nr_cpu_ids) BTF_ID_FLAGS(func, scx_bpf_nr_cids) BTF_ID_FLAGS(func, scx_bpf_nr_online_cids) +BTF_ID_FLAGS(func, scx_bpf_online_cmask, KF_IMPLICIT_ARGS | KF_ARENA_RET) BTF_ID_FLAGS(func, scx_bpf_this_cid) BTF_ID_FLAGS(func, scx_bpf_get_possible_cpumask, KF_ACQUIRE) BTF_ID_FLAGS(func, scx_bpf_get_online_cpumask, KF_ACQUIRE) diff --git a/kernel/sched/ext/internal.h b/kernel/sched/ext/internal.h index 0adaf649d5e0..3464e0f113c1 100644 --- a/kernel/sched/ext/internal.h +++ b/kernel/sched/ext/internal.h @@ -1561,6 +1561,7 @@ struct scx_sched { * and passes it to the callback's __arena argument. */ struct scx_cmask * __percpu *set_cmask_scratch; + struct scx_cmask *online_cmask; DECLARE_BITMAP(has_op, SCX_OPI_END); @@ -2087,7 +2088,7 @@ void scx_disable_and_exit_task(struct scx_sched *sch, struct task_struct *p); void scx_cgroup_lock(void); void scx_cgroup_unlock(void); #endif -s32 scx_set_cmask_scratch_alloc(struct scx_sched *sch); +s32 scx_alloc_kern_arena_objs(struct scx_sched *sch); void scx_disable_bypass_dsp(struct scx_sched *sch); void scx_bypass(struct scx_sched *sch, bool bypass); s32 scx_link_sched(struct scx_sched *sch); diff --git a/kernel/sched/ext/sub.c b/kernel/sched/ext/sub.c index 385302d19914..f7aeb1488566 100644 --- a/kernel/sched/ext/sub.c +++ b/kernel/sched/ext/sub.c @@ -1805,6 +1805,12 @@ void scx_sub_enable_workfn(struct kthread_work *work) goto err_disable; } + scoped_guard(cpus_read_lock) { + ret = scx_alloc_kern_arena_objs(sch); + if (ret) + goto err_disable; + } + if (sch->ops.init) { ret = SCX_CALL_OP_RET(sch, init, NULL); if (ret) { @@ -1815,10 +1821,6 @@ void scx_sub_enable_workfn(struct kthread_work *work) sch->exit_info->flags |= SCX_EFLAG_INITIALIZED; } - ret = scx_set_cmask_scratch_alloc(sch); - if (ret) - goto err_disable; - struct scx_sub_attach_args sub_attach_args = { .ops = &sch->ops, .cgroup_path = sch->cgrp_path, -- cgit v1.2.3 From 7de9a6fb44eae4f05e68c805d58b9c618815adfa Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Tue, 15 Sep 2026 12:34:44 -1000 Subject: sched_ext: Wait for SCX_OPSS_DISPATCHING before reenqueueing a task ebf1ccff79c4 ("sched_ext: Fix ops.dequeue() semantics") moved the final ops_state store in scx_dispatch_enqueue() after the DSQ unlock so that the custody update and ops.dequeue() precede it. A task can thus be found on a DSQ while still SCX_OPSS_DISPATCHING. The dequeue and core-sched pick paths wait for the state to clear in ops_dequeue() but the reenqueue paths don't. A reenqueue in that window runs ops.enqueue() and sets SCX_OPSS_QUEUED before the dispatch has completed. The dispatcher's final store then overwrites it with SCX_OPSS_NONE and finish_dispatch() drops every later dispatch of the task. Wait for SCX_OPSS_DISPATCHING to clear before dequeueing a task for reenqueue, the same way ops_dequeue() does. Fixes: ebf1ccff79c4 ("sched_ext: Fix ops.dequeue() semantics") Cc: stable@vger.kernel.org # v7.1+ Signed-off-by: Tejun Heo Reviewed-by: Andrea Righi --- kernel/sched/ext/ext.c | 13 +++++++++++++ kernel/sched/ext/internal.h | 1 + kernel/sched/ext/sub.c | 1 + 3 files changed, 15 insertions(+) (limited to 'kernel') diff --git a/kernel/sched/ext/ext.c b/kernel/sched/ext/ext.c index 70b711c4de6e..725b890fcab9 100644 --- a/kernel/sched/ext/ext.c +++ b/kernel/sched/ext/ext.c @@ -4404,6 +4404,17 @@ static bool local_task_should_reenq(struct rq *rq, struct task_struct *p, return *reenq_flags & SCX_REENQ_ANY; } +/* + * The dispatcher stores the final ops_state after dropping the DSQ lock, so @p + * can be found on a DSQ while still %SCX_OPSS_DISPATCHING. Reenqueueing @p + * before that store lands would have it clobber the new %SCX_OPSS_QUEUED. + */ +void scx_reenq_wait_dispatching(struct task_struct *p) +{ + if (unlikely(atomic_long_read_acquire(&p->scx.ops_state) == SCX_OPSS_DISPATCHING)) + wait_ops_state(p, SCX_OPSS_DISPATCHING); +} + static u32 reenq_local(struct scx_sched *sch, struct rq *rq, u64 reenq_flags) { LIST_HEAD(tasks); @@ -4447,6 +4458,7 @@ static u32 reenq_local(struct scx_sched *sch, struct rq *rq, u64 reenq_flags) if (!local_task_should_reenq(rq, p, &reenq_flags, &reason)) continue; + scx_reenq_wait_dispatching(p); scx_dispatch_dequeue(rq, p); if (WARN_ON_ONCE(p->scx.flags & SCX_TASK_REENQ_REASON_MASK)) @@ -4570,6 +4582,7 @@ static void reenq_user(struct rq *rq, struct scx_dispatch_q *dsq, u64 reenq_flag } /* @p is on @dsq, its rq and @dsq are locked */ + scx_reenq_wait_dispatching(p); dispatch_dequeue_locked(p, dsq); raw_spin_unlock(&dsq->lock); diff --git a/kernel/sched/ext/internal.h b/kernel/sched/ext/internal.h index 3464e0f113c1..115c96fbf932 100644 --- a/kernel/sched/ext/internal.h +++ b/kernel/sched/ext/internal.h @@ -2078,6 +2078,7 @@ void scx_kick_cpu(struct scx_sched *sch, s32 cpu, u64 flags); u64 __scx_bpf_now(struct rq *rq); void schedule_dsq_reenq(struct scx_sched *sch, struct scx_dispatch_q *dsq, u64 reenq_flags, struct rq *locked_rq); +void scx_reenq_wait_dispatching(struct task_struct *p); int __scx_init_task(struct scx_sched *sch, struct task_struct *p, struct cgroup *cgrp, bool fork); void scx_enable_task(struct scx_sched *sch, struct task_struct *p); diff --git a/kernel/sched/ext/sub.c b/kernel/sched/ext/sub.c index f7aeb1488566..a30c965b175d 100644 --- a/kernel/sched/ext/sub.c +++ b/kernel/sched/ext/sub.c @@ -801,6 +801,7 @@ void scx_reenq_reject(struct rq *rq) if (WARN_ON_ONCE(p->migration_pending)) continue; + scx_reenq_wait_dispatching(p); scx_dispatch_dequeue(rq, p); if (WARN_ON_ONCE(p->scx.flags & SCX_TASK_REENQ_REASON_MASK)) -- cgit v1.2.3 From b61b6f95d6722ddbbbd09e689fa41b55fd36f9a5 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Fri, 11 Sep 2026 11:04:47 +0200 Subject: futex: Also allocate private hash on vfork() As Jann demonstrated, it is entirely feasible to access the mm through vfork(). Therefore we need to allocate a private hash on vfork() as well as any other CLONE_VM user. Specifically, it must be avoided to have (private) futex waiters before allocating the private hash. Fixes: ee9dce44362b ("futex: Drop CLONE_THREAD requirement for private default hash alloc") Reported-by: Jann Horn Signed-off-by: Peter Zijlstra (Intel) Link: https://patch.msgid.link/20260911090447.GT788244@noisy.programming.kicks-ass.net --- kernel/fork.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'kernel') diff --git a/kernel/fork.c b/kernel/fork.c index a5934a317634..5ef413368912 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -1996,9 +1996,9 @@ static bool need_futex_hash_allocate_default(u64 clone_flags) { /* * Allocate a default futex hash for any sibling that will - * share the parent's mm, except vfork. + * share the parent's mm. */ - return (clone_flags & (CLONE_VM | CLONE_VFORK)) == CLONE_VM; + return clone_flags & CLONE_VM; } /* -- cgit v1.2.3 From d2710c8d938ae6a825a6463158e6e6f31eac792a Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Fri, 11 Sep 2026 11:09:12 +0200 Subject: signal: Prevent exec() race Hyunwoo debugged the following KASAN UAF splat: BUG: KASAN: slab-use-after-free in __send_signal_locked+0xb27/0xba0 Write of size 8 at addr ffff888007ed80c8 by task poc/79 ... Call Trace: __send_signal_locked+0xb27/0xba0 do_send_sig_info+0xa7/0x160 do_send_specific+0x76/0xa0 __x64_sys_tgkill+0x193/0x270 ... Allocated by task 80: do_timer_create+0x1a4/0x1030 __x64_sys_timer_create+0x145/0x190 ... Freed by task 12: kmem_cache_free_bulk+0x1f8/0x4a0 kvfree_rcu_bulk+0x14f/0x1c0 kfree_rcu_work+0x128/0x1a0 ... Last potentially related work creation: kvfree_call_rcu+0x39/0x390 __flush_itimer_signals+0x211/0x320 flush_itimer_signals+0x47/0x90 begin_new_exec+0xa6b/0x28c0 It turned out that this happens with a non-leader exec() as Hyunwoo explained: de_thread() calls exchange_tids() before release_task(leader), so the struct pid held by a SIGEV_THREAD_ID timer created against the leader's tid now points to the thread which called execve(). pid_task() returns that thread and lock_task_sighand() on it succeeds. If the timer signal is blocked, its sigqueue stays queued on the leader's task::pending. The next expiry of that timer can then run while release_task() flushes the queue. posixtimer_send_sigqueue() checks whether the sigqueue is already queued with a plain list_empty(), which only reads list_head::next. list_del_init() is not atomic and INIT_LIST_HEAD() stores list_head::next before list_head::prev, so the check can pass in between. list_add_tail() queues the entry on the task::pending of the live thread, and the list_head::prev store from the flush then overwrites the list_head::prev link that list_add_tail() has just set. __flush_itimer_signals() does not undo that either. With list_head::prev pointing at the entry itself, its list_del_init() only stores the same values again, so the entry is not removed from the list. It is still there after the last reference is dropped and the timer is freed by RCU, and the list_add_tail() of a later tgkill() follows that list_head::prev into the freed timer. This problem surfaced with the recent commit which moved the sigqueue flush out of the sighand lock held region. Hyonwoo proposed to fix this by using list_del_init_careful(), but that just papers over the problem. After some disucssions and various attempts to solve it, Eric pointed out that there is no reason to flush task::pending late in release_task() and it should be done in exit_signals() already. As nothing can collect and deliver signals which are queued in a dying task's pending queue, there is no reason to delay it further. But it has to be ensured that no signals can be queued into it after that point. exit_signals() sets PF_EXITING in task::flags, which can be used as an indicator for this. Cure it by: - Preventing signal queueing for task private signals (PIDTYPE_PID) when the task has PF_EXITING set in __send_signal_locked() and in posixtimer_send_sigqueue(). - Protecting the unlocked setting of PF_EXITING in exit_signals() for the task group empty and the group exit case with sighand lock - Flushing task::pending signals right there. Optimize that by moving the whole pending list to an on-stack list head under sighand lock and free the signals without the lock held. There has been quite some discussion about the lockless flush and the non-leader exec case on weakly ordered systems. The problem is that a third party which tries to send a posix timer signal relies on the PID lookup to find the target task and that lookup might result in the new leader when the signal was originaly directed to the old leader. In case that the signal was queued on the old leader then the lockless flush raised a concern over the following situation: old_leader new_leader third party A: flush_list() // list_del_init() stores to sigqueue LOCK (tasklist) old_leader->exit_state = EXIT_ZOMBIE; B: UNLOCK (tasklist) C: LOCK (tasklist) if (old_leader->exit_state) transfer_tids() D: store PID posix_timer_send_sigqueue() // Observes #D so t = new_leader E: t = get_target() F: LOCK (sighand) G: if (list_empty(sigqueue)) list_add(sigqueue) The concern was that the third party might observe #D but not observe #A and therefore would proceed to #G while the list_del() stores (#A) in flush_list() are not visible yet, which could result in list corruption. That would be possible if looking at it solely from a RELEASE+ACQUIRE ordering point of view, but B-C is a UNLOCK+LOCK hand-over, which is not the same as RELEASE+ACQUIRE: RELEASE+ACQUIRE: RCpc, only the CPUs involved agree on the ordering UNLOCK+LOCK: RCtso, the hand-over is store-ordering As B-C is UNLOCK+LOCK, which is RCtso and that does impose store order, A stores must happen before the D store. Combine with E-F, which has a data dependency from the LOAD to the LOCK and thereby constraints later LOADs, those sigqueue loads in G that come after F must in fact observe the A stores. Fixes: fb3bbcfe344e ("exit: change the release_task() paths to call flush_sigqueue() lockless") Reported-by: Hyunwoo Kim Debugged-by: Hyunwoo Kim Suggested-by: "Eric W. Biederman" Signed-off-by: Thomas Gleixner Tested-by: Kijo Park Reviewed-by: Oleg Nesterov Reviewed-by: Frederic Weisbecker Cc: stable@vger.kernel.org Link: https://patch.msgid.link/20260911090541.572536604@kernel.org Closes: https://patch.msgid.link/aok1rdkBgZsynHZB@v4bel --- kernel/exit.c | 11 +++--- kernel/signal.c | 115 +++++++++++++++++++++++++++++++++++++++++--------------- 2 files changed, 91 insertions(+), 35 deletions(-) (limited to 'kernel') diff --git a/kernel/exit.c b/kernel/exit.c index 4e028f157597..424c44a42a4d 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -302,12 +302,13 @@ repeat: free_pids(post.pids); release_thread(p); /* - * This task was already removed from the process/thread/pid lists - * and lock_task_sighand(p) can't succeed. Nobody else can touch - * ->pending or, if group dead, signal->shared_pending. We can call - * flush_sigqueue() lockless. + * This task was already removed from the process/thread/pid lists and + * lock_task_sighand(p) can't succeed. If it's the group leader then + * flush tsk->signal->shared_pending. tsk->pending has been flushed + * already in exit_signals(). Nothing else can touch + * signal->shared_pending anymore, so flush_sigqueue() can be invoked + * lockless. */ - flush_sigqueue(&p->pending); if (thread_group_leader(p)) flush_sigqueue(&p->signal->shared_pending); diff --git a/kernel/signal.c b/kernel/signal.c index ec30550951ec..d31ebcb6ed4d 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -457,18 +457,42 @@ static void __sigqueue_free(struct sigqueue *q) kmem_cache_free(sigqueue_cachep, q); } -void flush_sigqueue(struct sigpending *queue) +/* + * flush_sigqueue_list() can only be invoked without holding sighand::siglock in + * the following cases: + * + * 1) When flushing task::pending _after_ setting task::flags PF_EXITING + * + * All functions which try to send a signal to @task will observe PF_EXITING + * and drop the signal. + * + * 2) When flushing task::signal::shared_pending _after_ the last task in a + * thread group was unhashed and task::sighand is NULL. + * + * Nothing can queue a signal anymore because sighand is NULL. + */ +static void flush_sigqueue_list(struct list_head *head) { - struct sigqueue *q; + struct sigqueue *q, *tmp; - sigemptyset(&queue->signal); - while (!list_empty(&queue->list)) { - q = list_entry(queue->list.next, struct sigqueue , list); + list_for_each_entry_safe(q, tmp, head, list) { list_del_init(&q->list); __sigqueue_free(q); } } +void flush_sigqueue(struct sigpending *queue) +{ + sigemptyset(&queue->signal); + flush_sigqueue_list(&queue->list); +} + +static void sigqueue_dequeue_pending(struct sigpending *queue, struct list_head *head) +{ + sigemptyset(&queue->signal); + list_splice_init(&queue->list, head); +} + /* * Flush all pending signals for this kthread. */ @@ -1019,6 +1043,21 @@ static inline bool legacy_queue(struct sigpending *signals, int sig) return (sig < SIGRTMIN) && sigismember(&signals->signal, sig); } +/* + * When PF_EXITING is set the task is on the way out and has t::pending + * flushed already. Prevent queueing of PIDTYPE_PID signals as they would + * be leaked. + */ +static inline bool task_can_queue_signal(struct task_struct *t, enum pid_type type) +{ + lockdep_assert_held(&t->sighand->siglock); + + if (!(t->flags & PF_EXITING)) + return true; + + return type != PIDTYPE_PID; +} + static int __send_signal_locked(int sig, struct kernel_siginfo *info, struct task_struct *t, enum pid_type type, bool force) { @@ -1030,6 +1069,10 @@ static int __send_signal_locked(int sig, struct kernel_siginfo *info, lockdep_assert_held(&t->sighand->siglock); result = TRACE_SIGNAL_IGNORED; + + if (!task_can_queue_signal(t, type)) + goto ret; + if (!prepare_signal(sig, t, force)) goto ret; @@ -1980,11 +2023,25 @@ static inline struct task_struct *posixtimer_get_target(struct k_itimer *tmr) struct task_struct *t = pid_task(tmr->it_pid, tmr->it_pid_type); if (t && tmr->it_pid_type != PIDTYPE_PID && - same_thread_group(t, current) && !current->exit_state) + same_thread_group(t, current) && !(current->flags & PF_EXITING)) t = current; return t; } +/* + * Find the target task for the POSIX timer signal and prevent that a + * PIDTYPE_PID signal is queued on a task which has PF_EXITING set. + */ +static inline struct task_struct *posixtimer_get_unignore_target(struct k_itimer *tmr) +{ + struct task_struct *t = posixtimer_get_target(tmr); + + if (t && task_can_queue_signal(t, tmr->it_pid_type)) + return t; + + return NULL; +} + void posixtimer_send_sigqueue(struct k_itimer *tmr) { struct sigqueue *q = &tmr->sigq; @@ -2002,6 +2059,9 @@ void posixtimer_send_sigqueue(struct k_itimer *tmr) if (!likely(lock_task_sighand(t, &flags))) return; + if (!task_can_queue_signal(t, tmr->it_pid_type)) + goto unlock; + /* * Update @tmr::sigqueue_seq for posix timer signals with sighand * locked to prevent a race against dequeue_signal(). @@ -2093,6 +2153,7 @@ void posixtimer_send_sigqueue(struct k_itimer *tmr) result = TRACE_SIGNAL_DELIVERED; out: trace_signal_generate(sig, &q->info, t, tmr->it_pid_type != PIDTYPE_PID, result); +unlock: unlock_task_sighand(t, &flags); } @@ -2148,7 +2209,7 @@ static void posixtimer_sig_unignore(struct task_struct *tsk, int sig) * has exited by now, drop the reference count. */ guard(rcu)(); - target = posixtimer_get_target(tmr); + target = posixtimer_get_unignore_target(tmr); if (target) posixtimer_queue_sigqueue(&tmr->sigq, target, tmr->it_pid_type); else @@ -3132,42 +3193,36 @@ static void retarget_shared_pending(struct task_struct *tsk, sigset_t *which) void exit_signals(struct task_struct *tsk) { + LIST_HEAD(sigq_list); int group_stop = 0; - sigset_t unblocked; /* * @tsk is about to have PF_EXITING set - lock out users which - * expect stable threadgroup. + * expect a stable threadgroup. */ cgroup_threadgroup_change_begin(tsk); - if (thread_group_empty(tsk) || (tsk->signal->flags & SIGNAL_GROUP_EXIT)) { + scoped_guard(spinlock_irq, &tsk->sighand->siglock) { tsk->flags |= PF_EXITING; - cgroup_threadgroup_change_end(tsk); - return; - } - spin_lock_irq(&tsk->sighand->siglock); - /* - * From now this task is not visible for group-wide signals, - * see wants_signal(), do_signal_stop(). - */ - tsk->flags |= PF_EXITING; + sigqueue_dequeue_pending(&tsk->pending, &sigq_list); - cgroup_threadgroup_change_end(tsk); + if (task_sigpending(tsk) && !thread_group_empty(tsk) && + !(tsk->signal->flags & SIGNAL_GROUP_EXIT)) { + sigset_t unblocked = tsk->blocked; - if (!task_sigpending(tsk)) - goto out; + signotset(&unblocked); + retarget_shared_pending(tsk, &unblocked); - unblocked = tsk->blocked; - signotset(&unblocked); - retarget_shared_pending(tsk, &unblocked); + if (unlikely(tsk->jobctl & JOBCTL_STOP_PENDING) && + task_participate_group_stop(tsk)) + group_stop = CLD_STOPPED; + } + } - if (unlikely(tsk->jobctl & JOBCTL_STOP_PENDING) && - task_participate_group_stop(tsk)) - group_stop = CLD_STOPPED; -out: - spin_unlock_irq(&tsk->sighand->siglock); + cgroup_threadgroup_change_end(tsk); + + flush_sigqueue_list(&sigq_list); /* * If group stop has completed, deliver the notification. This -- cgit v1.2.3 From df5cdc2c832ca4e8a6d774596b9005558761a403 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Wed, 16 Sep 2026 12:00:24 -1000 Subject: sched_ext: Derive SCX_RQ_IN_WAKEUP from the core enqueue flags schedule_deferred_locked() skips scheduling a deferred action while SCX_RQ_IN_WAKEUP is set and relies on the task_woken_scx() call that follows a wakeup enqueue to run it. enqueue_task_scx() sets the flag from the merged enqueue flags, which include the flags stashed for a remote activation. move_remote_task_to_local_dsq() thus sets SCX_RQ_IN_WAKEUP on the destination rq when the moved task was woken up, although no task_woken_scx() follows that activation. An IMMED insert into a busy destination requests a local reenqueue during that enqueue. The request gets linked but not scheduled and stays pending until an unrelated wakeup or preemption on that CPU runs the deferred actions. The IMMED task sits behind the running task in the meantime. If nothing runs them before the scheduler is disabled, the request outlives the scheduler and points into its freed per-cpu area, which the next scheduler dereferences from run_deferred(). Test the core enqueue flags for the wakeup bit. Only the core's wakeup path is followed by task_woken_scx(). Fixes: 57ccf5ccdc56 ("sched_ext: Fix enqueue_task_scx() truncation of upper enqueue flags") Cc: stable@vger.kernel.org # v7.1+ Reported-by: Andrea Righi Link: https://lore.kernel.org/all/20260916145807.3250167-1-arighi@nvidia.com/ Signed-off-by: Tejun Heo Reviewed-by: Andrea Righi --- kernel/sched/ext/ext.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) (limited to 'kernel') diff --git a/kernel/sched/ext/ext.c b/kernel/sched/ext/ext.c index 725b890fcab9..e207ccd17164 100644 --- a/kernel/sched/ext/ext.c +++ b/kernel/sched/ext/ext.c @@ -2141,7 +2141,12 @@ static void enqueue_task_scx(struct rq *rq, struct task_struct *p, int core_enq_ int sticky_cpu = p->scx.sticky_cpu; u64 enq_flags = core_enq_flags | rq->scx.remote_activate_enq_flags; - if (enq_flags & ENQUEUE_WAKEUP) + /* + * SCX_RQ_IN_WAKEUP promises a task_woken_scx() call once this enqueue + * returns. Only the core's wakeup path delivers one. The flags stashed + * for a remote activation may carry the wakeup bit without it. + */ + if (core_enq_flags & ENQUEUE_WAKEUP) rq->scx.flags |= SCX_RQ_IN_WAKEUP; /* -- cgit v1.2.3 From cb86607ada73185f321baa7f9d94a08a3a40bbf5 Mon Sep 17 00:00:00 2001 From: fangqiurong Date: Thu, 17 Sep 2026 15:52:41 +0800 Subject: sched_ext: Don't run ops.dequeue() with a DSQ lock held ops.dequeue() is invoked with the source user DSQ's lock still held on the consume and move paths (scx_consume_dispatch_q(), move_task_between_dsqs()). A BPF scheduler which locks the source user DSQ from ops.dequeue() - e.g. by iterating it with bpf_iter_scx_dsq - self-deadlocks. ops.dequeue() can only call the "any" kfuncs and none of them can lock a builtin DSQ, so the global and bypass paths can't deadlock; however, all DSQ locks share one lockdep class, so iterating any user DSQ from ops.dequeue() on those paths trips the recursion check. Move the invocation after the DSQ unlock on all three paths. SCX_TASK_IN_CUSTODY is cleared under the lock serializing the transfer so that the callback is invoked exactly once. Fixes: ebf1ccff79c4 ("sched_ext: Fix ops.dequeue() semantics") Cc: stable@vger.kernel.org # v7.1+ Acked-by: Andrea Righi Signed-off-by: fangqiurong Signed-off-by: Tejun Heo --- kernel/sched/ext/ext.c | 44 ++++++++++++++++++++++---------------------- kernel/sched/ext/internal.h | 3 +-- kernel/sched/ext/sub.c | 10 +++++----- 3 files changed, 28 insertions(+), 29 deletions(-) (limited to 'kernel') diff --git a/kernel/sched/ext/ext.c b/kernel/sched/ext/ext.c index e207ccd17164..f568fd9973f6 100644 --- a/kernel/sched/ext/ext.c +++ b/kernel/sched/ext/ext.c @@ -1499,27 +1499,22 @@ static inline bool task_scx_migrating(struct task_struct *p) return p->scx.sticky_cpu >= 0; } -/* - * Call ops.dequeue() if the task is in BPF custody and not migrating. - * Clears %SCX_TASK_IN_CUSTODY when the callback is invoked. - */ -static void call_task_dequeue(struct scx_sched *sch, struct rq *rq, - struct task_struct *p, u64 deq_flags) +/* Must be called under the lock serializing @p's custody transfers. */ +static bool task_leave_custody(struct task_struct *p) { if (!(p->scx.flags & SCX_TASK_IN_CUSTODY) || task_scx_migrating(p)) - return; - - if (SCX_HAS_OP(sch, dequeue)) - SCX_CALL_OP_TASK(sch, dequeue, rq, p, deq_flags); + return false; p->scx.flags &= ~SCX_TASK_IN_CUSTODY; + return true; } static void rq_owned_post_enq(struct scx_sched *sch, struct rq *rq, struct scx_dispatch_q *dsq, struct task_struct *p, u64 enq_flags) { - call_task_dequeue(sch, rq, p, 0); + if (task_leave_custody(p) && SCX_HAS_OP(sch, dequeue)) + SCX_CALL_OP_TASK(sch, dequeue, rq, p, 0); /* * Only local inserts get the wakeup treatment below. Rejects kick the @@ -1705,20 +1700,28 @@ static void scx_dispatch_enqueue(struct scx_sched *sch, struct rq *rq, if (is_rq_owned) { rq_owned_post_enq(sch, rq, dsq, p, enq_flags); } else { + bool call_dequeue = false; + /* * Global and bypass DSQs are terminal - the task leaves the - * scheduler's custody, so ops.dequeue() fires here. It can run + * scheduler's custody, so ops.dequeue() fires. It can run * without @p's rq lock (finish_dispatch() passes the dispatch * rq); that's safe because dequeue_task_scx() waits on * SCX_OPSS_DISPATCHING (see the ops_state note above) and so * can't race it. A non-terminal DSQ keeps the task in custody. + * The custody transfer happens under @dsq->lock so that later + * consumers see the flag clear; the callback runs after + * @dsq->lock is dropped because it may lock a DSQ itself. */ if (dsq->id == SCX_DSQ_GLOBAL || dsq->id == SCX_DSQ_BYPASS) - call_task_dequeue(sch, rq, p, 0); + call_dequeue = task_leave_custody(p); else p->scx.flags |= SCX_TASK_IN_CUSTODY; raw_spin_unlock(&dsq->lock); + + if (call_dequeue && SCX_HAS_OP(sch, dequeue)) + SCX_CALL_OP_TASK(sch, dequeue, rq, p, 0); } /* @@ -2215,7 +2218,7 @@ retry: /* * A queued task must always be in BPF scheduler's custody. If * SCX_TASK_IN_CUSTODY is clear, finish_dispatch() on another - * CPU has already passed call_task_dequeue() (which clears the + * CPU has already passed task_leave_custody() (which clears the * flag), but has not yet written SCX_OPSS_NONE. That final * store does not require this rq's lock, so retrying with * cpu_relax() is bounded: we will observe NONE (or DISPATCHING, @@ -2263,7 +2266,8 @@ retry: * NONE but the task may still have %SCX_TASK_IN_CUSTODY set until * it is enqueued on the destination. */ - call_task_dequeue(sch, rq, p, deq_flags); + if (task_leave_custody(p) && SCX_HAS_OP(sch, dequeue)) + SCX_CALL_OP_TASK(sch, dequeue, rq, p, deq_flags); } static bool dequeue_task_scx(struct rq *rq, struct task_struct *p, int core_deq_flags) @@ -2379,14 +2383,10 @@ static void wakeup_preempt_scx(struct rq *rq, struct task_struct *p, int wake_fl } void scx_move_local_task_to_local_dsq(struct scx_sched *sch, struct task_struct *p, - u64 enq_flags, struct scx_dispatch_q *src_dsq, - struct rq *dst_rq) + u64 enq_flags, struct rq *dst_rq) { struct scx_dispatch_q *dst_dsq = scx_resolve_local_dsq(sch, dst_rq, p, &enq_flags); - /* @p is on @dst_rq, an rq-owned @src_dsq is covered by the rq lock */ - if (!dsq_is_rq_owned(src_dsq)) - lockdep_assert_held(&src_dsq->lock); lockdep_assert_rq_held(dst_rq); WARN_ON_ONCE(p->scx.holding_cpu >= 0); @@ -2634,8 +2634,8 @@ static struct rq *move_task_between_dsqs(struct scx_sched *sch, /* @p is going from a non-local DSQ to a local DSQ */ if (src_rq == dst_rq) { scx_task_unlink_from_dsq(p, src_dsq); - scx_move_local_task_to_local_dsq(sch, p, enq_flags, src_dsq, dst_rq); raw_spin_unlock(&src_dsq->lock); + scx_move_local_task_to_local_dsq(sch, p, enq_flags, dst_rq); } else { raw_spin_unlock(&src_dsq->lock); move_remote_task_to_local_dsq(sch, p, enq_flags, src_rq, dst_rq); @@ -2685,8 +2685,8 @@ retry: if (rq == task_rq) { scx_task_unlink_from_dsq(p, dsq); - scx_move_local_task_to_local_dsq(sch, p, enq_flags, dsq, rq); raw_spin_unlock(&dsq->lock); + scx_move_local_task_to_local_dsq(sch, p, enq_flags, rq); return true; } diff --git a/kernel/sched/ext/internal.h b/kernel/sched/ext/internal.h index 115c96fbf932..d150de10a5c9 100644 --- a/kernel/sched/ext/internal.h +++ b/kernel/sched/ext/internal.h @@ -2065,8 +2065,7 @@ void scx_dispatch_dequeue(struct rq *rq, struct task_struct *p); void scx_do_enqueue_task(struct rq *rq, struct task_struct *p, u64 enq_flags, int sticky_cpu); void scx_move_local_task_to_local_dsq(struct scx_sched *sch, struct task_struct *p, - u64 enq_flags, struct scx_dispatch_q *src_dsq, - struct rq *dst_rq); + u64 enq_flags, struct rq *dst_rq); bool scx_consume_dispatch_q(struct scx_sched *sch, struct rq *rq, struct scx_dispatch_q *dsq, u64 enq_flags); bool scx_consume_global_dsq(struct scx_sched *sch, struct rq *rq); diff --git a/kernel/sched/ext/sub.c b/kernel/sched/ext/sub.c index a30c965b175d..3036190b0662 100644 --- a/kernel/sched/ext/sub.c +++ b/kernel/sched/ext/sub.c @@ -555,8 +555,8 @@ static void scx_rescue_timerfn(struct timer_list *timer) scx.dsq_list.node); scx_task_unlink_from_dsq(p, &rq->scx.rescue.dsq); scx_rescue_admit(rq, p, slice); - scx_move_local_task_to_local_dsq(scx_task_sched(p), p, SCX_ENQ_IGNORE_CAPS, - &rq->scx.rescue.dsq, rq); + scx_move_local_task_to_local_dsq(scx_task_sched(p), p, + SCX_ENQ_IGNORE_CAPS, rq); if (sched_class_above(&ext_sched_class, rq->curr->sched_class)) resched_curr(rq); } else if (p->scx.dsq && rq->scx.rescue.budget > 2 * scx_rescue_quantum_ns) { @@ -572,7 +572,7 @@ static void scx_rescue_timerfn(struct timer_list *timer) scx_task_unlink_from_dsq(p, &rq->scx.local_dsq); scx_move_local_task_to_local_dsq(scx_task_sched(p), p, SCX_ENQ_HEAD | SCX_ENQ_PREEMPT | SCX_ENQ_IGNORE_CAPS, - &rq->scx.local_dsq, rq); + rq); } out_arm: scx_rescue_timer_arm(rq); @@ -596,8 +596,8 @@ void scx_rescue_flush(struct rq *rq) /* and flush out all pending ones */ list_for_each_entry_safe(p, n, &rq->scx.rescue.dsq.list, scx.dsq_list.node) { scx_task_unlink_from_dsq(p, &rq->scx.rescue.dsq); - scx_move_local_task_to_local_dsq(scx_task_sched(p), p, SCX_ENQ_IGNORE_CAPS, - &rq->scx.rescue.dsq, rq); + scx_move_local_task_to_local_dsq(scx_task_sched(p), p, + SCX_ENQ_IGNORE_CAPS, rq); } timer_delete(&rq->scx.rescue.timer); -- cgit v1.2.3 From 40c2096961b4e8f48d1fc17406a90c5a36ac0a8d Mon Sep 17 00:00:00 2001 From: Kumar Kartikeya Dwivedi Date: Mon, 14 Sep 2026 15:19:20 +0200 Subject: bpf: Verify global subprogs in each sleepability context Global subprograms are verified independently with a fresh verifier root. do_check_common() currently seeds that root's in_sleepable state from the program, even though a global subprogram can also run from callbacks whose execution context differs from the program's main entry point. In particular, workqueue and task-work callbacks are sleepable even when the containing program is not. A global subprogram of that program is therefore verified as non-sleepable, making in_rcu_cs() true and allowing loads of RCU-protected kptrs to produce trusted MEM_RCU pointers. The same subprogram can then be called from a sleepable callback without a classic RCU reader. It can retain such a pointer while the object is freed and use it after free. The verifier's execution-context predicates are complementary. A state is sleepable only when in_sleepable is set and no RCU, preemption, IRQ, or lock region is active. Each condition which prevents sleeping also provides RCU protection, while in_rcu_cs() treats a non-sleepable state as implicitly protected. Use this relationship to represent a global subprogram caller with only the result of in_sleepable_context(). A protected sleepable caller is normalized to in_sleepable=false at the independent verification root. This both prevents sleepable operations and makes in_rcu_cs() true without copying caller-owned lock state. Track only the contexts in which each global subprogram is actually reached. Verify it once if all reachable calls use the same context, and twice only if both sleepable and non-sleepable calls reach it. Calls found while verifying globals or asynchronous callbacks mark further contexts for checking. Repeat the existing subprogram walk until all called contexts have been verified; unreachable global calls remain unchecked. Accumulate instruction counts over those verification passes. Preserve the total recorded before each pass, since path accounting has already added this pass's synchronous instructions and its root total must also include asynchronous subprograms. This makes an unprotected callback verify the global subprogram as sleepable, turning its RCU-protected kptr load into an untrusted pointer. Protected callers and global subprograms which do not depend on implicit RCU protection remain valid. Fixes: 81f1d7a583fa ("bpf: wq: add bpf_wq_set_callback_impl") Fixes: 38aa7003e369 ("bpf: task work scheduling kfuncs") Reported-by: Nicholas Carlini Suggested-by: Nicholas Carlini Signed-off-by: Kumar Kartikeya Dwivedi Acked-by: Eduard Zingerman Link: https://patch.msgid.link/20260914131923.2544250-2-memxor@gmail.com Signed-off-by: Eduard Zingerman --- kernel/bpf/verifier.c | 71 +++++++++++++++++++++++++++------------------------ 1 file changed, 37 insertions(+), 34 deletions(-) (limited to 'kernel') diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index ddba53eaa333..5d7080c260d8 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -9931,6 +9931,7 @@ static int check_func_call(struct bpf_verifier_env *env, struct bpf_insn *insn, if (err == -EFAULT) return err; if (bpf_subprog_is_global(env, subprog)) { + struct bpf_func_info_aux *sub_aux = subprog_aux(env, subprog); const char *sub_name = bpf_subprog_name(env, subprog); const char *operation; bool returns_void; @@ -9962,11 +9963,10 @@ static int check_func_call(struct bpf_verifier_env *env, struct bpf_insn *insn, if (env->log.level & BPF_LOG_LEVEL) verbose(env, "Func#%d ('%s') is global and assumed valid.\n", subprog, sub_name); + sub_aux->called[in_sleepable_context(env)] = true; returns_void = subprog_returns_void(env, subprog); if (env->subprog_info[subprog].changes_pkt_data) clear_all_pkt_pointers(env); - /* mark global subprog for verifying after main prog */ - subprog_aux(env, subprog)->called = true; if (returns_void) bpf_diag_record_scrub(env, &caller->regs[BPF_REG_0], BPF_DIAG_MOD_CALLER_SAVED); else @@ -10784,11 +10784,7 @@ int bpf_get_helper_proto(struct bpf_verifier_env *env, int func_id, /* Check if we're in a sleepable context. */ static inline bool in_sleepable_context(struct bpf_verifier_env *env) { - return !env->cur_state->active_rcu_locks && - !env->cur_state->active_preempt_locks && - !env->cur_state->active_locks && - !env->cur_state->active_irq_id && - in_sleepable(env); + return !in_rcu_cs(env); } static const char *non_sleepable_context_description(struct bpf_verifier_env *env) @@ -19447,13 +19443,14 @@ static void free_states(struct bpf_verifier_env *env) } } -static int do_check_common(struct bpf_verifier_env *env, int subprog) +static int do_check_common(struct bpf_verifier_env *env, int subprog, bool is_sleepable) { bool pop_log = !(env->log.level & BPF_LOG_LEVEL2); struct bpf_subprog_info *sub = subprog_info(env, subprog); struct bpf_prog_aux *aux = env->prog->aux; struct bpf_verifier_state *state; struct bpf_reg_state *regs; + u32 old_insns_total = sub->insns_total; u32 insn_processed = env->insn_processed; int ret, i; @@ -19466,7 +19463,7 @@ static int do_check_common(struct bpf_verifier_env *env, int subprog) state->curframe = 0; state->speculative = false; state->branches = 1; - state->in_sleepable = env->prog->sleepable; + state->in_sleepable = is_sleepable; state->frame[0] = kzalloc_obj(struct bpf_func_state, GFP_KERNEL_ACCOUNT); if (!state->frame[0]) { kfree(state); @@ -19607,8 +19604,10 @@ out: * not accounted as callees by account_current_path(). * Accumulate their total counts as total counts of the main or * global subprog hosting the async call. + * Start from the saved total of earlier contexts: adding to the current + * total would count this pass's synchronous paths twice. */ - env->subprog_info[subprog].insns_total = env->insn_processed - insn_processed; + sub->insns_total = old_insns_total + (env->insn_processed - insn_processed); return ret; } @@ -19636,14 +19635,19 @@ static int do_check_subprogs(struct bpf_verifier_env *env) { struct bpf_prog_aux *aux = env->prog->aux; struct bpf_func_info_aux *sub_aux; - int i, ret, new_cnt; + int context, i, ret, new_cnt; if (!aux->func_info) return 0; - /* exception callback is presumed to be always called */ - if (env->exception_callback_subprog) - subprog_aux(env, env->exception_callback_subprog)->called = true; + /* + * Callbacks cannot throw, so the exception callback always runs in the + * main program's context. It is presumed to be always called. + */ + if (env->exception_callback_subprog) { + sub_aux = subprog_aux(env, env->exception_callback_subprog); + sub_aux->called[env->prog->sleepable] = true; + } again: new_cnt = 0; @@ -19652,29 +19656,28 @@ again: continue; sub_aux = subprog_aux(env, i); - if (!sub_aux->called || sub_aux->verified) - continue; + for (context = 0; context < ARRAY_SIZE(sub_aux->called); context++) { + if (!sub_aux->called[context] || sub_aux->verified[context]) + continue; - env->insn_idx = env->subprog_info[i].start; - WARN_ON_ONCE(env->insn_idx == 0); - ret = do_check_common(env, i); - if (ret) { - return ret; - } else if (env->log.level & BPF_LOG_LEVEL) { - verbose(env, "Func#%d ('%s') is safe for any args that match its prototype\n", - i, bpf_subprog_name(env, i)); - } + env->insn_idx = env->subprog_info[i].start; + WARN_ON_ONCE(env->insn_idx == 0); + ret = do_check_common(env, i, context); + if (ret) + return ret; + if (env->log.level & BPF_LOG_LEVEL) + verbose(env, "Func#%d ('%s') is safe for any args " + "that match its prototype\n", + i, bpf_subprog_name(env, i)); - /* We verified new global subprog, it might have called some - * more global subprogs that we haven't verified yet, so we - * need to do another pass over subprogs to verify those. - */ - sub_aux->verified = true; - new_cnt++; + sub_aux->verified[context] = true; + new_cnt++; + } } - /* We can't loop forever as we verify at least one global subprog on - * each pass. + /* + * We can't loop forever as each pass verifies at least one new context, + * and there are only two contexts per global subprog. */ if (new_cnt) goto again; @@ -19687,7 +19690,7 @@ static int do_check_main(struct bpf_verifier_env *env) int ret; env->insn_idx = 0; - ret = do_check_common(env, 0); + ret = do_check_common(env, 0, env->prog->sleepable); if (!ret) env->prog->aux->stack_depth = env->subprog_info[0].stack_depth; return ret; -- cgit v1.2.3 From 50e80e2bb5e2be8515205b9c496b9640ddefa434 Mon Sep 17 00:00:00 2001 From: Weiming Shi Date: Tue, 15 Sep 2026 01:02:07 +0800 Subject: bpf: Skip unsettled links in link iterator bpf_link_prime() inserts a link into link_idr before anon_inode_getfile() succeeds and before bpf_link_settle() publishes the ID in link->id. bpf_link_by_id() treats such an ID-zero link as unsettled, but the link iterator takes a reference without this check. If anon_inode_getfile() then fails, the creator removes the ID and frees its still-private link directly. The iterator is left with a dangling reference and its next bpf_link_put() accesses freed memory. Treat ID-zero entries as transient in bpf_link_get_curr_or_next(), just as bpf_link_by_id() does. BUG: KASAN: slab-use-after-free in bpf_link_put Write of size 8 by task exp/384 Call Trace: bpf_link_put kernel/bpf/syscall.c:3372 bpf_link_seq_next kernel/bpf/link_iter.c:33 bpf_seq_read kernel/bpf/bpf_iter.c:158 vfs_read fs/read_write.c:572 ksys_read fs/read_write.c:716 do_syscall_64 arch/x86/entry/syscall_64.c:84 entry_SYSCALL_64_after_hwframe arch/x86/entry/entry_64.S:121 Kernel panic - not syncing: KASAN: panic_on_warn set ... Fixes: 9f8836127308 ("bpf: Add bpf_link iterator") Reported-by: Xiang Mei Signed-off-by: Weiming Shi Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20260914170206.170723-2-bestswngs@gmail.com --- kernel/bpf/syscall.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) (limited to 'kernel') diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index 853b47f81384..244a939b9d2d 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -6042,7 +6042,10 @@ struct bpf_link *bpf_link_get_curr_or_next(u32 *id) again: link = idr_get_next(&link_idr, id); if (link) { - link = bpf_link_inc_not_zero(link); + if (link->id) + link = bpf_link_inc_not_zero(link); + else + link = ERR_PTR(-EAGAIN); if (IS_ERR(link)) { (*id)++; goto again; -- cgit v1.2.3 From 1d653a183973f5283a3db5a38cd5e195eb152244 Mon Sep 17 00:00:00 2001 From: David Carlier Date: Thu, 17 Sep 2026 22:24:07 +0100 Subject: fprobe: Terminate the fgraph_data list when the reservation is not filled fprobe_fgraph_entry() reserves shadow stack space for every fprobe with an exit handler, but only fills it for those whose entry handler returns 0. fgraph_reserve_data() does not clear the area, so fprobe_return() parses the unused tail as headers left over from an earlier call, and an exit handler can run twice or despite its entry handler asking to skip it. Write a zero word after the last entry to terminate the walk. A zeroed slot does not decode to a NULL fprobe on the arches that encode the header into one unsigned long, since arch_decode_fprobe_header_fp() ORs in FPROBE_HEADER_MSB_PATTERN, so make read_fprobe_header() return NULL for a zeroed slot. Link: https://lore.kernel.org/all/20260917212407.384468-1-devnexen@gmail.com/ Fixes: e0a384434ae1 ("tracing: fprobe: do not zero out unused fgraph_data") Cc: stable@vger.kernel.org Suggested-by: Masami Hiramatsu (Google) Signed-off-by: David Carlier Signed-off-by: Masami Hiramatsu (Google) --- kernel/trace/fprobe.c | 15 +++++++++++++++ 1 file changed, 15 insertions(+) (limited to 'kernel') diff --git a/kernel/trace/fprobe.c b/kernel/trace/fprobe.c index 1e9b00997ff2..9f2d98181779 100644 --- a/kernel/trace/fprobe.c +++ b/kernel/trace/fprobe.c @@ -171,6 +171,11 @@ static inline bool write_fprobe_header(unsigned long *stack, static inline void read_fprobe_header(unsigned long *stack, struct fprobe **fp, unsigned int *size_words) { + if (!*stack) { + *fp = NULL; + *size_words = 0; + return; + } *fp = arch_decode_fprobe_header_fp(*stack); *size_words = arch_decode_fprobe_header_size(*stack); } @@ -203,6 +208,12 @@ static inline void read_fprobe_header(unsigned long *stack, { struct __fprobe_header *fph = (struct __fprobe_header *)stack; + if (!*stack) { + *fp = NULL; + *size_words = 0; + return; + } + *fp = fph->fp; *size_words = fph->size_words; } @@ -635,6 +646,10 @@ static int fprobe_fgraph_entry(struct ftrace_graph_ent *trace, struct fgraph_ops } } + /* Terminate the list, fgraph_reserve_data() does not clear it. */ + if (used && used < reserved_words) + fgraph_data[used] = 0; + /* If any exit_handler is set, data must be used. */ return used != 0; } -- cgit v1.2.3 From 261b61d3735b042ae25634f795c4540be0fc140c Mon Sep 17 00:00:00 2001 From: Kumar Kartikeya Dwivedi Date: Fri, 18 Sep 2026 01:32:09 +0200 Subject: bpf: Make post-verification instruction rewrites killable After do_check() returns, the verifier runs several instruction rewrite passes. Some of them patch or remove one instruction at a time. Each operation moves the remaining instruction and auxiliary-data arrays and adjusts all branch offsets, making the overall work quadratic in the program length. A privileged loader can submit 131072 unconditional jumps by zero followed by a valid return. Verification finishes quickly, but bpf_opt_remove_nops() then spends a long time removing each jump separately. Since this post-verification work neither checks for signals nor reschedules, a pending SIGKILL cannot terminate the task until the rewrite finishes. Make bpf_patch_insn_data() and verifier_remove_insns() common cancellation and rescheduling points. These helpers run from BPF_PROG_LOAD process context, and bpf_patch_insn_data() can already sleep while reallocating auxiliary data. Report interrupted constant blinding as -EINTR and propagate it through both JIT paths, including kernels that permit interpreter fallback. Other blinding failures retain the existing fallback behavior. This does not reduce the quadratic cost of the rewrite passes, but it makes the work preemptible and allows a killed loader to be torn down promptly. Fixes: 52875a04f4b2 ("bpf: verifier: remove dead code") Reported-by: Nicholas Carlini Suggested-by: Nicholas Carlini Signed-off-by: Kumar Kartikeya Dwivedi Acked-by: Eduard Zingerman Link: https://patch.msgid.link/20260917233222.2542500-2-memxor@gmail.com Signed-off-by: Eduard Zingerman --- kernel/bpf/core.c | 21 +++++++++++++++++---- kernel/bpf/fixups.c | 24 ++++++++++++++++++++++-- 2 files changed, 39 insertions(+), 6 deletions(-) (limited to 'kernel') diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c index 8b294dfc1ad4..2e3bf8113ae9 100644 --- a/kernel/bpf/core.c +++ b/kernel/bpf/core.c @@ -19,6 +19,7 @@ #include #include +#include #include #include #include @@ -1619,6 +1620,8 @@ struct bpf_prog *bpf_jit_blind_constants(struct bpf_verifier_env *env, struct bp * fix it up here on error. */ bpf_jit_prog_release_other(prog, clone); + if (env && fatal_signal_pending(current)) + return ERR_PTR(-EINTR); return IS_ERR(tmp) ? tmp : ERR_PTR(-ENOMEM); } @@ -2636,11 +2639,14 @@ static struct bpf_prog *bpf_prog_jit_compile(struct bpf_verifier_env *env, struc orig_prog = prog; prog = bpf_jit_blind_constants(env, prog); /* - * If blinding was requested and we failed during blinding, we must fall - * back to the interpreter. + * Fall back to the interpreter after blinding failures, except when + * the loader was killed. */ - if (IS_ERR(prog)) + if (IS_ERR(prog)) { + if (PTR_ERR(prog) == -EINTR) + return prog; goto out_restore; + } prog = bpf_int_jit_compile(env, prog); if (prog->jited) { @@ -2659,6 +2665,8 @@ out_restore: struct bpf_prog *__bpf_prog_select_runtime(struct bpf_verifier_env *env, struct bpf_prog *fp, int *err) { + struct bpf_prog *jit_prog; + /* In case of BPF to BPF calls, verifier did all the prep * work with regards to JITing, etc. */ @@ -2681,7 +2689,12 @@ struct bpf_prog *__bpf_prog_select_runtime(struct bpf_verifier_env *env, struct if (*err) return fp; - fp = bpf_prog_jit_compile(env, fp); + jit_prog = bpf_prog_jit_compile(env, fp); + if (IS_ERR(jit_prog)) { + *err = PTR_ERR(jit_prog); + return fp; + } + fp = jit_prog; bpf_prog_jit_attempt_done(fp); if (!fp->jited && jit_needed) { *err = -ENOTSUPP; diff --git a/kernel/bpf/fixups.c b/kernel/bpf/fixups.c index 52d3cec33672..d6f83521fc78 100644 --- a/kernel/bpf/fixups.c +++ b/kernel/bpf/fixups.c @@ -8,6 +8,7 @@ #include #include #include +#include #include #include "disasm.h" @@ -306,12 +307,28 @@ static void adjust_poke_descs(struct bpf_prog *prog, u32 off, u32 len) } } +/* + * Some post-verification instruction rewriting passes require an + * O(prog->len) operation per instruction. Keep their shared primitives + * killable and preemptible. + */ +static bool bpf_rewrite_must_abort(void) +{ + if (fatal_signal_pending(current)) + return true; + cond_resched(); + return false; +} + struct bpf_prog *bpf_patch_insn_data(struct bpf_verifier_env *env, u32 off, const struct bpf_insn *patch, u32 len) { struct bpf_prog *new_prog; struct bpf_insn_aux_data *new_data = NULL; + if (bpf_rewrite_must_abort()) + return NULL; + if (len > 1) { new_data = vrealloc(env->insn_aux_data, array_size(env->prog->len + len - 1, @@ -523,6 +540,9 @@ static int verifier_remove_insns(struct bpf_verifier_env *env, u32 off, u32 cnt) unsigned int orig_prog_len = env->prog->len; int err; + if (bpf_rewrite_must_abort()) + return -EINTR; + if (bpf_prog_is_offloaded(env->prog->aux)) bpf_prog_offload_remove_insns(env, off, cnt); @@ -1356,7 +1376,7 @@ int bpf_jit_subprogs(struct bpf_verifier_env *env) } prog = bpf_jit_blind_constants(env, prog); if (IS_ERR(prog)) { - err = -ENOMEM; + err = PTR_ERR(prog); prog = orig_prog; goto out_restore; } @@ -1433,7 +1453,7 @@ int bpf_fixup_call_args(struct bpf_verifier_env *env) err = bpf_jit_subprogs(env); if (err == 0) return 0; - if (err == -EFAULT) + if (err == -EFAULT || err == -EINTR) return err; } #ifndef CONFIG_BPF_JIT_ALWAYS_ON -- cgit v1.2.3 From fd16449a9b3b31a8f18944c2f0e29e4e218ca2cf Mon Sep 17 00:00:00 2001 From: Kumar Kartikeya Dwivedi Date: Fri, 18 Sep 2026 01:32:10 +0200 Subject: bpf: Preserve packet pointer class displacement in regsafe() regsafe() maps packet pointer IDs between states and checks that each current register range is a subset of the corresponding explored register range. It does not, however, preserve the displacement between registers that share a packet pointer ID. This is unsound because packet range is shared by ID. A bounds check on one class member updates every member, and a later access can consume the range through another member. Commit 022ac0750883 ("bpf: use reg->var_off instead of reg->off for pointers") folded the fixed pointer offset into r64 and removed the old off equality check, so two individually narrower registers can prune even when their displacement has changed. The explored path can then license an out-of-bounds packet access on the pruned path. Require matching range bases for packet pointers with an ID. Together with the existing ID mapping, this preserves the displacement between members of each packet-pointer class without adding per-ID state. Packet pointers without an ID remain unaffected. Fixes: 022ac0750883 ("bpf: use reg->var_off instead of reg->off for pointers") Reported-by: Nicholas Carlini Suggested-by: Nicholas Carlini Signed-off-by: Kumar Kartikeya Dwivedi Acked-by: Eduard Zingerman Link: https://patch.msgid.link/20260917233222.2542500-3-memxor@gmail.com Signed-off-by: Eduard Zingerman --- kernel/bpf/states.c | 3 +++ 1 file changed, 3 insertions(+) (limited to 'kernel') diff --git a/kernel/bpf/states.c b/kernel/bpf/states.c index 66fb11b6c6a7..6c88ad95b63b 100644 --- a/kernel/bpf/states.c +++ b/kernel/bpf/states.c @@ -635,6 +635,9 @@ static bool regsafe(struct bpf_verifier_env *env, struct bpf_reg_state *rold, /* id relations must be preserved */ if (!check_ids(rold->id, rcur->id, idmap)) return false; + /* Preserve displacements between pointers sharing an ID. */ + if (rold->id && rold->r64.base != rcur->r64.base) + return false; /* new val must satisfy old val knowledge */ return range_within(rold, rcur) && tnum_in(rold->var_off, rcur->var_off); -- cgit v1.2.3 From c26e97721b172163042b98572fead234797f2c3c Mon Sep 17 00:00:00 2001 From: Kumar Kartikeya Dwivedi Date: Fri, 18 Sep 2026 01:32:12 +0200 Subject: bpf: Apply CO-RE relocations before subprogram validation check_subprogs() verifies that each subprogram ends in an exit or an unconditional jump before in-kernel CO-RE relocations are applied. An unresolved relocation can then replace that terminal instruction with an invalid helper call. The resulting fall-through into another subprogram breaks the CFG invariant used by postorder and stack liveness analysis, which can write past their per-subprogram arrays. Apply CO-RE relocations immediately after preparing the program BTF, before subprogram discovery and validation. Keep func_info and line_info validation after subprogram discovery because those records depend on the complete subprogram layout. Reject an ldimm64 first slot at the end of the instruction stream before CO-RE can inspect its missing second slot. check_subprogs() previously rejected this form before relocation processing because it is not a valid subprogram terminator. Moving CO-RE ahead of check_subprogs() removes that implicit protection, so perform an explicit check before applying relocations. Include core_relo_cnt when deciding whether to prepare program BTF. A load that supplied only CO-RE relocation metadata previously skipped both BTF setup and relocation processing. Fixes: fbd94c7afcf9 ("bpf: Pass a set of bpf_core_relo-s to prog_load command.") Suggested-by: Andrii Nakryiko Suggested-by: Alexei Starovoitov Suggested-by: Eduard Zingerman Signed-off-by: Kumar Kartikeya Dwivedi Acked-by: Eduard Zingerman Link: https://patch.msgid.link/20260917233222.2542500-5-memxor@gmail.com Signed-off-by: Eduard Zingerman --- kernel/bpf/check_btf.c | 12 ++++-------- kernel/bpf/verifier.c | 12 +++++++++++- 2 files changed, 15 insertions(+), 9 deletions(-) (limited to 'kernel') diff --git a/kernel/bpf/check_btf.c b/kernel/bpf/check_btf.c index 0e8b3ccc7a5b..4c1ed842f661 100644 --- a/kernel/bpf/check_btf.c +++ b/kernel/bpf/check_btf.c @@ -338,9 +338,9 @@ err_free: #define MIN_CORE_RELO_SIZE sizeof(struct bpf_core_relo) #define MAX_CORE_RELO_SIZE MAX_FUNCINFO_REC_SIZE -static int check_core_relo(struct bpf_verifier_env *env, - const union bpf_attr *attr, - bpfptr_t uattr) +int bpf_check_core_relo(struct bpf_verifier_env *env, + const union bpf_attr *attr, + bpfptr_t uattr) { u32 i, nr_core_relo, ncopy, expected_size, rec_size; struct bpf_core_relo core_relo = {}; @@ -414,7 +414,7 @@ int bpf_prepare_btf_info(struct bpf_verifier_env *env, struct btf *btf; int err; - if (!attr->func_info_cnt && !attr->line_info_cnt) { + if (!attr->func_info_cnt && !attr->line_info_cnt && !attr->core_relo_cnt) { if (check_abnormal_return(env)) return -EINVAL; return 0; @@ -455,9 +455,5 @@ int bpf_check_btf_info(struct bpf_verifier_env *env, if (err) return err; - err = check_core_relo(env, attr, uattr); - if (err) - return err; - return 0; } diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 5d7080c260d8..33161dc64568 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -21199,6 +21199,11 @@ int bpf_check(struct bpf_prog **prog, union bpf_attr *attr, bpfptr_t uattr, ret = bpf_diag_init(env); if (ret) goto err_prep; + if (env->prog->insnsi[env->prog->len - 1].code == (BPF_LD | BPF_IMM | BPF_DW)) { + verbose(env, "invalid bpf_ld_imm64 insn\n"); + ret = -EINVAL; + goto err_prep; + } if (env->signature) { ret = bpf_prog_calc_tag(env->prog); if (ret < 0) @@ -21274,6 +21279,11 @@ int bpf_check(struct bpf_prog **prog, union bpf_attr *attr, bpfptr_t uattr, if (ret < 0) goto skip_full_check; + /* Apply CO-RE before validating the program's instruction layout. */ + ret = bpf_check_core_relo(env, attr, uattr); + if (ret < 0) + goto skip_full_check; + /* Discover all subprograms before validating their layout and BTF. */ ret = add_subprogs(env); if (ret < 0) @@ -21283,7 +21293,7 @@ int bpf_check(struct bpf_prog **prog, union bpf_attr *attr, bpfptr_t uattr, if (ret < 0) goto skip_full_check; - /* Validate BTF against the complete subprogram layout and apply CO-RE. */ + /* Validate BTF against the complete subprogram layout. */ ret = bpf_check_btf_info(env, attr, uattr); if (ret < 0) goto skip_full_check; -- cgit v1.2.3 From 71919742c83c32afcccf06a7a28e28f3f55f21a2 Mon Sep 17 00:00:00 2001 From: Kumar Kartikeya Dwivedi Date: Fri, 18 Sep 2026 01:32:16 +0200 Subject: bpf: Assign lock identity to callback map values A nested bpf_for_each_map_elem() callback can unlock a different element of the same map: static long inner(void *map, int *key, struct value *v, struct value **outer_value) { bpf_spin_lock(&v->lock); bpf_spin_unlock(&(*outer_value)->lock); return 0; } static long outer(void *map, int *key, struct value *v, void *ctx) { bpf_for_each_map_elem(map, inner, &v, 0); return 0; } Both callback values currently have ID zero and the same map_ptr. process_spin_lock() compares those two fields, so it accepts the unlock even though the two callbacks can receive different map elements. Assign a fresh ID to every callback map value in the for-each, timer/workqueue, and task-work constructors. Copies of one callback argument retain its ID, so locking and unlocking through that argument continues to work. Distinct callbacks also get distinct IDs for single-element arrays, including inner arrays sharing inner_map_meta. Preserve map_uid for every inner-map lookup and compare it through check_ids() during state pruning. This preserves relationships between maps, keys, and values while allowing equivalent states with different lookup IDs to match. It avoids field-specific rules for when an inner map needs an identity. Move map_uid out of the metadata union and next to the other IDs, so register comparisons can use the existing memcmp() ranges and remap the IDs separately. Clear it when resetting a register or converting a map lookup result to a socket pointer. Shrink frameno to u8, which is enough for MAX_CALL_FRAMES, to make room without growing bpf_reg_state. Fixes: d0d78c1df9b1 ("bpf: Allow locking bpf_spin_lock global variables") Reported-by: Nicholas Carlini Suggested-by: Nicholas Carlini Signed-off-by: Kumar Kartikeya Dwivedi Acked-by: Eduard Zingerman Link: https://patch.msgid.link/20260917233222.2542500-9-memxor@gmail.com Signed-off-by: Eduard Zingerman --- kernel/bpf/states.c | 6 ++++-- kernel/bpf/verifier.c | 13 +++++++++---- 2 files changed, 13 insertions(+), 6 deletions(-) (limited to 'kernel') diff --git a/kernel/bpf/states.c b/kernel/bpf/states.c index 6c88ad95b63b..e4ec007f7fa6 100644 --- a/kernel/bpf/states.c +++ b/kernel/bpf/states.c @@ -491,7 +491,8 @@ static bool regs_exact(const struct bpf_reg_state *rold, { return memcmp(rold, rcur, offsetof(struct bpf_reg_state, id)) == 0 && check_ids(rold->id, rcur->id, idmap) && - check_ids(rold->parent_id, rcur->parent_id, idmap); + check_ids(rold->parent_id, rcur->parent_id, idmap) && + check_ids(rold->map_uid, rcur->map_uid, idmap); } enum exact_level { @@ -616,7 +617,8 @@ static bool regsafe(struct bpf_verifier_env *env, struct bpf_reg_state *rold, range_within(rold, rcur) && tnum_in(rold->var_off, rcur->var_off) && check_ids(rold->id, rcur->id, idmap) && - check_ids(rold->parent_id, rcur->parent_id, idmap); + check_ids(rold->parent_id, rcur->parent_id, idmap) && + check_ids(rold->map_uid, rcur->map_uid, idmap); case PTR_TO_PACKET_META: case PTR_TO_PACKET: /* We must have at least as much range as the old ptr diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 33161dc64568..02be326f235c 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -1864,6 +1864,7 @@ static void __mark_reg_known(struct bpf_reg_state *reg, u64 imm) offsetof(struct bpf_reg_state, var_off) - sizeof(reg->type)); reg->id = 0; reg->parent_id = 0; + reg->map_uid = 0; ___mark_reg_known(reg, imm); } @@ -1925,17 +1926,18 @@ static void refine_map_lookup_value(struct bpf_reg_state *reg) if (map->inner_map_meta) { reg->type = CONST_PTR_TO_MAP | maybe_null; reg->map_ptr = map->inner_map_meta; - /* transfer reg's id which is unique for every map_lookup_elem + /* + * transfer reg's id which is unique for every map_lookup_elem * as UID of the inner map. */ - if (btf_record_has_field(map->inner_map_meta->record, - BPF_TIMER | BPF_WORKQUEUE | BPF_TASK_WORK)) - reg->map_uid = reg->id; + reg->map_uid = reg->id; } else if (map->map_type == BPF_MAP_TYPE_XSKMAP) { reg->type = PTR_TO_XDP_SOCK | maybe_null; + reg->map_uid = 0; } else if (map->map_type == BPF_MAP_TYPE_SOCKMAP || map->map_type == BPF_MAP_TYPE_SOCKHASH) { reg->type = PTR_TO_SOCKET | maybe_null; + reg->map_uid = 0; } } @@ -10048,6 +10050,7 @@ int map_set_for_each_callback_args(struct bpf_verifier_env *env, __mark_reg_known_zero(&callee->regs[BPF_REG_3]); callee->regs[BPF_REG_3].map_ptr = caller->regs[BPF_REG_1].map_ptr; callee->regs[BPF_REG_3].map_uid = caller->regs[BPF_REG_1].map_uid; + callee->regs[BPF_REG_3].id = ++env->id_gen; /* pointer to stack or null */ callee->regs[BPF_REG_4] = caller->regs[BPF_REG_3]; @@ -10144,6 +10147,7 @@ static int set_timer_callback_state(struct bpf_verifier_env *env, __mark_reg_known_zero(&callee->regs[BPF_REG_3]); callee->regs[BPF_REG_3].map_ptr = map_ptr; callee->regs[BPF_REG_3].map_uid = map_uid; + callee->regs[BPF_REG_3].id = ++env->id_gen; /* unused */ bpf_mark_reg_not_init(env, &callee->regs[BPF_REG_4]); @@ -10262,6 +10266,7 @@ static int set_task_work_schedule_callback_state(struct bpf_verifier_env *env, __mark_reg_known_zero(&callee->regs[BPF_REG_3]); callee->regs[BPF_REG_3].map_ptr = map_ptr; callee->regs[BPF_REG_3].map_uid = map_uid; + callee->regs[BPF_REG_3].id = ++env->id_gen; /* unused */ bpf_mark_reg_not_init(env, &callee->regs[BPF_REG_4]); -- cgit v1.2.3 From 88aed0422f39b22406f35f1e758cea25e7bbcfb5 Mon Sep 17 00:00:00 2001 From: Vinay Belgaumkar Date: Fri, 4 Sep 2026 11:16:24 -0700 Subject: perf: Fix null pointer access in is_include_guest_event() A typical module unload occurring event when there is an active perf connection leads to freeing of the pmu pointer. The call log is something like: .. __pmu_detach_event pmu_detach_event pmu_detach_events perf_pmu_unregister .. __pmu_detach_event() sets event->pmu to null. When the perf connection finally is closed, the following stack trace is observed: Oops: general protection fault, kernel NULL pointer dereference ... RIP: 0010:_free_event+0x3e/0x370 ... Call Trace: ... perf_event_release_kernel+0x260/0x2d0 perf_release+0x12/0x20 A call to mediated_pmu_unaccount_event() inside _free_event() is the root cause of this crash. Adding a check inside is_include_guest_event() ensures we don't accidentally access a null pmu ptr. In addition to this, we will now call mediated_pmu_unaccount_event() before clearing the pmu ptr so that nr_include_guest_events counts are maintained correctly. Fixes: eff95e170275 ("perf: Add APIs to create/release mediated guest vPMUs") Assisted-by: Claude:Claude-Sonnet-5 Signed-off-by: Vinay Belgaumkar Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Dapeng Mi Link: https://patch.msgid.link/20260904181625.1394082-1-vinay.belgaumkar@intel.com --- kernel/events/core.c | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'kernel') diff --git a/kernel/events/core.c b/kernel/events/core.c index fe33fe15689d..db7b76d6b68a 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -6350,6 +6350,9 @@ static DEFINE_MUTEX(perf_mediated_pmu_mutex); /* !exclude_guest event of PMU with PERF_PMU_CAP_MEDIATED_VPMU */ static inline bool is_include_guest_event(struct perf_event *event) { + if (!event->pmu) + return false; + if ((event->pmu->capabilities & PERF_PMU_CAP_MEDIATED_VPMU) && !event->attr.exclude_guest) return true; @@ -13002,6 +13005,7 @@ static void __pmu_detach_event(struct pmu *pmu, struct perf_event *event, exclusive_event_destroy(event); module_put(pmu->module); + mediated_pmu_unaccount_event(event); event->pmu = NULL; /* force fault instead of UAF */ } -- cgit v1.2.3 From fe3c73d7bc769e7afc252f867a3421fe168b898d Mon Sep 17 00:00:00 2001 From: Andrea Righi Date: Tue, 15 Sep 2026 20:41:01 +0200 Subject: sched/core: Avoid false migration warning for proxy donors Proxy execution can move a blocked donor's scheduling context to the lock owner's CPU even when the donor is migration-disabled. The donor does not execute there, and its original execution CPU remains recorded in wake_cpu. set_task_cpu() warns unconditionally for migration-disabled tasks, so a subsequent proxy migration or the wakeup path returning the donor home triggers a false positive: moving a blocked scheduling context does not violate the migration-disabled execution context. For example, creating a mutex owner on CPU1 and a migration-disabled waiter on CPU0 can trigger the following warning: proxy_migrate_repro: donor blocking on CPU0 with migration disabled proxy_migrate_repro: donor moved from CPU0 to CPU1 WARNING: kernel/sched/core.c:3389 at set_task_cpu+0x1d3/0x280 ... Call Trace: try_to_wake_up+0x43f/0x780 __mutex_unlock_slowpath+0x330/0x540 owner_fn+0x9f/0xc0 [proxy_migrate_repro] ... proxy_migrate_repro: donor woke on CPU0, task_cpu=0 proxy_migrate_repro: completed Exclude blocked proxy donors from the warning. The proxy wakeup path restores an executable placement before clearing the blocked state. Fixes: b049b81bdff6 ("sched: Handle blocked-waiter migration (and return migration)") Signed-off-by: Andrea Righi Signed-off-by: Peter Zijlstra (Intel) Acked-by: John Stultz Link: https://patch.msgid.link/20260915184101.2621252-1-arighi@nvidia.com --- kernel/sched/core.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) (limited to 'kernel') diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 7885ff76e69f..0b846a13c628 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -3351,6 +3351,8 @@ void relax_compatible_cpus_allowed_ptr(struct task_struct *p) void set_task_cpu(struct task_struct *p, unsigned int new_cpu) { unsigned int state = READ_ONCE(p->__state); + bool proxy_migrated = sched_proxy_exec() && p->is_blocked && + task_cpu(p) != p->wake_cpu; /* * We should never call set_task_cpu() on a blocked task, @@ -3386,7 +3388,12 @@ void set_task_cpu(struct task_struct *p, unsigned int new_cpu) */ WARN_ON_ONCE(!cpu_online(new_cpu)); - WARN_ON_ONCE(is_migration_disabled(p)); + /* + * Proxy execution can move a blocked task's scheduling context to any + * CPU without moving its migration-disabled execution context. The + * wakeup path will return the task to a CPU where it can execute. + */ + WARN_ON_ONCE(is_migration_disabled(p) && !proxy_migrated); trace_sched_migrate_task(p, new_cpu); -- cgit v1.2.3 From 8901cee9316d53a5a97398f026c2d59a3043159d Mon Sep 17 00:00:00 2001 From: Kumar Kartikeya Dwivedi Date: Sat, 19 Sep 2026 03:42:10 +0200 Subject: bpf: Compare stack frames in regs_exact() regs_exact() compares the register state up to id, followed by the ID mappings, but does not compare frameno. The PTR_TO_STACK case in regsafe() checks frameno separately, which is bypassed when exact comparison is requested. Consequently, infinite-loop detection can treat pointers to different stack frames as the same pointer and reject a finite loop. For example, initialize fp-8 to zero in the caller and to one in the callee, then pass the caller's fp-8 to the callee as r1: loop: r0 = *(u64 *)(r1 + 0); if r0 != 0 goto done; r1 = r10; r1 += -8; goto loop; done: exit; The loop terminates after reading the callee's slot on its second iteration. At the loop header, however, the only relevant difference is r1's frameno, so exact comparison incorrectly reports an infinite loop. The same problem occurs when the pointer is spilled to the stack. Move frameno into the type-specific metadata union, ahead of id, so the existing prefix comparison in regs_exact() covers it. Ordinary stack pointers do not use another union member. Iterator and IRQ stack-slot states use their dedicated union views and do not need a frame lookup. This also keeps bpf_reg_state at 80 bytes. Since frameno now shares storage with other pointer metadata, it is only meaningful for PTR_TO_STACK registers. Return NULL from bpf_func() for other register types. process_iter_arg(), get_constant_map_key() and is_dynptr_reg_valid_init() look up the frame before checking the register type and would otherwise index frame[] with a byte of the register's map or BTF pointer. They dereference the frame only after their type check. Move the states_maybe_looping() boundary from frameno to precise after the field relocation. Its prefix comparison continues to cover the complete value state and now includes frameno. Continue to ignore precise. Precision marks control whether pruning may ignore scalar ranges; they do not change the represented values, and exact comparison already compares those ranges unconditionally. Marks can also change through backtracking while an ancestor state is still being explored. Fixes: d5b892fd607a ("bpf: make infinite loop detection in is_state_visited() exact") Reported-by: Eduard Zingerman Signed-off-by: Kumar Kartikeya Dwivedi Signed-off-by: Alexei Starovoitov Acked-by: Eduard Zingerman Link: https://patch.msgid.link/20260919014213.1840880-2-memxor@gmail.com --- kernel/bpf/states.c | 7 ++----- 1 file changed, 2 insertions(+), 5 deletions(-) (limited to 'kernel') diff --git a/kernel/bpf/states.c b/kernel/bpf/states.c index e4ec007f7fa6..012b82513a3b 100644 --- a/kernel/bpf/states.c +++ b/kernel/bpf/states.c @@ -644,10 +644,7 @@ static bool regsafe(struct bpf_verifier_env *env, struct bpf_reg_state *rold, return range_within(rold, rcur) && tnum_in(rold->var_off, rcur->var_off); case PTR_TO_STACK: - /* two stack pointers are equal only if they're pointing to - * the same stack frame, since fp-8 in foo != fp-8 in bar - */ - return regs_exact(rold, rcur, idmap) && rold->frameno == rcur->frameno; + return regs_exact(rold, rcur, idmap); case PTR_TO_ARENA: return true; case PTR_TO_INSN: @@ -1126,7 +1123,7 @@ static bool states_maybe_looping(struct bpf_verifier_state *old, fcur = cur->frame[fr]; for (i = 0; i < MAX_BPF_REG; i++) if (memcmp(&fold->regs[i], &fcur->regs[i], - offsetof(struct bpf_reg_state, frameno))) + offsetof(struct bpf_reg_state, precise))) return false; return true; } -- cgit v1.2.3 From bfc888f04588f591851e95c974954cfca58e6c19 Mon Sep 17 00:00:00 2001 From: Kumar Kartikeya Dwivedi Date: Mon, 14 Sep 2026 15:24:42 +0200 Subject: bpf: Bound ownership depth through local kptrs and graph roots Program-allocated objects can own other local objects through referenced kptrs. bpf_obj_free_fields() follows those pointers through __bpf_obj_drop_impl() synchronously, before the object storage is freed through RCU. A self-referential local kptr type therefore permits arbitrarily deep object chains, and dropping the head can exhaust the kernel stack. Long acyclic type chains have the same problem. btf_check_and_fixup_fields() still assumes referenced kptrs only point to kernel types and checks ownership through list and rbtree roots only. Its existing rule is sufficient for graph-only cycles: the target of each graph edge must contain a node, so every type in a cycle has both a root and a node. The rule rejects such a type owning another root, breaking every cycle. It also limits graph-only chains to three types, or two if the first type contains a node, and conservatively rejects longer acyclic chains. The missing local-kptr edges, rather than a missed graph-only cycle, are the bug introduced by support for bpf_kptr_xchg() into local kptrs. Replace that restriction with one bounded ownership walk covering graph roots and local referenced kptrs. Run it after all BTF records have been fixed up, reject cycles and paths deeper than eight record-bearing types, and cache each type's suffix depth while checking it against the remaining budget. This also permits the longer acyclic graph-only layouts rejected by the old rule; update their existing BTF tests accordingly. Keep the bound independent of MAX_CALL_FRAMES because recursive destruction can run below a BPF call chain. A plain local pointee without special-field metadata adds only a final non-recursing drop. Non-owning kptrs and kernel-BTF kptrs do not recurse through local records and remain outside the walk. Include local percpu-kptr edges too, although allocation of percpu objects with special fields is currently forbidden, so that relaxing that restriction cannot bypass the ownership bound. btf_check_and_fixup_fields() continues to initialize graph_root.value_rec, including for separately allocated map records. The ownership relationships belong to immutable program BTF and only need validation at BTF load time. Fixes: b0966c724584 ("bpf: Support bpf_kptr_xchg into local kptr") Reported-by: Nicholas Carlini Suggested-by: Nicholas Carlini Signed-off-by: Kumar Kartikeya Dwivedi Signed-off-by: Alexei Starovoitov Link: https://patch.msgid.link/20260914132444.2564218-2-memxor@gmail.com --- kernel/bpf/btf.c | 134 +++++++++++++++++++++++++++++++++++-------------------- 1 file changed, 86 insertions(+), 48 deletions(-) (limited to 'kernel') diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c index d67a169ba2bb..d870bc5e50bc 100644 --- a/kernel/bpf/btf.c +++ b/kernel/bpf/btf.c @@ -4268,13 +4268,10 @@ int btf_check_and_fixup_fields(const struct btf *btf, struct btf_record *rec) { int i; - /* There are three types that signify ownership of some other type: - * kptr_ref, bpf_list_head, bpf_rb_root. - * kptr_ref only supports storing kernel types, which can't store - * references to program allocated local types. - * - * Hence we only need to ensure that bpf_{list_head,rb_root} ownership - * does not form cycles. + /* + * Check fields which require the complete BTF and initialize runtime + * metadata. Ownership relationships are validated after every record has + * been fixed up. */ if (IS_ERR_OR_NULL(rec) || !(rec->field_mask & (BPF_GRAPH_ROOT | BPF_UPTR))) return 0; @@ -4305,51 +4302,88 @@ int btf_check_and_fixup_fields(const struct btf *btf, struct btf_record *rec) if (!meta) return -EFAULT; rec->fields[i].graph_root.value_rec = meta->record; + } + return 0; +} - /* We need to set value_rec for all root types, but no need - * to check ownership cycle for a type unless it's also a - * node type. - */ - if (!(rec->field_mask & BPF_GRAPH_NODE)) +static int btf_owned_type_idx(const struct btf *btf, struct btf_struct_metas *tab, + const struct btf_field *field) +{ + struct btf_struct_meta *meta; + u32 btf_id; + + if (field->type & BPF_GRAPH_ROOT) { + btf_id = field->graph_root.value_btf_id; + } else if (field->type == BPF_KPTR_REF || field->type == BPF_KPTR_PERCPU) { + if (btf_is_kernel(field->kptr.btf)) + return -ENOENT; + btf_id = field->kptr.btf_id; + } else { + return -ENOENT; + } + + meta = btf_find_struct_meta(btf, btf_id); + if (!meta) + return field->type & BPF_GRAPH_ROOT ? -EFAULT : -ENOENT; + return meta - tab->types; +} + +/* + * Each ownership edge adds kernel frames through bpf_obj_free_fields() and + * __bpf_obj_drop_impl(). Keep the bound deliberately small because object + * destruction can itself run below a BPF call chain. A final pointee without + * special fields is not present in the struct metadata table and adds only a + * non-recursing drop. + */ +#define BTF_MAX_OWNERSHIP_DEPTH 8 + +static int btf_ownership_depth(const struct btf *btf, + struct btf_struct_metas *tab, u8 *depth, + int idx, int depth_left) +{ + const struct btf_record *rec = tab->types[idx].record; + int i, ret, max_depth = 0; + + if (!depth_left) + return -ELOOP; + if (depth[idx]) + goto done; + + for (i = 0; i < rec->cnt; i++) { + ret = btf_owned_type_idx(btf, tab, &rec->fields[i]); + if (ret == -ENOENT) continue; + if (ret < 0) + return ret; + ret = btf_ownership_depth(btf, tab, depth, ret, depth_left - 1); + if (ret < 0) + return ret; + max_depth = max(max_depth, ret); + } + depth[idx] = max_depth + 1; +done: + return depth[idx] > depth_left ? -ELOOP : depth[idx]; +} - /* We need to ensure ownership acyclicity among all types. The - * proper way to do it would be to topologically sort all BTF - * IDs based on the ownership edges, since there can be multiple - * bpf_{list_head,rb_node} in a type. Instead, we use the - * following resaoning: - * - * - A type can only be owned by another type in user BTF if it - * has a bpf_{list,rb}_node. Let's call these node types. - * - A type can only _own_ another type in user BTF if it has a - * bpf_{list_head,rb_root}. Let's call these root types. - * - * We ensure that if a type is both a root and node, its - * element types cannot be root types. - * - * To ensure acyclicity: - * - * When A is an root type but not a node, its ownership - * chain can be: - * A -> B -> C - * Where: - * - A is an root, e.g. has bpf_rb_root. - * - B is both a root and node, e.g. has bpf_rb_node and - * bpf_list_head. - * - C is only an root, e.g. has bpf_list_node - * - * When A is both a root and node, some other type already - * owns it in the BTF domain, hence it can not own - * another root type through any of the ownership edges. - * A -> B - * Where: - * - A is both an root and node. - * - B is only an node. - */ - if (meta->record->field_mask & BPF_GRAPH_ROOT) - return -ELOOP; +static int btf_check_ownership_depth(const struct btf *btf, + struct btf_struct_metas *tab) +{ + u8 *depth; + int i, ret = 0; + + depth = kvcalloc(tab->cnt, sizeof(*depth), GFP_KERNEL | __GFP_NOWARN); + if (!depth) + return -ENOMEM; + + for (i = 0; i < tab->cnt; i++) { + ret = btf_ownership_depth(btf, tab, depth, i, + BTF_MAX_OWNERSHIP_DEPTH); + if (ret < 0) + break; + ret = 0; } - return 0; + kvfree(depth); + return ret; } static void __btf_struct_show(const struct btf *btf, const struct btf_type *t, @@ -6044,6 +6078,10 @@ static struct btf *btf_parse(const union bpf_attr *attr, bpfptr_t uattr, if (err < 0) goto errout_meta; } + + err = btf_check_ownership_depth(btf, struct_meta_tab); + if (err < 0) + goto errout_meta; } err = bpf_log_attr_finalize(attr_log, &env->log); -- cgit v1.2.3 From 3bd46666cfe51e2bd333fb46a0234694ca594230 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Fri, 18 Sep 2026 14:28:37 -1000 Subject: sched_ext: Pass the initial cmask to cid-form ops.enable() The cid-form API has an obvious hole. A task's cid mask is only visible through ops.set_cmask(), which fires on affinity changes and class switches but not when a task enters a scheduler through fork, sub-sched enable or re-home, and there is no p->cpus_ptr equivalent to fall back on. Schedulers work around it by seeding the mask in ops.init_task() from p->cpus_ptr cid by cid, which is subtly wrong: on sub-sched enable and re-home, an affinity change between init_task() and enable() is delivered to the sched the task is still on, and nothing corrects the new sched's copy afterwards. Fix it by adding struct scx_enable_args to cid-form ops.enable() carrying the task's cmask, built in the per-cpu scratch under the rq lock as the task enters the scheduler, and calling set_cmask() with the same mask right after enable(), ahead of set_weight(). A scheduler can then track affinity in set_cmask() alone, and scx_qmap drops its init_task() seed. set_cmask() no longer fires for a cid-form task before it is enabled, and the class-switch republish in switching_to_scx() is limited to the cpu form. This changes the cid-form ops.enable() signature, which is fine as the cid-form API is still considered unreleased. An args struct rather than a bare cmask argument leaves room for more initial state without another signature change, and the cmask travels as a plain arena address because BTF can't type arena struct members yet. v2: The cmask travels as a u64 arena address, cmask_arena_addr, instead of a kernel-typed pointer, with the typing limitation and the planned typed alias documented (Sashiko review). v3: The initial set_cmask() is delivered before set_weight() so that the mask is in place when weight-dependent state is derived (Andrea Righi). Selftest added. Signed-off-by: Tejun Heo Reviewed-by: Andrea Righi --- kernel/sched/ext/ext.c | 92 ++++++++++++++++++++++++++++++--------------- kernel/sched/ext/internal.h | 56 +++++++++++++++++++++++---- 2 files changed, 110 insertions(+), 38 deletions(-) (limited to 'kernel') diff --git a/kernel/sched/ext/ext.c b/kernel/sched/ext/ext.c index f568fd9973f6..ad391a8cbd05 100644 --- a/kernel/sched/ext/ext.c +++ b/kernel/sched/ext/ext.c @@ -447,37 +447,45 @@ static void switch_rq_lock(struct rq *from, struct rq *to) DEFINE_STATIC_KEY_FALSE(__scx_is_cid_type); /** - * scx_call_op_set_cpumask - invoke ops.set_cpumask / ops_cid.set_cmask for @task + * scx_fill_cmask_scratch - Build this cpu's arena cmask from @cpumask + * @sch: scx_sched whose scratch to fill + * @cpumask: cpus to translate into cids + * + * The scratch lives in BPF-writable arena memory and its header can't be + * trusted, so it is rewritten from kernel geometry rather than read. Caller + * must hold an rq lock so this cpu is the sole kernel writer for as long as the + * returned address is in use. + */ +static struct scx_cmask *scx_fill_cmask_scratch(struct scx_sched *sch, + const struct cpumask *cpumask) +{ + struct scx_cmask *kern_va = *this_cpu_ptr(sch->set_cmask_scratch); + struct scx_cmask_ref ref; + + scx_cmask_ref_init_kern(sch, kern_va, 0, num_possible_cpus(), &ref); + scx_cmask_ref_from_cpumask(&ref, cpumask); + return kern_va; +} + +/** + * scx_call_op_set_cpumask - Invoke the set_cpumask or set_cmask op for @task * @sch: scx_sched being invoked * @rq: rq to update as the currently-locked rq, or NULL * @task: task whose affinity is changing * @cpumask: new cpumask * - * For cid-form schedulers, translate @cpumask to a cmask via the per-cpu - * scratch in cid.c and dispatch through the ops_cid union view. Caller - * must hold @rq's rq lock so this_cpu_ptr is stable across the call. + * For cid-form schedulers, translate @cpumask to a cmask in the per-cpu scratch + * and dispatch through the ops_cid union view. Caller must hold @rq's rq lock. */ static inline void scx_call_op_set_cpumask(struct scx_sched *sch, struct rq *rq, struct task_struct *task, const struct cpumask *cpumask) { - if (scx_is_cid_type()) { - struct scx_cmask *kern_va = *this_cpu_ptr(sch->set_cmask_scratch); - struct scx_cmask_ref ref; - - /* - * Build the per-cpu arena cmask from kernel geometry via @ref, - * never reading its BPF-writable header. set_cmask()'s __arena - * argument takes the kernel address and the struct_ops - * trampoline rebases it into BPF's arena pointer form. The rq - * lock makes this cpu the sole kernel writer. - */ - scx_cmask_ref_init_kern(sch, kern_va, 0, num_possible_cpus(), &ref); - scx_cmask_ref_from_cpumask(&ref, cpumask); - SCX_CALL_CID_OP_TASK(sch, set_cmask, rq, task, kern_va); - } else { + if (scx_is_cid_type()) + SCX_CALL_CID_OP_TASK(sch, set_cmask, rq, task, + scx_fill_cmask_scratch(sch, cpumask)); + else SCX_CALL_OP_TASK(sch, set_cpumask, rq, task, cpumask); - } } enum scx_dsq_iter_flags { @@ -3634,8 +3642,12 @@ static void set_cpus_allowed_scx(struct task_struct *p, * * Fine-grained memory write control is enforced by BPF making the const * designation pointless. Cast it away when calling the operation. + * + * The cid form receives the initial mask when the task is enabled and + * hears about changes only afterwards, see struct scx_enable_args. */ - if (SCX_HAS_OP(sch, set_cpumask)) + if (SCX_HAS_OP(sch, set_cpumask) && + (!scx_is_cid_type() || scx_get_task_state(p) == SCX_TASK_ENABLED)) scx_call_op_set_cpumask(sch, task_rq(p), p, (struct cpumask *)p->cpus_ptr); } @@ -3944,8 +3956,27 @@ static void __scx_enable_task(struct scx_sched *sch, struct task_struct *p) p->scx.weight = sched_weight_to_cgroup(weight); - if (SCX_HAS_OP(sch, enable)) - SCX_CALL_OP_TASK(sch, enable, rq, p); + if (SCX_HAS_OP(sch, enable)) { + if (scx_is_cid_type()) { + struct scx_cmask *cmask = scx_fill_cmask_scratch(sch, p->cpus_ptr); + struct scx_enable_args args = { + .cmask_arena_addr = scx_kaddr_to_arena(sch, cmask), + }; + + SCX_CALL_CID_OP_TASK(sch, enable, rq, p, &args); + } else { + SCX_CALL_OP_TASK(sch, enable, rq, p); + } + } + + /* + * The initial mask also goes out through set_cmask() so a scheduler can + * track affinity there alone, and before set_weight() so that the mask + * is in place when weight-dependent state is derived, see struct + * scx_enable_args. + */ + if (scx_is_cid_type() && SCX_HAS_OP(sch, set_cpumask)) + scx_call_op_set_cpumask(sch, rq, p, p->cpus_ptr); if (SCX_HAS_OP(sch, set_weight)) SCX_CALL_OP_TASK(sch, set_weight, rq, p, p->scx.weight); @@ -4288,9 +4319,10 @@ static void switching_to_scx(struct rq *rq, struct task_struct *p) /* * set_cpus_allowed_scx() is not called while @p is associated with a - * different scheduler class. Keep the BPF scheduler up-to-date. + * different scheduler class. Keep the BPF scheduler up-to-date. The cid + * form gets its mask from scx_enable_task(). */ - if (SCX_HAS_OP(sch, set_cpumask)) + if (!scx_is_cid_type() && SCX_HAS_OP(sch, set_cpumask)) scx_call_op_set_cpumask(sch, rq, p, (struct cpumask *)p->cpus_ptr); } @@ -8374,10 +8406,11 @@ static struct bpf_struct_ops bpf_sched_ext_ops = { /* * cid-form cfi stubs. Stubs whose signatures match the cpu-form (param types * identical, only param names differ across structs) are reused. Some need - * fresh stubs, set_cmask due to an argument type difference and the sub-sched - * notifiers because no cpu-form stub exists to reuse. + * fresh stubs, set_cmask and enable due to argument differences and the + * sub-sched notifiers because no cpu-form stub exists to reuse. */ static void sched_ext_ops_cid__set_cmask(struct task_struct *p, const struct scx_cmask *cmask__arena) {} +static void sched_ext_ops_cid__enable(struct task_struct *p, struct scx_enable_args *args) {} static void sched_ext_ops__sub_caps_updated(const struct scx_cmask *cmask__arena, u64 caps) {} static void sched_ext_ops__sub_ecaps_updated(s32 cid, u64 before, u64 after) {} @@ -8398,7 +8431,7 @@ static struct sched_ext_ops_cid __bpf_ops_sched_ext_ops_cid = { .update_idle = sched_ext_ops__update_idle, .init_task = sched_ext_ops__init_task, .exit_task = sched_ext_ops__exit_task, - .enable = sched_ext_ops__enable, + .enable = sched_ext_ops_cid__enable, .disable = sched_ext_ops__disable, #ifdef CONFIG_EXT_GROUP_SCHED .cpuctl_init = sched_ext_ops__cgroup_init, @@ -10421,8 +10454,7 @@ __bpf_kfunc const void *scx_bpf_online_cmask(const struct bpf_prog_aux *aux) if (unlikely(!online)) return NULL; - /* BPF rebases by the low 32 bits, like __arena callback args */ - return (void *)((unsigned long)online - sch->arena_kern_base); + return (void *)scx_kaddr_to_arena(sch, online); } /** diff --git a/kernel/sched/ext/internal.h b/kernel/sched/ext/internal.h index d150de10a5c9..1df8f583b0ec 100644 --- a/kernel/sched/ext/internal.h +++ b/kernel/sched/ext/internal.h @@ -250,6 +250,31 @@ struct scx_exit_task_args { bool cancelled; }; +/** + * struct scx_enable_args - Argument container for cid-form ops.enable() + * @cmask_arena_addr: BPF arena address of the cmask of cids the task may run on + * + * @cmask_arena_addr is the task's affinity as it enters the scheduler. + * set_cmask() delivers the same mask right after enable(), before set_weight() + * and the first enqueue, then every affinity change afterwards, and is never + * called before enable(). A scheduler may therefore track affinity in + * set_cmask() alone. + * + * The kernel builds the mask in the scheduler arena from its own geometry, so + * the header is valid regardless of what the scheduler last wrote there. The + * memory is per-cpu scratch reused once the callback returns: copy the bits + * out, don't keep the address. The set_cmask() argument follows the same rules. + * + * The address is a plain value rather than a typed pointer because BTF can't + * mark a struct member as an arena pointer yet and a pointer member would reach + * the program typed as a kernel pointer. Cast it to struct scx_cmask __arena * + * before use. Once arena members can be typed, a typed alias will join this + * field in an anonymous union at the same offset. + */ +struct scx_enable_args { + u64 cmask_arena_addr; +}; + /* argument container for ops.cgroup_init() */ struct scx_cgroup_init_args { /* the weight of the cgroup [1..10000] */ @@ -1037,6 +1062,7 @@ struct sched_ext_ops { * - dispatch -> dispatch (cpu arg is now cid) * - update_idle -> update_idle (cpu arg is now cid) * - set_cpumask -> set_cmask (cmask instead of cpumask) + * - enable -> enable (takes struct scx_enable_args) * - cpu_online -> cid_online * - cpu_offline -> cid_offline * - dump_cpu -> dump_cid @@ -1070,7 +1096,7 @@ struct sched_ext_ops_cid { struct scx_init_task_args *args); void (*exit_task)(struct task_struct *p, struct scx_exit_task_args *args); - void (*enable)(struct task_struct *p); + void (*enable)(struct task_struct *p, struct scx_enable_args *args); void (*disable)(struct task_struct *p); void (*dump)(struct scx_dump_ctx *ctx); void (*dump_cid)(struct scx_dump_ctx *ctx, s32 cid, bool idle); @@ -1533,7 +1559,8 @@ struct scx_sched { * by BUILD_BUG_ON in scx_init()). The anonymous union lets the kernel * access either view of the same storage without function-pointer * casts: use .ops for cpu-form and shared fields, .ops_cid for the - * cid-renamed callbacks (set_cmask, select_cid, cid_online, ...). + * callbacks whose cid-form signature differs (set_cmask, enable, + * select_cid, cid_online, ...). */ union { struct sched_ext_ops ops; @@ -1556,9 +1583,9 @@ struct scx_sched { uintptr_t arena_kern_base; /* - * Per-CPU arena cmask used by scx_call_op_set_cpumask() to hand a cmask - * to ops_cid.set_cmask(). The kernel writes through the stored kern_va - * and passes it to the callback's __arena argument. + * Per-CPU arena cmask the kernel fills from a task's cpumask and hands + * to ops_cid.enable() and ops_cid.set_cmask(). The stored pointers are + * the kernel addresses. */ struct scx_cmask * __percpu *set_cmask_scratch; struct scx_cmask *online_cmask; @@ -1669,6 +1696,19 @@ static inline void *scx_arena_to_kaddr(struct scx_sched *sch, const void *bpf_pt return (void *)(sch->arena_kern_base + (u32)(uintptr_t)bpf_ptr); } +/** + * scx_kaddr_to_arena - Translate a kernel arena address to the BPF form + * @sch: scheduler whose arena hosts @kaddr + * @kaddr: kernel address inside @sch's arena + * + * __arena callback arguments need no translation. Addresses handed to BPF any + * other way, such as struct fields and kfunc return values, go through this. + */ +static inline uintptr_t scx_kaddr_to_arena(struct scx_sched *sch, const void *kaddr) +{ + return (uintptr_t)kaddr - sch->arena_kern_base; +} + enum scx_wake_flags { /* expose select WF_* flags as enums */ SCX_WAKE_FORK = WF_FORK, @@ -2302,9 +2342,9 @@ do { \ } while (0) /* - * Dispatch a task op through the cid-form ops_cid table. Only set_cmask() needs - * this: it takes an arena cmask address instead of a cpumask, so it cannot be - * invoked via its cpu-form set_cpumask() slot. + * Dispatch a task op through the cid-form ops_cid table, for the ops whose + * cid-form signature differs from the cpu-form slot: set_cmask() takes an arena + * cmask instead of a cpumask and enable() takes scx_enable_args. */ #define SCX_CALL_CID_OP_TASK(sch, op, locked_rq, task, args...) \ __SCX_CALL_OP_TASK(sch, ops_cid, op, locked_rq, task, ##args) -- cgit v1.2.3 From c21eaa72f02fc6e85621cbe09d303d8fb8bd39cd Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Wed, 16 Sep 2026 20:48:30 +0200 Subject: posix-cpu-timers: Prevent freeing a timer which is queued on the expiry list Kijo analyzed another race in the POSIX CPU timer code: Commit bf635681c906 converted cpu_timer::firing from a tristate value to a boolean. This lost the distinction between "not owned by the firing list" and "still owned, but delivery was canceled". The resulting race is: expiry handler timer_settime() timer_delete() -------------- --------------- -------------- collect timer onto private firing list firing = true observes firing = true firing = false return TIMER_RETRY wait for handler observes firing = false finish deletion unhash and free timer resume list traversal read freed elist.next -> UAF The firing bit is clearly the wrong indicator since that commit. Check whether the timer is queued on the expiry list or not instead. If it is queued clear the firing bit to prevent signal delivery as before and return TIMER_RETRY so the caller unlocks the timer which allows the expiry code to make progress and remove it from the list. Fixes: bf635681c906 ("posix-cpu-timers: Cleanup the firing logic") Reported-by: Kijo Park Debugged-by: Kijo Park Signed-off-by: Thomas Gleixner Tested-by: Kijo Park Reviewed-by: Frederic Weisbecker Cc: stable@vger.kernel.org --- kernel/time/posix-cpu-timers.c | 40 ++++++++++++++++++++++------------------ 1 file changed, 22 insertions(+), 18 deletions(-) (limited to 'kernel') diff --git a/kernel/time/posix-cpu-timers.c b/kernel/time/posix-cpu-timers.c index d73d31c7994f..0bf4fcd969c8 100644 --- a/kernel/time/posix-cpu-timers.c +++ b/kernel/time/posix-cpu-timers.c @@ -408,6 +408,7 @@ static int posix_cpu_timer_create(struct k_itimer *new_timer) new_timer->kclock = &clock_posix_cpu; timerqueue_init(&new_timer->it.cpu.node); + INIT_LIST_HEAD(&new_timer->it.cpu.elist); new_timer->it.cpu.pid = get_pid(pid); rcu_read_unlock(); return 0; @@ -565,6 +566,24 @@ static struct task_struct *timer_lock_sighand(struct k_itimer *timer, unsigned l return NULL; } +/* + * If the timer is queued on the expiry list, then it cannot be dequeued because + * the firing list is not protected by sighand->lock. The delivery path is + * waiting for the timer lock. So go back, unlock and retry. + */ +static bool posix_cpu_timer_on_expiry_list(struct k_itimer *timer) +{ + if (list_empty(&timer->it.cpu.elist)) + return false; + + /* + * Prevent signal delivery as there is no point in delivering a signal + * which is made obsolete right away. + */ + timer->it.cpu.firing = false; + return true; +} + /* * Clean up a CPU-clock timer that is about to be destroyed. * This is called from timer deletion with the timer already locked. @@ -580,18 +599,10 @@ static int posix_cpu_timer_del(struct k_itimer *timer) p = timer_lock_sighand(timer, &flags); if (likely(p)) { - if (timer->it.cpu.firing) { - /* - * Prevent signal delivery. The timer cannot be dequeued - * because it is on the firing list which is not protected - * by sighand->lock. The delivery path is waiting for - * the timer lock. So go back, unlock and retry. - */ - timer->it.cpu.firing = false; + if (posix_cpu_timer_on_expiry_list(timer)) ret = TIMER_RETRY; - } else { + else disarm_timer(timer, p); - } unlock_task_sighand(p, &flags); } @@ -731,14 +742,7 @@ static int posix_cpu_timer_set(struct k_itimer *timer, int timer_flags, /* Retrieve the current expiry time before disarming the timer */ old_expires = cpu_timer_getexpires(ctmr); - if (unlikely(timer->it.cpu.firing)) { - /* - * Prevent signal delivery. The timer cannot be dequeued - * because it is on the firing list which is not protected - * by sighand->lock. The delivery path is waiting for - * the timer lock. So go back, unlock and retry. - */ - timer->it.cpu.firing = false; + if (posix_cpu_timer_on_expiry_list(timer)) { ret = TIMER_RETRY; } else { cpu_timer_dequeue(ctmr); -- cgit v1.2.3 From a11212910cf09b2fe8db9afa41ef60c4f81879c5 Mon Sep 17 00:00:00 2001 From: Yuqi Xu Date: Sat, 19 Sep 2026 16:45:02 +0800 Subject: bpf: Check params size before reading reserved fields bpf_crypto_ctx_create() is a kfunc whose second argument is declared with the __sz annotation, so the verifier only guarantees that params__sz bytes of params are valid. The function nevertheless reads params->reserved[0] and params->reserved[1] (offsets 14 and 15) before comparing params__sz against the size of struct bpf_crypto_params, so a BPF program can pass a shorter buffer and have the kernel read past the region that was validated for it. Move the size check in front of the reserved field reads. Fixes: 3e1c6f35409f ("bpf: make common crypto API for TC/XDP programs") Reported-by: Vega Signed-off-by: Yuqi Xu Signed-off-by: Alexei Starovoitov Reviewed-by: Ren Wei Link: https://patch.msgid.link/4f3ab4b03e79017e215521743996555439bf0bb3.1789802413.git.xuyuqiabc@gmail.com --- kernel/bpf/crypto.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) (limited to 'kernel') diff --git a/kernel/bpf/crypto.c b/kernel/bpf/crypto.c index 51f89cecefb4..3f3fe2450fc6 100644 --- a/kernel/bpf/crypto.c +++ b/kernel/bpf/crypto.c @@ -149,8 +149,9 @@ bpf_crypto_ctx_create(const struct bpf_crypto_params *params, u32 params__sz, const struct bpf_crypto_type *type; struct bpf_crypto_ctx *ctx; - if (!params || params->reserved[0] || params->reserved[1] || - params__sz != sizeof(struct bpf_crypto_params)) { + if (!params || + params__sz != sizeof(struct bpf_crypto_params) || + params->reserved[0] || params->reserved[1]) { *err = -EINVAL; return NULL; } -- cgit v1.2.3 From 79a9172f3ab4ad8392c5e5c8944b9b7710ade620 Mon Sep 17 00:00:00 2001 From: Xu Yunxiang Date: Mon, 21 Sep 2026 05:04:21 +0800 Subject: bpf: Reject non-negative offsets in stack_slot_obj_get_spi() bpf_get_spi() computes (-off - 1) / BPF_REG_SIZE using C division, which truncates toward zero. For off == 0, this produces spi 0, the same index used by the valid stack slot at fp-8. stack_slot_obj_get_spi() currently checks alignment and the resulting spi bounds, but does not reject the non-negative offset itself. It can therefore validate a PTR_TO_STACK register holding fp+0 against an iterator stored at fp-8 even though the runtime receives the actual fp+0 pointer. An effectful iterator kfunc can then interpret memory outside the BPF stack as iterator state. Reject non-negative offsets before converting the offset to an spi. All valid stack objects begin at a negative offset from the frame pointer. Fixes: 06accc8779c1 ("bpf: add support for open-coded iterator loops") Signed-off-by: Xu Yunxiang Signed-off-by: Andrii Nakryiko Reviewed-by: Sun Jian Link: https://lore.kernel.org/bpf/20260920210423.345636-2-xyx2021@mail.ustc.edu.cn --- kernel/bpf/verifier.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'kernel') diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 02be326f235c..dd8bb179d39e 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -567,7 +567,7 @@ static int stack_slot_obj_get_spi(struct bpf_verifier_env *env, struct bpf_reg_s } off = reg->var_off.value; - if (off % BPF_REG_SIZE) { + if (off >= 0 || off % BPF_REG_SIZE) { verbose(env, "cannot pass in %s at an offset=%d\n", obj_kind, off); return -EINVAL; } -- cgit v1.2.3 From 0d6526f82c3cdefcca47f73f5fc08dc6f335eac6 Mon Sep 17 00:00:00 2001 From: Tim Chen Date: Mon, 21 Sep 2026 17:37:22 -0700 Subject: sched/cache: Keep nr_pref_llc_running in the runnable domain, to fix LLC mis-scheduling bug alb_break_llc() decides whether to break LLC preference during active load balance. It does so by testing that every runnable fair task on the source rq prefers its LLC: env->src_rq->nr_pref_llc_running == env->src_rq->cfs.h_nr_runnable But the two counters cover different sets. nr_pref_llc_running is updated in account_llc_enqueue()/account_llc_dequeue(), next to cfs_rq->nr_queued, so it follows queued tasks. h_nr_runnable is updated in set_delayed()/ clear_delayed() and drops delay-dequeued tasks. So under DELAY_DEQUEUE, a preferring task that goes to sleep stays counted in nr_pref_llc_running while h_nr_runnable falls. The equality then breaks, alb_break_llc() returns false, and active balance is free to pull a task off its preferred LLC. Active balance only moves runnable tasks, and this is the only LLC check it consults: once the stopper runs, LBF_ACTIVE_LB skips the per-task test in can_migrate_task(). The runnable set is the one we want. Fix it on the counter side. A task should be counted in nr_pref_llc_running exactly while it is both queued on its preferred LLC (pref_llc_queued) and runnable (!sched_delayed). Define that membership once in task_pref_llc_runnable(), and adjust the counter only through pref_llc_running_inc()/pref_llc_running_dec() from the four sites that change either input: account_llc_enqueue(), account_llc_dequeue(), set_delayed() and clear_delayed(). Gating every update on the same predicate keeps the delay, wake and dequeue paths from double-counting or underflowing; see the comments at those sites for the ordering. nr_llc_running and sd->llc_counts are not touched and stay on queued semantics. Fixes: 714059f79ff0 ("sched/cache: Handle moving single tasks to/from their preferred LLC") Closes: https://lore.kernel.org/lkml/20260827135000.735138-1-zhanxusheng@xiaomi.com/ Reported-by: Zhan Xusheng Suggested-by: Chen Yu Signed-off-by: Tim Chen Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Ingo Molnar Reviewed-by: Kayra Cizmeci Cc: # v7.2.x Link: https://patch.msgid.link/06af61afedac32e6477f57feb4d658f6c411c3af.1790035273.git.tim.c.chen@linux.intel.com --- kernel/sched/fair.c | 63 ++++++++++++++++++++++++++++++++++++++++++++++++----- 1 file changed, 58 insertions(+), 5 deletions(-) (limited to 'kernel') diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 7455a83a6a99..de3d589fa8eb 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -1546,6 +1546,28 @@ static bool invalid_llc_nr(struct mm_struct *mm, struct task_struct *p, (scale * per_cpu(sd_llc_size, cpu))); } +/* + * A task counts in nr_pref_llc_running while it is queued on its preferred + * LLC (pref_llc_queued) and runnable (!sched_delayed), keeping the counter in + * the runnable domain so alb_break_llc() can compare it with h_nr_runnable. + */ +static bool task_pref_llc_runnable(struct task_struct *p) +{ + return p->pref_llc_queued && !p->se.sched_delayed; +} + +static void pref_llc_running_inc(struct rq *rq, struct task_struct *p) +{ + if (task_pref_llc_runnable(p)) + rq->nr_pref_llc_running++; +} + +static void pref_llc_running_dec(struct rq *rq, struct task_struct *p) +{ + if (task_pref_llc_runnable(p)) + rq->nr_pref_llc_running--; +} + static void account_llc_enqueue(struct rq *rq, struct task_struct *p) { int pref_llc, pref_llc_queued; @@ -1557,7 +1579,6 @@ static void account_llc_enqueue(struct rq *rq, struct task_struct *p) pref_llc_queued = (pref_llc == task_llc(p)); rq->nr_llc_running++; - rq->nr_pref_llc_running += pref_llc_queued; /* * Record whether p is enqueued on its preferred @@ -1575,6 +1596,9 @@ static void account_llc_enqueue(struct rq *rq, struct task_struct *p) */ p->pref_llc_queued = pref_llc_queued; + /* Skipped while delayed; clear_delayed() adds it back on wake. */ + pref_llc_running_inc(rq, p); + sd = rcu_dereference_all(rq->sd); if (sd && (unsigned int)pref_llc < sd->llc_max) sd->llc_counts[pref_llc]++; @@ -1591,7 +1615,12 @@ static void account_llc_dequeue(struct rq *rq, struct task_struct *p) rq->nr_llc_running--; if (p->pref_llc_queued) { - rq->nr_pref_llc_running--; + /* + * Skipped if still delayed (set_delayed() already removed it); + * clearing pref_llc_queued below also stops clear_delayed() + * from re-adding it. + */ + pref_llc_running_dec(rq, p); /* * Update the status in case * other logic might query @@ -1995,6 +2024,7 @@ void init_sched_mm(struct task_struct *p) * polluting account_llc_enqueue(). */ p->preferred_llc = -1; + p->pref_llc_queued = 0; } #else /* CONFIG_SCHED_CACHE */ @@ -2016,6 +2046,10 @@ static void account_llc_enqueue(struct rq *rq, struct task_struct *p) {} static void account_llc_dequeue(struct rq *rq, struct task_struct *p) {} +static void pref_llc_running_inc(struct rq *rq, struct task_struct *p) {} + +static void pref_llc_running_dec(struct rq *rq, struct task_struct *p) {} + #endif /* CONFIG_SCHED_CACHE */ /* @@ -6390,15 +6424,27 @@ static __always_inline void return_cfs_rq_runtime(struct cfs_rq *cfs_rq); static void set_delayed(struct sched_entity *se) { - se->sched_delayed = 1; - /* * Delayed se of cfs_rq have no tasks queued on them. * Do not adjust h_nr_runnable since __dequeue_task() * will account it for blocked tasks. + * + * This check can be removed because when flat pick + * patches get merged as only task can get delayed, + * same for clear_delayed(). */ - if (!entity_is_task(se)) + if (!entity_is_task(se)) { + se->sched_delayed = 1; return; + } + + /* + * Drop a task leaving the runnable set. + * Needs to be called before sched_delayed is set. + * clear_delayed() mirrors this after clearing the flag. + */ + pref_llc_running_dec(rq_of(cfs_rq_of(se)), task_of(se)); + se->sched_delayed = 1; for_each_sched_entity(se) { struct cfs_rq *cfs_rq = cfs_rq_of(se); @@ -6420,6 +6466,13 @@ static void clear_delayed(struct sched_entity *se) if (!entity_is_task(se)) return; + /* + * Re-add on wake, after sched_delayed is cleared. On a final delayed + * dequeue account_llc_dequeue() already cleared pref_llc_queued, so + * this does nothing. + */ + pref_llc_running_inc(rq_of(cfs_rq_of(se)), task_of(se)); + for_each_sched_entity(se) { struct cfs_rq *cfs_rq = cfs_rq_of(se); -- cgit v1.2.3 From d6013e2465d98d524b030a81c1223882a1bb7e4c Mon Sep 17 00:00:00 2001 From: Lu Wang Date: Mon, 21 Sep 2026 17:37:23 -0700 Subject: sched/cache: Honor migrate_llc_task semantics in active load balance, to fix LLC mis-scheduling bug Cache aware scheduling introduced the migrate_llc_task migration type to direct tasks toward their preferred LLC, but its semantics can be lost when passive load balance falls back to active load balance (ALB). This may allow ALB to select a candidate whose preferred LLC does not match the destination, moving it away from its preferred LLC. Example scenario: src_rq has two runnable tasks, p1 and p2. p1 prefers dst_rq (dst_llc), while p2 prefers src_rq (src_llc). In this case, migrate_llc_task is set because src_rq has at least one task, p1, that wants to migrate to dst_rq. In ALB, can_migrate_task() finds p2 and returns true for it, thus moving p2 out of its preferred LLC. Solution: The CPU stopper in ALB constructs a fresh lb_env that does not inherit migration_type from the passive load-balance pass. Two approaches are possible: (a) Add a new member to struct rq so ALB can inherit migrate_llc_task from the passive LB that triggered it. (b) Define a new flag LBF_ACTIVE_LB_LLC and select the stopper callback at kick time to preserve the migration semantics across the asynchronous boundary. We choose (b) because it avoids passing migration_type through the stopper, which would affect the meaning of migration_type for delayed-dequeue tasks. Fixes: e4c9a4cb244a ("sched/cache: Add migrate_llc_task migration type for cache-aware balancing") Suggested-by: Chen Yu Signed-off-by: Lu Wang Signed-off-by: Tim Chen Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Ingo Molnar Reviewed-by: Tim Chen Reviewed-by: Chen Yu Cc: # v7.2.x Link: https://patch.msgid.link/cb39f64a17fc2b76097264aaec74a2d6dfff4315.1790035273.git.tim.c.chen@linux.intel.com --- kernel/sched/fair.c | 57 +++++++++++++++++++++++++++++++++++++++++++++++------ 1 file changed, 51 insertions(+), 6 deletions(-) (limited to 'kernel') diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index de3d589fa8eb..514bd54ccd56 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -10448,6 +10448,7 @@ enum migration_type { #define LBF_SOME_PINNED 0x08 #define LBF_ACTIVE_LB 0x10 #define LBF_LLC_PINNED 0x20 +#define LBF_ACTIVE_LB_LLC 0x40 struct lb_env { struct sched_domain *sd; @@ -10866,6 +10867,21 @@ alb_break_llc(struct lb_env *env) return false; } +/* + * Returns true if p's preferred LLC does not match the destination CPU + * under migrate_llc_task semantics. Passive LB passes migrate_llc_task + * in env->migration_type, while active LB carries LBF_ACTIVE_LB_LLC in + * env->flags to avoid overwriting env->migration_type. + */ +static inline bool +migrate_llc_task_wrong_dst(struct task_struct *p, struct lb_env *env) +{ + return sched_cache_enabled() && + (env->migration_type == migrate_llc_task || + env->flags & LBF_ACTIVE_LB_LLC) && + READ_ONCE(p->preferred_llc) != llc_id(env->dst_cpu); +} + /* * Check if migrating task p from env->src_cpu to * env->dst_cpu breaks LLC localiy. @@ -10894,8 +10910,7 @@ static bool migrate_degrades_llc(struct task_struct *p, struct lb_env *env) * run on env->dst_cpu, skip the tasks do not prefer * env->dst_cpu, and find the one that prefers. */ - if (env->migration_type == migrate_llc_task && - READ_ONCE(p->preferred_llc) != llc_id(env->dst_cpu)) + if (migrate_llc_task_wrong_dst(p, env)) return true; if (can_migrate_llc_task(env, p) != mig_forbid) @@ -10917,6 +10932,12 @@ alb_break_llc(struct lb_env *env) return false; } +static inline bool +migrate_llc_task_wrong_dst(struct task_struct *p, struct lb_env *env) +{ + return false; +} + static inline bool migrate_degrades_llc(struct task_struct *p, struct lb_env *env) { @@ -11016,7 +11037,7 @@ int can_migrate_task(struct task_struct *p, struct lb_env *env) * 4) too many balance attempts have failed. */ if (env->flags & LBF_ACTIVE_LB) - return 1; + return !migrate_llc_task_wrong_dst(p, env); degrades = migrate_degrades_locality(p, env); if (!degrades) { @@ -13415,6 +13436,20 @@ static int need_active_balance(struct lb_env *env) } static int active_load_balance_cpu_stop(void *data); +static int active_load_balance_llc_cpu_stop(void *data); + +/* + * migration_type is checked elsewhere to decide migration policy, so + * it shouldn't be repurposed just to flag an LLC-directed active + * balance across the stopper. Pick the callback here instead. + */ +static inline cpu_stop_fn_t alb_stop_fn(struct lb_env *env) +{ + if (env->migration_type == migrate_llc_task) + return active_load_balance_llc_cpu_stop; + + return active_load_balance_cpu_stop; +} static int should_we_balance(struct lb_env *env) { @@ -13760,7 +13795,7 @@ more_balance: } if (active_balance) { stop_one_cpu_nowait(cpu_of(busiest), - active_load_balance_cpu_stop, busiest, + alb_stop_fn(&env), busiest, &busiest->active_balance_work); } preempt_enable(); @@ -13865,7 +13900,7 @@ update_next_balance(struct sched_domain *sd, unsigned long *next_balance) * least 1 task to be running on each physical CPU where possible, and * avoids physical / logical imbalances. */ -static int active_load_balance_cpu_stop(void *data) +static int __active_load_balance_cpu_stop(void *data, unsigned int lb_flags) { struct rq *busiest_rq = data; int busiest_cpu = cpu_of(busiest_rq); @@ -13915,7 +13950,7 @@ static int active_load_balance_cpu_stop(void *data) .src_cpu = busiest_rq->cpu, .src_rq = busiest_rq, .idle = CPU_IDLE, - .flags = LBF_ACTIVE_LB, + .flags = LBF_ACTIVE_LB | lb_flags, }; schedstat_inc(sd->alb_count); @@ -13943,6 +13978,16 @@ out_unlock: return 0; } +static int active_load_balance_cpu_stop(void *data) +{ + return __active_load_balance_cpu_stop(data, 0); +} + +static int active_load_balance_llc_cpu_stop(void *data) +{ + return __active_load_balance_cpu_stop(data, LBF_ACTIVE_LB_LLC); +} + /* * Scale the max sched_balance_rq interval with the number of CPUs in the system. * This trades load-balance latency on larger machines for less cross talk. -- cgit v1.2.3 From 28f9c0e0a0b94c5d3e1b634db545f6e1f94858c5 Mon Sep 17 00:00:00 2001 From: Tim Chen Date: Mon, 21 Sep 2026 17:37:24 -0700 Subject: sched/cache: Decouple sched_cache_group from mm to fix UAF Currently the sched cache grouping is by mm and the scheduling statistics sched_cache_stat lives in the mm structure. This ties the life cycle of scheduling stats with mm. In account_mm_sched(), the scheduling stats are accessed by task->mm->sc_stat. However, a task may be switching mm on one CPU when another CPU is running account_mm_sched(), and possibly accessing the old mm that was freed. This problem was found when running tests with KASAN by Hyunwoo: https://lore.kernel.org/lkml/apPb-Dr4nPYuHQOK@v4bel/ Instead of serializing the mm access by introducing extra acquisition of rq lock in the mm free path, extract sched_cache_stat from mm_struct, rename it as sched_cache_group and manage its life cycle apart from mm_struct with its own ref counting. This allows us in the next patch access sched_cache_group directly from task, and add a refcount on sched_cache_group when a task links to it. This prevents the use after free issue when accessing stale and released old mm and its sched cache stat a task switches to a new mm while account_mm_sched() is done elsewhere. The other benefit of this restructure is in the future, the grouping of tasks to a LLC would have the flexibility to be associated with a user defined grouping, or cgroup, cookie group, numa_group or others instead of just with a single mm address space. Rename sched_cache_stat to sched_cache_group and turn it into a refcounted object allocated from mm_struct. The mm_struct now holds a pointer (sched_cache_grp) to this object instead of embedding it. Fixes: df0d98475954 ("sched/cache: Introduce infrastructure for cache-aware load balancing") Closes: https://lore.kernel.org/lkml/apPb-Dr4nPYuHQOK@v4bel/ Closes: https://lore.kernel.org/all/343a7e07-7fad-4979-9c9b-82ec038c293c@linux.dev/ Reported-by: Hyunwoo Kim Reported-by: Zenghui Yu (Huawei) Co-developed-by: Chen Yu Signed-off-by: Chen Yu Signed-off-by: Tim Chen Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Ingo Molnar Cc: #7.2.x Link: https://patch.msgid.link/91fd1e3266707c865bc9abecfb3e17bc676712df.1790035273.git.tim.c.chen@linux.intel.com --- kernel/exit.c | 11 +++- kernel/sched/fair.c | 173 ++++++++++++++++++++++++++++++++++++++-------------- 2 files changed, 135 insertions(+), 49 deletions(-) (limited to 'kernel') diff --git a/kernel/exit.c b/kernel/exit.c index 424c44a42a4d..024350e9b48c 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -558,18 +558,23 @@ void mm_update_next_owner(struct mm_struct *mm) */ static void exit_mm_sched_cache(struct mm_struct *mm) { + struct sched_cache_group *grp; unsigned long fp, sub; if (!current->total_numa_faults) return; /* * No lock protection due to performance considerations. - * Make sure mm->sc_stat.footprint does not become + * Make sure the group footprint does not become * negative. */ - fp = READ_ONCE(mm->sc_stat.footprint); + grp = READ_ONCE(mm->sched_cache_grp); + if (!grp) + return; + + fp = READ_ONCE(grp->footprint); sub = min(fp, current->total_numa_faults); - WRITE_ONCE(mm->sc_stat.footprint, fp - sub); + WRITE_ONCE(grp->footprint, fp - sub); } #else static inline void exit_mm_sched_cache(struct mm_struct *mm) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 514bd54ccd56..f0a9586332fd 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -1492,12 +1492,17 @@ static bool exceed_llc_capacity(struct mm_struct *mm, int cpu) return true; if (static_branch_likely(&sched_numa_balancing)) { + struct sched_cache_group *grp = READ_ONCE(mm->sched_cache_grp); + + if (!grp) + return true; + /* * TBD: RDT exclusive LLC ways reserved should be * excluded. */ llc = sd->llc_bytes; - footprint = READ_ONCE(mm->sc_stat.footprint); + footprint = READ_ONCE(grp->footprint); /* * Scale the LLC size by 256*llc_aggr_tolerance @@ -1529,6 +1534,7 @@ static bool exceed_llc_capacity(struct mm_struct *mm, int cpu) static bool invalid_llc_nr(struct mm_struct *mm, struct task_struct *p, int cpu) { + struct sched_cache_group *grp; int scale; if (get_nr_threads(p) <= 1) @@ -1542,7 +1548,11 @@ static bool invalid_llc_nr(struct mm_struct *mm, struct task_struct *p, if (scale == INT_MAX) return false; - return !fits_capacity((mm->sc_stat.nr_running_avg * cpu_smt_num_threads), + grp = READ_ONCE(mm->sched_cache_grp); + if (!grp) + return true; + + return !fits_capacity((READ_ONCE(grp->nr_running_avg) * cpu_smt_num_threads), (scale * per_cpu(sd_llc_size, cpu))); } @@ -1648,12 +1658,20 @@ static void account_llc_dequeue(struct rq *rq, struct task_struct *p) } } -void mm_init_sched(struct mm_struct *mm, - struct sched_cache_time __percpu *_pcpu_sched) +int mm_init_sched(struct mm_struct *mm, + struct sched_cache_time __percpu *_pcpu_sched) { + struct sched_cache_group *grp; unsigned long epoch = 0; int i; + grp = kzalloc_obj(*grp); + if (!grp) { + free_percpu(_pcpu_sched); + mm->sched_cache_grp = NULL; + return -ENOMEM; + } + for_each_possible_cpu(i) { struct sched_cache_time *pcpu_sched = per_cpu_ptr(_pcpu_sched, i); struct rq *rq = cpu_rq(i); @@ -1664,18 +1682,51 @@ void mm_init_sched(struct mm_struct *mm, epoch = rq->cpu_epoch; } - raw_spin_lock_init(&mm->sc_stat.lock); - mm->sc_stat.epoch = epoch; - mm->sc_stat.cpu = -1; - mm->sc_stat.next_scan = jiffies; - mm->sc_stat.nr_running_avg = 0; - mm->sc_stat.footprint = 0; + raw_spin_lock_init(&grp->lock); + grp->epoch = epoch; + grp->cpu = -1; + grp->next_scan = jiffies; + grp->nr_running_avg = 0; + grp->footprint = 0; + refcount_set(&grp->refcnt, 1); /* - * The update to mm->sc_stat should not be reordered - * before initialization to mm's other fields, in case + * The update to grp->pcpu_sched should not be reordered + * before initialization to grp's other fields, in case * the readers may get invalid mm_sched_epoch, etc. */ - smp_store_release(&mm->sc_stat.pcpu_sched, _pcpu_sched); + smp_store_release(&grp->pcpu_sched, _pcpu_sched); + /* + * Publish the group last. Not every reader qualifies it by + * grp->pcpu_sched - can_migrate_llc_task() only checks that the + * pointer is non-NULL before reading grp->footprint and + * grp->nr_running_avg - so a reachable group must already be + * fully initialized. + */ + smp_store_release(&mm->sched_cache_grp, grp); + return 0; +} + +static void sched_cache_group_free_rcu(struct rcu_head *rcu) +{ + struct sched_cache_group *grp = + container_of(rcu, struct sched_cache_group, rcu); + + free_percpu(grp->pcpu_sched); + kfree(grp); +} + +static void sched_cache_group_put(struct sched_cache_group *grp) +{ + if (!grp || !refcount_dec_and_test(&grp->refcnt)) + return; + + call_rcu(&grp->rcu, sched_cache_group_free_rcu); +} + +void mm_destroy_sched(struct mm_struct *mm) +{ + sched_cache_group_put(mm->sched_cache_grp); + mm->sched_cache_grp = NULL; } /* because why would C be fully specified */ @@ -1729,11 +1780,16 @@ static unsigned long fraction_mm_sched(struct rq *rq, static int get_pref_llc(struct task_struct *p, struct mm_struct *mm) { int mm_sched_llc = -1, mm_sched_cpu; + struct sched_cache_group *grp; if (!mm) return -1; - mm_sched_cpu = READ_ONCE(mm->sc_stat.cpu); + grp = READ_ONCE(mm->sched_cache_grp); + if (!grp) + return -1; + + mm_sched_cpu = READ_ONCE(grp->cpu); if (mm_sched_cpu != -1) { mm_sched_llc = llc_id(mm_sched_cpu); @@ -1764,6 +1820,7 @@ static inline void account_mm_sched(struct rq *rq, struct task_struct *p, s64 delta_exec) { struct sched_cache_time *pcpu_sched; + struct sched_cache_group *grp; struct mm_struct *mm = p->mm; int mm_sched_llc = -1; unsigned long epoch; @@ -1777,10 +1834,14 @@ void account_mm_sched(struct rq *rq, struct task_struct *p, s64 delta_exec) * init_task, kthreads and user thread created * by user_mode_thread() don't have mm. */ - if (!mm || !mm->sc_stat.pcpu_sched) + if (!mm) + return; + + grp = READ_ONCE(mm->sched_cache_grp); + if (!grp || !grp->pcpu_sched) return; - pcpu_sched = per_cpu_ptr(mm->sc_stat.pcpu_sched, cpu_of(rq)); + pcpu_sched = per_cpu_ptr(grp->pcpu_sched, cpu_of(rq)); scoped_guard (raw_spinlock, &rq->cpu_epoch_lock) { __update_mm_sched(rq, pcpu_sched); @@ -1793,11 +1854,11 @@ void account_mm_sched(struct rq *rq, struct task_struct *p, s64 delta_exec) * If this process hasn't hit task_cache_work() for a while invalidate * its preferred state. */ - if ((long)(epoch - READ_ONCE(mm->sc_stat.epoch)) > llc_epoch_affinity_timeout || + if ((long)(epoch - READ_ONCE(grp->epoch)) > llc_epoch_affinity_timeout || invalid_llc_nr(mm, p, cpu_of(rq)) || exceed_llc_capacity(mm, cpu_of(rq))) { - if (READ_ONCE(mm->sc_stat.cpu) != -1) - WRITE_ONCE(mm->sc_stat.cpu, -1); + if (READ_ONCE(grp->cpu) != -1) + WRITE_ONCE(grp->cpu, -1); } mm_sched_llc = get_pref_llc(p, mm); @@ -1814,30 +1875,35 @@ void account_mm_sched(struct rq *rq, struct task_struct *p, s64 delta_exec) static void task_tick_cache(struct rq *rq, struct task_struct *p) { struct callback_head *work = &p->cache_work; + struct sched_cache_group *grp; struct mm_struct *mm = p->mm; unsigned long epoch; if (!sched_cache_enabled()) return; - if (!mm || p->flags & PF_KTHREAD || - !mm->sc_stat.pcpu_sched) + if (!mm || p->flags & PF_KTHREAD) + return; + + grp = READ_ONCE(mm->sched_cache_grp); + if (!grp || !grp->pcpu_sched) return; epoch = rq->cpu_epoch; /* avoid moving backwards */ - if (time_after_eq(mm->sc_stat.epoch, epoch)) + if (time_after_eq(grp->epoch, epoch)) return; - guard(raw_spinlock)(&mm->sc_stat.lock); + guard(raw_spinlock)(&grp->lock); if (work->next == work) { task_work_add(p, work, TWA_RESUME); - WRITE_ONCE(mm->sc_stat.epoch, epoch); + WRITE_ONCE(grp->epoch, epoch); } } -static void get_scan_cpumasks(cpumask_var_t cpus, struct task_struct *p) +static void get_scan_cpumasks(cpumask_var_t cpus, struct task_struct *p, + struct sched_cache_group *grp) { #ifdef CONFIG_NUMA_BALANCING int cpu, curr_cpu, nid, pref_nid; @@ -1845,7 +1911,7 @@ static void get_scan_cpumasks(cpumask_var_t cpus, struct task_struct *p) if (!static_branch_likely(&sched_numa_balancing)) goto out; - cpu = READ_ONCE(p->mm->sc_stat.cpu); + cpu = READ_ONCE(grp->cpu); if (cpu != -1) nid = cpu_to_node(cpu); curr_cpu = task_cpu(p); @@ -1906,6 +1972,7 @@ static void task_cache_work(struct callback_head *work) unsigned long next_scan, now = jiffies; struct task_struct *p = current, *cur; unsigned long curr_m_a_occ = 0; + struct sched_cache_group *grp; struct mm_struct *mm = p->mm; unsigned long m_a_occ = 0; cpumask_var_t cpus; @@ -1917,12 +1984,16 @@ static void task_cache_work(struct callback_head *work) if (p->flags & PF_EXITING) return; - next_scan = READ_ONCE(mm->sc_stat.next_scan); + grp = READ_ONCE(mm->sched_cache_grp); + if (!grp) + return; + + next_scan = READ_ONCE(grp->next_scan); if (time_before(now, next_scan)) return; /* only 1 thread is allowed to scan */ - if (!try_cmpxchg(&mm->sc_stat.next_scan, &next_scan, + if (!try_cmpxchg(&grp->next_scan, &next_scan, now + max_t(unsigned long, READ_ONCE(llc_epoch_period), 1))) return; @@ -1930,8 +2001,8 @@ static void task_cache_work(struct callback_head *work) curr_cpu = task_cpu(p); if (invalid_llc_nr(mm, p, curr_cpu) || exceed_llc_capacity(mm, curr_cpu)) { - if (READ_ONCE(mm->sc_stat.cpu) != -1) - WRITE_ONCE(mm->sc_stat.cpu, -1); + if (READ_ONCE(grp->cpu) != -1) + WRITE_ONCE(grp->cpu, -1); return; } @@ -1942,7 +2013,7 @@ static void task_cache_work(struct callback_head *work) scoped_guard (cpus_read_lock) { guard(rcu)(); - get_scan_cpumasks(cpus, p); + get_scan_cpumasks(cpus, p, grp); for_each_cpu(cpu, cpus) { /* XXX sched_cluster_active */ @@ -1955,7 +2026,7 @@ static void task_cache_work(struct callback_head *work) for_each_cpu(i, sched_domain_span(sd)) { occ = fraction_mm_sched(cpu_rq(i), - per_cpu_ptr(mm->sc_stat.pcpu_sched, i)); + per_cpu_ptr(grp->pcpu_sched, i)); a_occ += occ; if (occ > m_occ) { m_occ = occ; @@ -1988,7 +2059,7 @@ static void task_cache_work(struct callback_head *work) m_a_cpu = m_cpu; } - if (llc_id(cpu) == llc_id(READ_ONCE(mm->sc_stat.cpu))) + if (llc_id(cpu) == llc_id(READ_ONCE(grp->cpu))) curr_m_a_occ = a_occ; cpumask_andnot(cpus, cpus, sched_domain_span(sd)); @@ -1997,7 +2068,7 @@ static void task_cache_work(struct callback_head *work) if (m_a_occ > (2 * curr_m_a_occ)) { /* - * Avoid switching sc_stat.cpu too fast. + * Avoid switching sched_cache_grp->cpu too fast. * The reason to choose 2X is because: * 1. It is better to keep the preferred LLC stable, * rather than changing it frequently and cause migrations @@ -2006,10 +2077,10 @@ static void task_cache_work(struct callback_head *work) * 3. 2X is chosen based on test results, as it delivers * the optimal performance gain so far. */ - WRITE_ONCE(mm->sc_stat.cpu, m_a_cpu); + WRITE_ONCE(grp->cpu, m_a_cpu); } - update_avg_scale(&mm->sc_stat.nr_running_avg, nr_running); + update_avg_scale(&grp->nr_running_avg, nr_running); free_cpumask_var(cpus); } @@ -3726,6 +3797,7 @@ static int preferred_group_nid(struct task_struct *p, int nid) static void task_numa_placement(struct task_struct *p) __context_unsafe(/* conditional locking */) { + struct sched_cache_group __maybe_unused *grp; int seq, nid, max_nid = NUMA_NO_NODE; unsigned long max_faults = 0; unsigned long fault_types[2] = { 0, 0 }; @@ -3818,19 +3890,23 @@ static void task_numa_placement(struct task_struct *p) * heuristic and occasional lost updates are tolerable. * * If a task exits, its corresponding footprint must - * be subtracted from the mm->sc_stat.footprint, otherwise - * the mm->sc_stat.footprint will not converge: - * the exiting thread's footprint remains unchanged/undecayed - * in mm->sc_stat.footprint. See exit_mm(). + * be subtracted from the mm->sched_cache_grp->footprint, + * otherwise the mm->sched_cache_grp->footprint will not + * converge: the exiting thread's footprint remains + * unchanged/undecayed in mm->sched_cache_grp->footprint. + * See exit_mm(). * * Lost updates and unsynchronized subtraction * in exit_mm() can cause footprint + diff to * go negative. Clamp to zero to prevent the * unsigned footprint from wrapping. */ - new_fp = (long)READ_ONCE(p->mm->sc_stat.footprint) + diff; - WRITE_ONCE(p->mm->sc_stat.footprint, - max(new_fp, 0L)); + grp = READ_ONCE(p->mm->sched_cache_grp); + if (!grp) + continue; + + new_fp = (long)READ_ONCE(grp->footprint) + diff; + WRITE_ONCE(grp->footprint, max(new_fp, 0L)); #endif } @@ -10778,6 +10854,7 @@ static inline bool task_misfits_asym_cpu(struct lb_env *env, struct task_struct static enum llc_mig can_migrate_llc_task(struct lb_env *env, struct task_struct *p) { + struct sched_cache_group *grp; struct mm_struct *mm; bool to_pref; int cpu, src_cpu, dst_cpu; @@ -10791,15 +10868,19 @@ static enum llc_mig can_migrate_llc_task(struct lb_env *env, if (!mm) return mig_unrestricted; - cpu = READ_ONCE(mm->sc_stat.cpu); + grp = READ_ONCE(mm->sched_cache_grp); + if (!grp) + return mig_unrestricted; + + cpu = READ_ONCE(grp->cpu); if (cpu < 0 || cpus_share_cache(src_cpu, dst_cpu)) return mig_unrestricted; /* skip cache aware load balance for too many threads */ if (invalid_llc_nr(mm, p, dst_cpu) || exceed_llc_capacity(mm, dst_cpu)) { - if (READ_ONCE(mm->sc_stat.cpu) != -1) - WRITE_ONCE(mm->sc_stat.cpu, -1); + if (READ_ONCE(grp->cpu) != -1) + WRITE_ONCE(grp->cpu, -1); return mig_unrestricted; } -- cgit v1.2.3 From b636fef85bda7d1bab9c0a45067ab1508d79d946 Mon Sep 17 00:00:00 2001 From: Tim Chen Date: Mon, 21 Sep 2026 17:37:25 -0700 Subject: sched/cache: Introduce task_struct->sched_cache_grp to fix UAF Add a sched_cache_grp pointer to task_struct so that scheduler code can access the cache group directly via the task, without going through mm->sched_cache_grp. This decouples the scheduler's hot-path accesses from the mm_struct. Each task holds its own refcount on the sched_cache_group, separate from the reference held by its mm_struct. The reference is acquired in copy_mm() (fork) and exec_mmap() (exec), and released in exit_mm(). This fixes the use-after-free when account_mm_sched() reaches the group through a task whose mm is being switched, as reported by Hyunwoo: https://lore.kernel.org/lkml/apPb-Dr4nPYuHQOK@v4bel/ Convert all scheduler code in fair.c and exit.c to use p->sched_cache_grp instead of p->mm->sched_cache_grp. Keep the fork/exec/exit reference management out of the generic mm paths: add sched_cache_fork(), sched_cache_fork_cleanup(), sched_cache_exec_mmap() and sched_cache_exit_mm() in kernel/sched/cache_sched.c (with empty stubs for !CONFIG_SCHED_CACHE), so fs/exec.c, kernel/fork.c and kernel/exit.c each call one helper instead of open-coding the refcounting under #ifdef. Also add sched_cache_group_get() and task_cache_group_get(). Fixes: df0d98475954 ("sched/cache: Introduce infrastructure for cache-aware load balancing") Closes: https://lore.kernel.org/lkml/apPb-Dr4nPYuHQOK@v4bel/ Closes: https://lore.kernel.org/all/343a7e07-7fad-4979-9c9b-82ec038c293c@linux.dev/ Reported-by: Hyunwoo Kim Reported-by: Zenghui Yu (Huawei) Co-developed-by: Chen Yu Signed-off-by: Chen Yu Signed-off-by: Tim Chen Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Ingo Molnar Cc: #7.2.x Link: https://patch.msgid.link/ae7081dc54736bf115215f9867abb2711a7403fb.1790035273.git.tim.c.chen@linux.intel.com --- kernel/exit.c | 33 +-------- kernel/fork.c | 2 + kernel/sched/fair.c | 196 ++++++++++++++++++++++++++++++++++++---------------- 3 files changed, 139 insertions(+), 92 deletions(-) (limited to 'kernel') diff --git a/kernel/exit.c b/kernel/exit.c index 024350e9b48c..282328d2b4cf 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -551,37 +551,6 @@ void mm_update_next_owner(struct mm_struct *mm) } #endif /* CONFIG_MEMCG */ -#if defined(CONFIG_SCHED_CACHE) && defined(CONFIG_NUMA_BALANCING) -/* - * Subtract the memory footprint of the current task from - * mm. - */ -static void exit_mm_sched_cache(struct mm_struct *mm) -{ - struct sched_cache_group *grp; - unsigned long fp, sub; - - if (!current->total_numa_faults) - return; - /* - * No lock protection due to performance considerations. - * Make sure the group footprint does not become - * negative. - */ - grp = READ_ONCE(mm->sched_cache_grp); - if (!grp) - return; - - fp = READ_ONCE(grp->footprint); - sub = min(fp, current->total_numa_faults); - WRITE_ONCE(grp->footprint, fp - sub); -} -#else -static inline void exit_mm_sched_cache(struct mm_struct *mm) -{ -} -#endif /* CONFIG_SCHED_CACHE CONFIG_NUMA_BALANCING */ - /* * Turn us into a lazy TLB process if we * aren't already.. @@ -594,7 +563,7 @@ static void exit_mm(void) if (!mm) return; - exit_mm_sched_cache(mm); + sched_cache_exit_mm(current); mmap_read_lock(mm); mmgrab_lazy_tlb(mm); diff --git a/kernel/fork.c b/kernel/fork.c index 5ef413368912..10f2d05d816a 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -1599,6 +1599,7 @@ static int copy_mm(u64 clone_flags, struct task_struct *tsk) tsk->mm = mm; tsk->active_mm = mm; + sched_cache_fork(tsk); return 0; } @@ -2602,6 +2603,7 @@ bad_fork_cleanup_io: bad_fork_cleanup_namespaces: exit_nsproxy_namespaces(p); bad_fork_cleanup_mm: + sched_cache_fork_cleanup(p); if (p->mm) { mm_clear_owner(p->mm, p); mmput(p->mm); diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index f0a9586332fd..974a7dfe3215 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -1478,7 +1478,7 @@ static inline int get_sched_cache_scale(int mul) return (1 + (tol - 1) * mul); } -static bool exceed_llc_capacity(struct mm_struct *mm, int cpu) +static bool exceed_llc_capacity(struct sched_cache_group *grp, int cpu) { #ifdef CONFIG_NUMA_BALANCING unsigned long llc, footprint; @@ -1492,11 +1492,6 @@ static bool exceed_llc_capacity(struct mm_struct *mm, int cpu) return true; if (static_branch_likely(&sched_numa_balancing)) { - struct sched_cache_group *grp = READ_ONCE(mm->sched_cache_grp); - - if (!grp) - return true; - /* * TBD: RDT exclusive LLC ways reserved should be * excluded. @@ -1531,10 +1526,9 @@ static bool exceed_llc_capacity(struct mm_struct *mm, int cpu) return false; } -static bool invalid_llc_nr(struct mm_struct *mm, struct task_struct *p, +static bool invalid_llc_nr(struct sched_cache_group *grp, struct task_struct *p, int cpu) { - struct sched_cache_group *grp; int scale; if (get_nr_threads(p) <= 1) @@ -1548,10 +1542,6 @@ static bool invalid_llc_nr(struct mm_struct *mm, struct task_struct *p, if (scale == INT_MAX) return false; - grp = READ_ONCE(mm->sched_cache_grp); - if (!grp) - return true; - return !fits_capacity((READ_ONCE(grp->nr_running_avg) * cpu_smt_num_threads), (scale * per_cpu(sd_llc_size, cpu))); } @@ -1723,6 +1713,96 @@ static void sched_cache_group_put(struct sched_cache_group *grp) call_rcu(&grp->rcu, sched_cache_group_free_rcu); } +DEFINE_FREE(sched_cache_group_put, struct sched_cache_group *, + sched_cache_group_put(_T)); + +#define rcu_deref_sched_cache_grp(tsk) \ + rcu_dereference_check((tsk)->sched_cache_grp, (tsk) == current) + +static struct sched_cache_group *sched_cache_replace_grp(struct task_struct *p, + struct sched_cache_group *new) +{ + struct sched_cache_group *old; + + old = rcu_deref_sched_cache_grp(p); + rcu_assign_pointer(p->sched_cache_grp, new); + + return old; +} + +struct sched_cache_group *sched_cache_group_get(struct sched_cache_group *grp) +{ + /* + * refcount_inc_not_zero() is the acquire primitive for lockless + * (RCU) lookups; plain refcount_inc() would scribble the count if + * it already reached zero. Return NULL in that case. + */ + if (grp && !refcount_inc_not_zero(&grp->refcnt)) + grp = NULL; + + return grp; +} + +struct sched_cache_group *task_cache_group_get(struct task_struct *p) +{ + guard(rcu)(); + return sched_cache_group_get(rcu_dereference(p->sched_cache_grp)); +} + +void sched_cache_fork(struct task_struct *p) +{ + /* + * The child takes its own reference on the mm's cache group, separate + * from the reference held by the mm. @p is not yet visible to readers, + * so a plain initializing store is enough. + */ + RCU_INIT_POINTER(p->sched_cache_grp, + sched_cache_group_get(p->mm->sched_cache_grp)); +} + +void sched_cache_fork_cleanup(struct task_struct *p) +{ + /* + * A fork that fails after sched_cache_fork() never reaches exit_mm(), + * so drop the reference here. @p never became visible, so there are no + * concurrent readers and the reference we hold keeps the group alive. + */ + sched_cache_group_put(rcu_access_pointer(p->sched_cache_grp)); + RCU_INIT_POINTER(p->sched_cache_grp, NULL); +} + +void sched_cache_exec_mmap(struct task_struct *p, struct mm_struct *mm) +{ + struct sched_cache_group *old; + + /* + * Acquire the new reference before publishing the pointer, then drop + * the old one. @p is current and the only writer of its own pointer. + */ + old = sched_cache_replace_grp(p, sched_cache_group_get(mm->sched_cache_grp)); + sched_cache_group_put(old); +} + +void sched_cache_exit_mm(struct task_struct *p) +{ + struct sched_cache_group *grp = sched_cache_replace_grp(p, NULL); + +#ifdef CONFIG_NUMA_BALANCING + /* + * Subtract this task's footprint from the group before dropping the + * reference, so the group footprint converges as its threads exit. + * Unlocked for performance; clamp to avoid underflow. + */ + if (grp && p->total_numa_faults) { + unsigned long fp = READ_ONCE(grp->footprint); + unsigned long sub = min(fp, p->total_numa_faults); + + WRITE_ONCE(grp->footprint, fp - sub); + } +#endif + sched_cache_group_put(grp); +} + void mm_destroy_sched(struct mm_struct *mm) { sched_cache_group_put(mm->sched_cache_grp); @@ -1777,15 +1857,10 @@ static unsigned long fraction_mm_sched(struct rq *rq, return div64_u64(NICE_0_LOAD * pcpu_sched->runtime, rq->cpu_runtime + 1); } -static int get_pref_llc(struct task_struct *p, struct mm_struct *mm) +static int get_pref_llc(struct task_struct *p, struct sched_cache_group *grp) { int mm_sched_llc = -1, mm_sched_cpu; - struct sched_cache_group *grp; - if (!mm) - return -1; - - grp = READ_ONCE(mm->sched_cache_grp); if (!grp) return -1; @@ -1819,9 +1894,8 @@ static unsigned int task_running_on_cpu(int cpu, struct task_struct *p); static inline void account_mm_sched(struct rq *rq, struct task_struct *p, s64 delta_exec) { + struct sched_cache_group *grp = rcu_dereference_all(p->sched_cache_grp); struct sched_cache_time *pcpu_sched; - struct sched_cache_group *grp; - struct mm_struct *mm = p->mm; int mm_sched_llc = -1; unsigned long epoch; @@ -1832,12 +1906,8 @@ void account_mm_sched(struct rq *rq, struct task_struct *p, s64 delta_exec) return; /* * init_task, kthreads and user thread created - * by user_mode_thread() don't have mm. + * by user_mode_thread() don't have a cache group. */ - if (!mm) - return; - - grp = READ_ONCE(mm->sched_cache_grp); if (!grp || !grp->pcpu_sched) return; @@ -1855,13 +1925,13 @@ void account_mm_sched(struct rq *rq, struct task_struct *p, s64 delta_exec) * its preferred state. */ if ((long)(epoch - READ_ONCE(grp->epoch)) > llc_epoch_affinity_timeout || - invalid_llc_nr(mm, p, cpu_of(rq)) || - exceed_llc_capacity(mm, cpu_of(rq))) { + invalid_llc_nr(grp, p, cpu_of(rq)) || + exceed_llc_capacity(grp, cpu_of(rq))) { if (READ_ONCE(grp->cpu) != -1) WRITE_ONCE(grp->cpu, -1); } - mm_sched_llc = get_pref_llc(p, mm); + mm_sched_llc = get_pref_llc(p, grp); /* task not on rq accounted later in account_entity_enqueue() */ if (task_running_on_cpu(rq->cpu, p) && @@ -1874,19 +1944,15 @@ void account_mm_sched(struct rq *rq, struct task_struct *p, s64 delta_exec) static void task_tick_cache(struct rq *rq, struct task_struct *p) { + struct sched_cache_group *grp = rcu_dereference_all(p->sched_cache_grp); struct callback_head *work = &p->cache_work; - struct sched_cache_group *grp; - struct mm_struct *mm = p->mm; unsigned long epoch; if (!sched_cache_enabled()) return; - if (!mm || p->flags & PF_KTHREAD) - return; - - grp = READ_ONCE(mm->sched_cache_grp); - if (!grp || !grp->pcpu_sched) + if (!grp || p->flags & PF_KTHREAD || + !grp->pcpu_sched) return; epoch = rq->cpu_epoch; @@ -1968,14 +2034,13 @@ static inline void update_avg_scale(u64 *avg, u64 sample) static void task_cache_work(struct callback_head *work) { + struct sched_cache_group *grp __free(sched_cache_group_put) = NULL; + cpumask_var_t cpus __free(free_cpumask_var) = CPUMASK_VAR_NULL; int cpu, m_a_cpu = -1, nr_running = 0, curr_cpu; unsigned long next_scan, now = jiffies; struct task_struct *p = current, *cur; unsigned long curr_m_a_occ = 0; - struct sched_cache_group *grp; - struct mm_struct *mm = p->mm; unsigned long m_a_occ = 0; - cpumask_var_t cpus; WARN_ON_ONCE(work != &p->cache_work); @@ -1984,7 +2049,12 @@ static void task_cache_work(struct callback_head *work) if (p->flags & PF_EXITING) return; - grp = READ_ONCE(mm->sched_cache_grp); + /* + * A reference makes sure grp is not released by others. The rcu + * lock can not be held till after zalloc_cpumask_var() below, + * because the latter might sleep. + */ + grp = task_cache_group_get(p); if (!grp) return; @@ -1999,8 +2069,8 @@ static void task_cache_work(struct callback_head *work) return; curr_cpu = task_cpu(p); - if (invalid_llc_nr(mm, p, curr_cpu) || - exceed_llc_capacity(mm, curr_cpu)) { + if (invalid_llc_nr(grp, p, curr_cpu) || + exceed_llc_capacity(grp, curr_cpu)) { if (READ_ONCE(grp->cpu) != -1) WRITE_ONCE(grp->cpu, -1); @@ -2033,9 +2103,13 @@ static void task_cache_work(struct callback_head *work) m_cpu = i; } + /* + * rcu_access_pointer() is used because the + * pointer is only compared, never dereferenced. + */ cur = rcu_dereference_all(cpu_rq(i)->curr); if (cur && !(cur->flags & (PF_EXITING | PF_KTHREAD)) && - cur->mm == mm) + rcu_access_pointer(cur->sched_cache_grp) == grp) nr_running++; } @@ -2081,7 +2155,6 @@ static void task_cache_work(struct callback_head *work) } update_avg_scale(&grp->nr_running_avg, nr_running); - free_cpumask_var(cpus); } void init_sched_mm(struct task_struct *p) @@ -2090,6 +2163,13 @@ void init_sched_mm(struct task_struct *p) init_task_work(work, task_cache_work); work->next = work; + /* + * dup_task_struct() copies the parent's task_struct, including its + * sched_cache_grp, for which the child holds no reference. Clear it + * here - before copy_mm() runs - so the child never carries a + * borrowed pointer that the fork error path would put. + */ + RCU_INIT_POINTER(p->sched_cache_grp, NULL); /* * Reset new task's preference to avoid * polluting account_llc_enqueue(). @@ -3890,10 +3970,9 @@ static void task_numa_placement(struct task_struct *p) * heuristic and occasional lost updates are tolerable. * * If a task exits, its corresponding footprint must - * be subtracted from the mm->sched_cache_grp->footprint, - * otherwise the mm->sched_cache_grp->footprint will not - * converge: the exiting thread's footprint remains - * unchanged/undecayed in mm->sched_cache_grp->footprint. + * be subtracted from p->sched_cache_grp->footprint, + * otherwise the footprint will not converge: the + * exiting thread's footprint remains unchanged/undecayed. * See exit_mm(). * * Lost updates and unsynchronized subtraction @@ -3901,12 +3980,14 @@ static void task_numa_placement(struct task_struct *p) * go negative. Clamp to zero to prevent the * unsigned footprint from wrapping. */ - grp = READ_ONCE(p->mm->sched_cache_grp); - if (!grp) - continue; + scoped_guard(rcu) { + grp = rcu_dereference(p->sched_cache_grp); - new_fp = (long)READ_ONCE(grp->footprint) + diff; - WRITE_ONCE(grp->footprint, max(new_fp, 0L)); + if (grp) { + new_fp = (long)READ_ONCE(grp->footprint) + diff; + WRITE_ONCE(grp->footprint, max(new_fp, 0L)); + } + } #endif } @@ -10855,7 +10936,6 @@ static enum llc_mig can_migrate_llc_task(struct lb_env *env, struct task_struct *p) { struct sched_cache_group *grp; - struct mm_struct *mm; bool to_pref; int cpu, src_cpu, dst_cpu; @@ -10864,11 +10944,7 @@ static enum llc_mig can_migrate_llc_task(struct lb_env *env, src_cpu = env->src_cpu; dst_cpu = env->dst_cpu; - mm = p->mm; - if (!mm) - return mig_unrestricted; - - grp = READ_ONCE(mm->sched_cache_grp); + grp = rcu_dereference_all(p->sched_cache_grp); if (!grp) return mig_unrestricted; @@ -10877,8 +10953,8 @@ static enum llc_mig can_migrate_llc_task(struct lb_env *env, return mig_unrestricted; /* skip cache aware load balance for too many threads */ - if (invalid_llc_nr(mm, p, dst_cpu) || - exceed_llc_capacity(mm, dst_cpu)) { + if (invalid_llc_nr(grp, p, dst_cpu) || + exceed_llc_capacity(grp, dst_cpu)) { if (READ_ONCE(grp->cpu) != -1) WRITE_ONCE(grp->cpu, -1); return mig_unrestricted; -- cgit v1.2.3 From 65efcccddc83d6a19e8a2e2a6117811e39e589bf Mon Sep 17 00:00:00 2001 From: Chen Yu Date: Mon, 21 Sep 2026 17:37:26 -0700 Subject: sched/cache: Skip kernel threads for cache aware scheduling to rubustify the code Kernel thread should not be covered by cache aware scheduling as it borrows the statistics from the user space thread. Filter the kernel thread in account_mm_sched(). In theory a kernel thread does not have any valid cache group, so !grp should gate the kernel thread. Add the PF_KTHREAD check explicitly here for safety reasons, to guard against future modifications and to pair with task_tick_cache(). Fixes: df0d98475954 ("sched/cache: Introduce infrastructure for cache-aware load balancing") Signed-off-by: Chen Yu Signed-off-by: Tim Chen Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Ingo Molnar Cc: # 7.2.x Link: https://patch.msgid.link/058f0c6ea7b991c177a17de347fa3157f25489a7.1790035273.git.tim.c.chen@linux.intel.com --- kernel/sched/fair.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) (limited to 'kernel') diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 974a7dfe3215..57360f5cdde4 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -1907,8 +1907,14 @@ void account_mm_sched(struct rq *rq, struct task_struct *p, s64 delta_exec) /* * init_task, kthreads and user thread created * by user_mode_thread() don't have a cache group. - */ - if (!grp || !grp->pcpu_sched) + * In theory a kernel thread does not have any valid + * cache group, because sched_cache_fork() is not + * invoked for a kernel thread - !grp should gate the + * kernel thread. Use the PF_KTHREAD check explicitly + * here for safety reasons, to guard against future + * modifications and to pair with task_tick_cache(). + */ + if (p->flags & PF_KTHREAD || !grp || !grp->pcpu_sched) return; pcpu_sched = per_cpu_ptr(grp->pcpu_sched, cpu_of(rq)); -- cgit v1.2.3 From 3cb0243767fd033bdce95f4f1b5882172a2f8119 Mon Sep 17 00:00:00 2001 From: Davi Chaves Azevedo Date: Mon, 21 Sep 2026 17:37:27 -0700 Subject: sched/cache: Refresh LLC capacity across CPU hotplug, to fix capacity underestimation bug The scheduler scales LLC capacity by the fraction of cache-sharing CPUs covered by a domain: llc_bytes = cache_size * span_weight / shared_weight During CPU teardown, sched_cpu_deactivate() rebuilds scheduler domains before cacheinfo_cpu_pre_down() removes the CPU from shared_cpu_map. The new domains therefore use the old sharing weight. The later call to sched_update_llc_bytes() looks up the departing CPU's sd_llc, which has already been detached, and returns without correcting the surviving CPUs. On a Ryzen 5 7535U with twelve logical CPUs sharing a 16 MiB LLC, offlining one SMT sibling left the remaining CPUs with: llc_bytes = floor(16777216 * 11 / 12) = 15379114 bytes The correct capacity is still 16777216 bytes. On systems with active cache-aware scheduling, an underestimated capacity can cause exceed_llc_capacity() to reject aggregation for a process whose footprint would fit. Unchanged cpuset partitions sharing the physical cache can also retain stale capacity when a CPU comes online in another partition. Pass the cache-sharing mask already retained by cacheinfo to the scheduler update. Refresh every surviving CPU using its own LLC domain so that each partition receives the correct share. This also preserves the correction needed as cache-sharing maps grow during boot. Keep the existing CPU-hotplug and scheduler-domain synchronization. The update remains on the hotplug path; no steady-state scheduling operation or persistent allocation is added. Fixes: 7030513a0877 ("sched/cache: Calculate the LLC size and store it in sched_domain") Signed-off-by: Davi Chaves Azevedo Signed-off-by: Tim Chen Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Ingo Molnar Reviewed-by: Chen Yu Reviewed-by: Tim Chen Reviewed-by: K Prateek Nayak Tested-by: Chen Yu Tested-by: K Prateek Nayak Cc: # v7.2.x Link: https://patch.msgid.link/6751d93e15889e624796c74db0bfe66603d60b1b.1790035273.git.tim.c.chen@linux.intel.com --- kernel/sched/topology.c | 22 +++++++++++++--------- 1 file changed, 13 insertions(+), 9 deletions(-) (limited to 'kernel') diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c index 0248227d983a..3dab0253976f 100644 --- a/kernel/sched/topology.c +++ b/kernel/sched/topology.c @@ -985,8 +985,8 @@ void sched_cache_active_set(void) } /* - * Update the bottom sched_domain's llc_bytes for @cpu and all its - * LLC siblings. Called from cacheinfo_cpu_online() or + * Update the bottom sched_domain's llc_bytes for @cpus sharing a physical + * LLC. Called from cacheinfo_cpu_online() or * cacheinfo_cpu_pre_down() with cpu hotplug lock held. * * Note: get_effective_llc_bytes() returns 0 on PowerPC. @@ -996,17 +996,13 @@ void sched_cache_active_set(void) * and does not populates the per-CPU struct cpu_cacheinfo array * that get_cpu_cacheinfo_llc() reads. */ -void sched_update_llc_bytes(unsigned int cpu) +void sched_update_llc_bytes(const struct cpumask *cpus) { struct sched_domain *sd, *sdp; unsigned int i; sched_domains_mutex_lock(); - sdp = rcu_dereference_sched_domain(per_cpu(sd_llc, cpu)); - if (!sdp) - goto unlock; - /* * ci->shared_cpu_map is built incrementally as CPUs come * online, so the first CPU in an LLC initially sees @@ -1014,14 +1010,22 @@ void sched_update_llc_bytes(unsigned int cpu) * get_effective_llc_bytes(). Re-evaluating every LLC * sibling on each online event corrects this once the full * shared_cpu_map is known. + * + * The departing CPU's domains have already been detached when + * cacheinfo removes it. Use the surviving cache siblings instead. + * They may belong to different cpuset partitions, so use each CPU's + * own LLC domain to scale its share of the physical cache. */ - for_each_cpu(i, sched_domain_span(sdp)) { + for_each_cpu(i, cpus) { + sdp = rcu_dereference_sched_domain(per_cpu(sd_llc, i)); + if (!sdp) + continue; + sd = rcu_dereference_sched_domain(cpu_rq(i)->sd); if (sd) sd->llc_bytes = get_effective_llc_bytes(i, sdp); } -unlock: sched_domains_mutex_unlock(); } -- cgit v1.2.3 From 41112a787f9182c7f2d27122817861e3f22ef928 Mon Sep 17 00:00:00 2001 From: Florian Schmaus Date: Sun, 20 Sep 2026 16:35:25 +0200 Subject: PM: hibernate: Freeze kernel threads after image preallocation Commit 783c81098445 ("PM: hibernate: call preallocate_image() after freeze prepare") moved hibernate_preallocate_memory() after dpm_prepare() so that device drivers have the opportunity to release pinned/unswappable memory during their ->prepare() callback before memory is preallocated for the snapshot image. However, that commit also placed hibernate_preallocate_memory() after freeze_kernel_threads(). While it was assumed during review that swap I/O submitted via submit_bio() is synchronous and would not depend on frozen kernel threads, this does not hold in practice. Calling hibernate_preallocate_memory() with kernel threads frozen leads to intermittent deadlocks during hibernation. Inside hibernate_preallocate_memory(), shrink_all_memory() is invoked with .may_writepage = 1 and .may_swap = 1 to aggressively reclaim and swap out pages. Any writeback or swap I/O that relies on freezable kernel threads, block device helpers, or WQ_FREEZABLE workqueues (such as those in storage drivers, device mapper, or filesystems) deadlocks waiting on tasks that are stuck in the refrigerator. Fix this by reordering hibernation_snapshot(): 1. Call dpm_prepare(PMSG_FREEZE) first, allowing device drivers to release pinned resources while kernel threads are still active. 2. Call hibernate_preallocate_memory() second, performing page reclaim and swapout while storage layers, workqueues, and kernel threads are alive. 3. Call freeze_kernel_threads() third, only after all memory preallocation and swap I/O have completed. Additionally, restore the call to swsusp_free() in the cleanup path so that preallocated image memory is properly freed if freeze_kernel_threads() fails or if TEST_FREEZER is enabled. Fixes: 783c81098445 ("PM: hibernate: call preallocate_image() after freeze prepare") Signed-off-by: Florian Schmaus Reviewed-by: Mario Limonciello (AMD) Tested-by: Matthew Leach Reviewed-by: Matthew Leach Link: https://patch.msgid.link/20260920-fix-hibernation-v1-1-f9940c2d7d7f@geekplace.eu Signed-off-by: Rafael J. Wysocki --- kernel/power/hibernate.c | 26 ++++++++++++++------------ 1 file changed, 14 insertions(+), 12 deletions(-) (limited to 'kernel') diff --git a/kernel/power/hibernate.c b/kernel/power/hibernate.c index d2479c69d71a..c13f68ab7f6e 100644 --- a/kernel/power/hibernate.c +++ b/kernel/power/hibernate.c @@ -408,9 +408,18 @@ int hibernation_snapshot(int platform_mode) if (error) goto Close; + error = dpm_prepare(PMSG_FREEZE); + if (error) + goto Complete; + + /* Preallocate image memory before freezing kernel threads and shutting down devices. */ + error = hibernate_preallocate_memory(); + if (error) + goto Complete; + error = freeze_kernel_threads(); if (error) - goto Close; + goto Cleanup; if (hibernation_test(TEST_FREEZER)) { @@ -422,15 +431,6 @@ int hibernation_snapshot(int platform_mode) goto Thaw; } - error = dpm_prepare(PMSG_FREEZE); - if (error) - goto Complete; - - /* Preallocate image memory before shutting down devices. */ - error = hibernate_preallocate_memory(); - if (error) - goto Complete; - console_suspend_all(); pm_restrict_gfp_mask(); @@ -464,10 +464,12 @@ int hibernation_snapshot(int platform_mode) platform_end(platform_mode); return error; - Complete: - dpm_complete(PMSG_RECOVER); Thaw: thaw_kernel_threads(); + Cleanup: + swsusp_free(); + Complete: + dpm_complete(PMSG_RECOVER); goto Close; } -- cgit v1.2.3 From a6c1edfbe240e4377038a0e1d233ad81fde9a21b Mon Sep 17 00:00:00 2001 From: Emil Tsalapatis Date: Tue, 22 Sep 2026 17:20:22 +0000 Subject: bpf: Reject pkt arguments in mutating subprogs The verifier tracks changes in how PTR_TO_PACKET registers' bounds are modified across subprog boundaries. PTR_TO_PACKET registers are actually passed as PTR_TO_MEM, which is assumed valid for the entire call. This is not the case with packet memory, where a pskb_* call may invalidate its memory region. Reject BPF code that passes PTR_TO_PACKET pointers to subprogs that may mutate a packet. We cannot pass the pointer as a true PTR_TO_PACKET because we would also need to somehow pass the PTR_TO_PACKET_META or PTR_TO_PACKET_END to the subprog. Since we cannot avoid representing the pointer in the subprog as PTR_TO_MEM, only permit it if the subprog is guaranteed not to mutate the packet. Fixes: 80f281664f5a ("bpf: Support pointers in global func args") Reported-by: Nicholas Carlini Suggested-by: Nicholas Carlini Signed-off-by: Emil Tsalapatis Signed-off-by: Alexei Starovoitov Link: https://patch.msgid.link/20260922172028.6269-6-emil@etsalapatis.com --- kernel/bpf/verifier.c | 10 ++++++++++ 1 file changed, 10 insertions(+) (limited to 'kernel') diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index dd8bb179d39e..7ffbb804184f 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -9750,6 +9750,16 @@ static int btf_check_func_arg_match(struct bpf_verifier_env *env, int subprog, if (check_mem_reg(env, reg, argno, arg->mem_size, BPF_READ | BPF_WRITE, NULL, NULL)) return -EINVAL; + /* + * PTR_TO_PACKET get passed as PTR_TO_MEM, preventing + * us from adjusting bounds tracking info. + */ + if ((reg_is_pkt_pointer_any(reg) || reg_is_dynptr_slice_pkt(reg)) && + sub->changes_pkt_data) { + bpf_log(log, "%s is a packet pointer, but func#%d may change packet data\n", + reg_arg_name(env, argno), subprog); + return -EINVAL; + } if (!(arg->arg_type & PTR_MAYBE_NULL) && (type_may_be_null(reg->type) || bpf_register_is_null(reg))) { bpf_log(log, "%s is expected to be non-NULL\n", -- cgit v1.2.3 From f85f5917aa2fbd861c72ea71ecb14a2fa915c3f6 Mon Sep 17 00:00:00 2001 From: Emil Tsalapatis Date: Tue, 22 Sep 2026 17:20:24 +0000 Subject: bpf: Prevent variable arena/non-arena register contents The verifier marks ALU instructions that include at least one arena operand with needs_zext: These instructions are fixed up after verification to be ALU32 instructions to ensure that the result is a valid offset into an arena. However, different code paths may provide two non-arena 64-bit arguments to the same instruction. The result of the operation in that code path is wrong, since it is now unexpectedly truncated to 32 bits and zero-extended. Add logic to the verifier to ensure every instruction either always has at least one PTR_TO_ARENA argument, or never does. Since needs_zext already tracks the first scenario, add a prevent_zext field in bpf_insn_aux to track the latter. Reject instructions that use arena arguments and have prevent_zext set, or do not have arena arguments and have needs_zext set. Fixes: 6082b6c328b5 ("bpf: Recognize addr_space_cast instruction in the verifier.") Reported-by: Nicholas Carlini Suggested-by: Nicholas Carlini Signed-off-by: Emil Tsalapatis Signed-off-by: Alexei Starovoitov Link: https://patch.msgid.link/20260922172028.6269-8-emil@etsalapatis.com --- kernel/bpf/verifier.c | 24 +++++++++++++++++++++++- 1 file changed, 23 insertions(+), 1 deletion(-) (limited to 'kernel') diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 7ffbb804184f..41b49c56e123 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -15741,6 +15741,7 @@ static int adjust_reg_min_max_vals(struct bpf_verifier_env *env, struct bpf_reg_state *regs = state->regs, *dst_reg, *src_reg; struct bpf_reg_state *ptr_reg = NULL, off_reg = {0}; bool alu32 = (BPF_CLASS(insn->code) != BPF_ALU64); + struct bpf_insn_aux_data *aux = cur_aux(env); u8 opcode = BPF_OP(insn->code); int err; @@ -15752,12 +15753,23 @@ static int adjust_reg_min_max_vals(struct bpf_verifier_env *env, /* Case where at least one operand is an arena. */ if (dst_reg->type == PTR_TO_ARENA || (src_reg && src_reg->type == PTR_TO_ARENA)) { - struct bpf_insn_aux_data *aux = cur_aux(env); if (dst_reg->type != PTR_TO_ARENA) *dst_reg = *src_reg; if (BPF_CLASS(insn->code) == BPF_ALU64) { + /* + * Only arena pointers set needs_zext, but doing so + * modifies the instruction at fixup time to an ALU32 + * and makes it unsuitable for 64-bit scalar args. We + * prevent zext from being set if the instruction has + * been previously called with non-arena registers. + */ + if (aux->prevent_zext) { + verbose(env, "same insn cannot be used with and without arena pointer\n"); + return -EINVAL; + } + /* * 32-bit operations zero upper bits automatically. * 64-bit operations need to be converted to 32. @@ -15770,6 +15782,16 @@ static int adjust_reg_min_max_vals(struct bpf_verifier_env *env, return 0; } + /* Prevent the instruction from being used with arena pointers (see above). */ + if (env->prog->aux->arena && BPF_CLASS(insn->code) == BPF_ALU64) { + if (aux->needs_zext) { + verbose(env, "same insn cannot be used with and without arena pointer\n"); + return -EINVAL; + } + + aux->prevent_zext = true; + } + if (dst_reg->type != SCALAR_VALUE) ptr_reg = dst_reg; -- cgit v1.2.3 From 6db1ce73e9853f533eb7f413f14ba00f8ec6f80d Mon Sep 17 00:00:00 2001 From: Weiming Shi Date: Sun, 20 Sep 2026 21:23:04 +0800 Subject: bpf: Reject dev-bound-only programs on other devices __bpf_offload_dev_match() falls back to comparing offdev pointers after an exact netdev mismatch. Bound-only programs normally have NULL offdevs, so unrelated netdevs compare equal. A bound-only program on an offload-registered netdev can instead inherit a real offdev and match a sibling port. With CAP_BPF and CAP_NET_ADMIN, a caller can use bpf(BPF_LINK_CREATE) with a different target ifindex to run metadata kfuncs specialized for the bound driver on the target driver's xdp_buff. Running a veth-bound program on tun reads beyond tun's bare stack xdp_buff as a veth_xdp_buff. Oops: general protection fault, probably for non-canonical address KASAN: null-ptr-deref in range [0x0000000000000010-0x0000000000000017] RIP: 0010:veth_xdp_rx_timestamp (drivers/net/veth.c:1673) Call Trace: ... tun_build_skb (drivers/net/tun.c:1739) tun_get_user (drivers/net/tun.c:1856) tun_chr_write_iter (drivers/net/tun.c:2091) vfs_write (fs/read_write.c:595 fs/read_write.c:687) ksys_write (fs/read_write.c:739) do_syscall_64 (arch/x86/entry/syscall_64.c:84) entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:121) Kernel panic - not syncing: Fatal exception in interrupt Restrict non-offloaded programs to exact netdev matches and retain the shared-offdev fallback only for genuinely offloaded multi-port programs. Fixes: 2b3486bc2d23 ("bpf: Introduce device-bound XDP programs") Reported-by: Signed-off-by: Weiming Shi Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/20260917161335.1020405-2-bestswngs@gmail.com/ Link: https://patch.msgid.link/20260920132303.4109240-3-bestswngs@gmail.com --- kernel/bpf/offload.c | 2 ++ 1 file changed, 2 insertions(+) (limited to 'kernel') diff --git a/kernel/bpf/offload.c b/kernel/bpf/offload.c index 0d6f5569588c..d855399812ee 100644 --- a/kernel/bpf/offload.c +++ b/kernel/bpf/offload.c @@ -698,6 +698,8 @@ static bool __bpf_offload_dev_match(struct bpf_prog *prog, return false; if (offload->netdev == netdev) return true; + if (!bpf_prog_is_offloaded(prog->aux)) + return false; ondev1 = bpf_offload_find_netdev(offload->netdev); ondev2 = bpf_offload_find_netdev(netdev); -- cgit v1.2.3 From cca4980630b3c7a85f53cb43c6018184ce5d4e37 Mon Sep 17 00:00:00 2001 From: Namhyung Kim Date: Sun, 20 Sep 2026 16:16:39 -0700 Subject: perf/core: Fix a refcount leak in attach_perf_ctx_data() The attach_perf_ctx_data() can race on global and !global cases. The global case is protected by global_ctx_data_rwsem and shares a single reference count using perf_ctx_data.global field. But when it races with !global case, it may miss to set the global field and result in a reference count leak. CPU1 CPU2 ---------------------------------------------------------------- attach_task_ctx_data(.global=1) attach_task_ctx_data(.global=0) cd1 = alloc_perf_ctx_data(); cd2 = alloc_perf_ctx_data(); // { .global = 0, .refcount = 1 }; try_cmpxchg(); // success, // task->perf_ctx_data = cd2 try_cmpxhg(); // fail; old = cd2 refcount_inc_not_zero(&old->refcount); // success // old.refcount = 2 free_perf_ctx_data(cd1); Then later detach_global_ctx_data() will see the data but it's not marked as global, so it won't call detach_task_ctx_data(). Fixes: 506e64e710ff ("perf: attach/detach PMU specific data") Assisted-by: Sashiko.dev:Gemini-3.1-pro Signed-off-by: Namhyung Kim Signed-off-by: Peter Zijlstra (Intel) Link: https://patch.msgid.link/20260920231639.11910-1-namhyung@kernel.org --- kernel/events/core.c | 2 ++ 1 file changed, 2 insertions(+) (limited to 'kernel') diff --git a/kernel/events/core.c b/kernel/events/core.c index db7b76d6b68a..e180134bad5e 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -5454,6 +5454,8 @@ attach_task_ctx_data(struct task_struct *task, struct kmem_cache *ctx_cache, } if (refcount_inc_not_zero(&old->refcount)) { + if (global) + old->global = true; free_perf_ctx_data(cd); /* unused */ return 0; } -- cgit v1.2.3 From 36bb85cf36cab15fb611cb44b78a5df06e4e69a2 Mon Sep 17 00:00:00 2001 From: Puranjay Mohan Date: Mon, 10 Aug 2026 06:35:34 -0700 Subject: perf/core: Fix NULL pmu_ctx passed to pmu->sched_task() perf_pmu_sched_task() returns early when cpuctx->task_ctx is set, and cpc->task_epc is only non-NULL while a task context is scheduled in on this CPU. __perf_pmu_sched_task() therefore always passes NULL: Unable to handle kernel NULL pointer dereference at virtual address 00 pc : armv8pmu_sched_task+0x14/0x50 Call trace: armv8pmu_sched_task+0x14/0x50 (P) perf_pmu_sched_task+0xac/0x108 __perf_event_task_sched_out+0x6c/0xe0 Pass &cpc->epc instead, the CPU-wide context for this PMU, which the function already dereferences a few lines up to find pmu. armv8pmu_sched_task() is the only in-tree implementation that dereferences the argument, and it only reads ->pmu, so the oops needs BRBE, added in v6.17. Fixes: bd2756811766 ("perf: Rewrite core context handling") Signed-off-by: Puranjay Mohan Signed-off-by: Peter Zijlstra (Intel) Tested-by: Yifan Wu Cc: stable@vger.kernel.org Link: https://patch.msgid.link/20260810133540.1947118-2-puranjay@kernel.org --- kernel/events/core.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'kernel') diff --git a/kernel/events/core.c b/kernel/events/core.c index e180134bad5e..7ce72f366f6c 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -3914,7 +3914,7 @@ static void __perf_pmu_sched_task(struct perf_cpu_pmu_context *cpc, perf_ctx_lock(cpuctx, cpuctx->task_ctx); perf_pmu_disable(pmu); - pmu->sched_task(cpc->task_epc, task, sched_in); + pmu->sched_task(&cpc->epc, task, sched_in); perf_pmu_enable(pmu); perf_ctx_unlock(cpuctx, cpuctx->task_ctx); -- cgit v1.2.3 From 3d8d74100954a3b17e5c5e37adfe14e16b1db103 Mon Sep 17 00:00:00 2001 From: Puranjay Mohan Date: Mon, 10 Aug 2026 06:35:35 -0700 Subject: perf/core: Run sched_task() for PMUs with only CPU-wide events perf_pmu_sched_task() returns early when cpuctx->task_ctx is set and leaves the work to perf_ctx_sched_task_cb(), which only walks ctx->pmu_ctx_list. A PMU whose events are all CPU-wide is not on that list, so nothing calls its sched_task(). With perf record -b -e cycles -a -- ls armv8pmu_sched_task() is skipped on every switch to a task that has a perf context but no event on that PMU, and BRBE records leak across the task boundary. intel_pmu_lbr_add() calls perf_sched_cb_inc() unconditionally too, so LBR records leak the same way on x86. Drop the early return and skip only the CPCs that perf_ctx_sched_task_cb() handles. That one needs a gate of its own to make the split exact: it tests cpc->sched_cb_usage, which perf_sched_cb_inc() sets per CPU for every branch stack user, so a task with an event for that PMU pinned to another CPU would be handled twice. On x86 the second __intel_pmu_lbr_restore() finds lbr_stack_state == LBR_NONE and calls intel_pmu_lbr_reset(), throwing away the callstack the first one restored. cpc->task_epc is set only while a task context is scheduled in, and there is one epc per PMU on ctx->pmu_ctx_list, so the two gates are inverses. For the CPCs perf_pmu_sched_task() picks up, the callback now runs outside the perf_ctx_disable() and perf_ctx_enable() pair in perf_event_context_sched_in(). __perf_pmu_sched_task() disables the PMU around the call itself. Fixes: bd2756811766 ("perf: Rewrite core context handling") Signed-off-by: Puranjay Mohan Signed-off-by: Peter Zijlstra (Intel) Tested-by: Yifan Wu Link: https://patch.msgid.link/20260810133540.1947118-3-puranjay@kernel.org Cc: stable@vger.kernel.org --- kernel/events/core.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-) (limited to 'kernel') diff --git a/kernel/events/core.c b/kernel/events/core.c index 7ce72f366f6c..634d2ccbab82 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -3764,6 +3764,9 @@ static void perf_ctx_sched_task_cb(struct perf_event_context *ctx, list_for_each_entry(pmu_ctx, &ctx->pmu_ctx_list, pmu_ctx_entry) { cpc = this_cpc(pmu_ctx->pmu); + if (cpc->task_epc != pmu_ctx) + continue; + if (cpc->sched_cb_usage && pmu_ctx->pmu->sched_task) pmu_ctx->pmu->sched_task(pmu_ctx, task, sched_in); } @@ -3924,15 +3927,17 @@ static void perf_pmu_sched_task(struct task_struct *prev, struct task_struct *next, bool sched_in) { - struct perf_cpu_context *cpuctx = this_cpu_ptr(&perf_cpu_context); struct perf_cpu_pmu_context *cpc, *cpc2; - /* cpuctx->task_ctx will be handled in perf_event_context_sched_in/out */ - if (prev == next || cpuctx->task_ctx) + if (prev == next) return; - list_for_each_entry_safe(cpc, cpc2, this_cpu_ptr(&sched_cb_list), sched_cb_entry) + list_for_each_entry_safe(cpc, cpc2, this_cpu_ptr(&sched_cb_list), sched_cb_entry) { + if (cpc->task_epc) + continue; + __perf_pmu_sched_task(cpc, sched_in ? next : prev, sched_in); + } } static void perf_event_switch(struct task_struct *task, -- cgit v1.2.3 From 4409a85735cdca5c4c400c0dad1feee091872eee Mon Sep 17 00:00:00 2001 From: Liang Luo Date: Wed, 23 Sep 2026 19:07:37 +0800 Subject: sched_ext: Count SCX_EV_SUB_BYPASS_DISPATCH in the dispatch fallback When a descendant scheduler enters bypass mode, its tasks are parked in the bypass DSQs of the nearest non-bypassing ancestor, which is then responsible for running them. On behalf of such a non-bypassing host, scx_dispatch_sched() consumes those bypass DSQs from two places: the attempt made every SCX_BYPASS_HOST_NTH dispatches, and the end-of-dispatch fallback that keeps the CPU from going idle while bypassed descendants still have tasks queued. The former increments SCX_EV_SUB_BYPASS_DISPATCH but the latter does not, even though both perform the same scx_consume_dispatch_q() on the same bypass DSQ. The descendant bypass dispatches done by the fallback are therefore missing from the counter exposed via sysfs, scx_dump_state() and the scx_bpf_events() kfunc, which under-reports the actual number of such dispatches. Add the missing __scx_add_event() so the fallback counts them too. When @sch itself is bypassing, scx_dispatch_sched() takes the earlier self-bypass branch and returns before reaching these host paths; that mode is accounted for by SCX_EV_BYPASS_DISPATCH at enqueue time and is intentionally left unchanged. Fixes: 025b1bd41965 ("sched_ext: Implement hierarchical bypass mode") Signed-off-by: Liang Luo Signed-off-by: Tejun Heo --- kernel/sched/ext/inlines.h | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'kernel') diff --git a/kernel/sched/ext/inlines.h b/kernel/sched/ext/inlines.h index ed423bcc26b8..2ff5479334cb 100644 --- a/kernel/sched/ext/inlines.h +++ b/kernel/sched/ext/inlines.h @@ -129,8 +129,10 @@ scx_dispatch_sched(struct scx_sched *sch, struct rq *rq, * scheduler's ops.dispatch() doesn't yield any tasks. */ if (scx_bypass_dsp_enabled(sch) && - scx_consume_dispatch_q(sch, rq, scx_bypass_dsq(sch, cpu), 0)) + scx_consume_dispatch_q(sch, rq, scx_bypass_dsq(sch, cpu), 0)) { + __scx_add_event(sch, SCX_EV_SUB_BYPASS_DISPATCH, 1); return SCX_DSP_LOCAL; + } return SCX_DSP_NONE; } -- cgit v1.2.3 From a0bb6fac53fa7cf1cadb487b43d4c9276a6b82e3 Mon Sep 17 00:00:00 2001 From: Zhan Xusheng Date: Fri, 18 Sep 2026 21:29:15 +0800 Subject: sched/core: Account PSI IRQ time to the execution context, not the scheduling context psi_account_irqtime() has two callers which share rq->psi_irq_time, and they disagree about the context: __schedule() passes the outgoing rq->curr, sched_tick() passes rq->donor. Under proxy execution the donor is blocked on a mutex while rq->curr burns the CPU. The tick charges PSI_IRQ_FULL to the donor's cgroup and advances the timestamp, so the call from __schedule() then finds delta <= 0 and charges nothing. The delta is not counted twice, it lands on the wrong cgroup. Pass rq->curr, which is what the call read before commit af0c8b2bf67b ("sched: Split scheduler and execution contexts") renamed 'curr' to 'donor' across sched_tick(). Without CONFIG_SCHED_PROXY_EXEC the two rq members are a union, so this only changes anything where that option is set, and it depends on EXPERT. Fixes: af0c8b2bf67b ("sched: Split scheduler and execution contexts") Signed-off-by: Zhan Xusheng Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Ingo Molnar Link: https://patch.msgid.link/20260918132915.1236312-1-zhanxusheng@xiaomi.com --- kernel/sched/core.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'kernel') diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 0b846a13c628..1fe40de6ebe3 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -5798,7 +5798,7 @@ void sched_tick(void) curr = rq->curr; donor = rq->donor; - psi_account_irqtime(rq, donor, NULL); + psi_account_irqtime(rq, curr, NULL); update_rq_clock(rq); hw_pressure = arch_scale_hw_pressure(cpu_of(rq)); -- cgit v1.2.3 From c3a66e5f5bab3912e9f84223c5a982bf4333d5a1 Mon Sep 17 00:00:00 2001 From: Donggeun Yoo Date: Thu, 24 Sep 2026 19:23:20 +0900 Subject: bpf: Zero-fill other CPUs when BPF_F_CPU creates a per-cpu hash element pcpu_init_value() initializes the per-cpu area of a newly created [lru_]percpu_hash element. The area is recycled, so when the value comes from a BPF program (onallcpus == false) it writes the running CPU's slot and zeroes the rest. bpf_percpu_hash_update() passes onallcpus == true, which delegates to pcpu_copy_value(). pcpu_copy_value() writes only the CPU named in map_flags when BPF_F_CPU is set, so on the create path the other slots keep the recycled element's values: update(k1, 0xdeadc0de, BPF_F_ALL_CPUS) every CPU holds 0xdeadc0de delete(k1) element back on the freelist update(k2, 0xc0ffee, BPF_F_CPU | 0) creates, writes CPU 0 only lookup(k2) CPU 0 0xc0ffee, rest 0xdeadc0de Zero-fill the other CPUs on that arm too. Fixes: c6936161fd55 ("bpf: Add BPF_F_CPU and BPF_F_ALL_CPUS flags support for percpu_hash and lru_percpu_hash maps") Signed-off-by: Donggeun Yoo Signed-off-by: Alexei Starovoitov Link: https://patch.msgid.link/20260924102321.2120434-2-donggeunyoo.kernel@gmail.com --- kernel/bpf/hashtab.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) (limited to 'kernel') diff --git a/kernel/bpf/hashtab.c b/kernel/bpf/hashtab.c index 4f495dcbf670..f9464e566f10 100644 --- a/kernel/bpf/hashtab.c +++ b/kernel/bpf/hashtab.c @@ -1054,14 +1054,17 @@ static void pcpu_init_value(struct bpf_htab *htab, void __percpu *pptr, /* When not setting the initial value on all cpus, zero-fill element * values for other cpus. Otherwise, bpf program has no way to ensure * known initial values for cpus other than current one - * (onallcpus=false always when coming from bpf prog). + * (onallcpus=false always when coming from bpf prog, + * map_flags & BPF_F_CPU when coming from syscall but setting + * only one cpu). */ - if (!onallcpus) { - int current_cpu = raw_smp_processor_id(); + if (!onallcpus || (map_flags & BPF_F_CPU)) { + int init_cpu = (map_flags & BPF_F_CPU) ? map_flags >> 32 : + raw_smp_processor_id(); int cpu; for_each_possible_cpu(cpu) { - if (cpu == current_cpu) + if (cpu == init_cpu) copy_map_value(&htab->map, per_cpu_ptr(pptr, cpu), value); else /* Since elem is preallocated, we cannot touch special fields */ zero_map_value(&htab->map, per_cpu_ptr(pptr, cpu)); -- cgit v1.2.3 From 1765a153d985c231357145e26798f9408db10e42 Mon Sep 17 00:00:00 2001 From: Guopeng Zhang Date: Thu, 24 Sep 2026 17:15:36 +0800 Subject: cgroup/pids: Restore pids.events notifications in local mode A fork rejected by the pids controller increments the counter reported by pids.events. When local event accounting is selected, however, pids_event() returns after notifying only events_local_file, leaving pids.events pollers asleep. On legacy hierarchies, pids.events.local does not exist. With pids_localevents, pids.events reports the same local counter. In both cases, pids.events changes without generating a notification. This can be reproduced with a pids_localevents mount: mkdir /tmp/test mount -t cgroup2 -o pids_localevents none /tmp/test mkdir /tmp/test/t echo 1 > /tmp/test/t/pids.max cat /tmp/test/t/pids.events # max 0 timeout 3 inotifywait -e modify /tmp/test/t/pids.events & sh -c 'echo $$ > /tmp/test/t/cgroup.procs; (true &)' 2>/dev/null wait cat /tmp/test/t/pids.events # max 1 Without this patch, inotifywait times out without reporting an event. Notify pids.events before returning from the local event path. Fixes: 3f26a885a068 ("cgroup/pids: Add pids.events.local") Cc: stable@vger.kernel.org # v6.11+ Signed-off-by: Guopeng Zhang Signed-off-by: Tejun Heo --- kernel/cgroup/pids.c | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'kernel') diff --git a/kernel/cgroup/pids.c b/kernel/cgroup/pids.c index ecbb839d2acb..78cdc0558d0c 100644 --- a/kernel/cgroup/pids.c +++ b/kernel/cgroup/pids.c @@ -253,6 +253,11 @@ static void pids_event(struct pids_cgroup *pids_forking, } if (!cgroup_subsys_on_dfl(pids_cgrp_subsys) || cgrp_dfl_root.flags & CGRP_ROOT_PIDS_LOCAL_EVENTS) { + /* + * pids.events reports the local counter on legacy hierarchies + * and when pids_localevents is enabled. + */ + cgroup_file_notify(&p->events_file); cgroup_file_notify(&p->events_local_file); return; } -- cgit v1.2.3 From ad139384ecddb6f3e7e3c3c12765aafae0e39670 Mon Sep 17 00:00:00 2001 From: Alexei Starovoitov Date: Thu, 24 Sep 2026 18:23:53 +0000 Subject: bpf: Fix overflow of jump offset in constant blinding bpf_jit_blind_insn() rewrites 'if rX op imm goto off' into: AX = imm ^ rnd AX ^= rnd if rX op AX goto off and subtracts 2 from off when the jump is backward. off is s16, so -32767 and -32768 wrap and the jump goes 32767 insns forward, past the end of the prog. The jump is inside the patch, hence bpf_adj_branches() doesn't check it. The kernel crashes when such prog runs with bpf_jit_harden=2. Return -ERANGE in such case. bpf_jit_blind_constants() fails the same way when blinding of other insns moves a jump out of range. Fixes: 4f3446bb809f ("bpf: add generic constant blinding for use in jits") Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/20260924182353.277516-1-alexei.starovoitov@gmail.com Signed-off-by: Kumar Kartikeya Dwivedi --- kernel/bpf/core.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) (limited to 'kernel') diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c index 2e3bf8113ae9..7f11555a5070 100644 --- a/kernel/bpf/core.c +++ b/kernel/bpf/core.c @@ -1362,7 +1362,7 @@ static int bpf_jit_blind_insn(const struct bpf_insn *from, { struct bpf_insn *to = to_buff; u32 imm_rnd = get_random_u32(); - s16 off; + int off; BUILD_BUG_ON(BPF_REG_PARAMS + 2 != MAX_BPF_JIT_REG); BUILD_BUG_ON(BPF_REG_AX + 1 != MAX_BPF_JIT_REG); @@ -1438,6 +1438,8 @@ static int bpf_jit_blind_insn(const struct bpf_insn *from, off = from->off; if (off < 0) off -= 2; + if (off < S16_MIN) + return -ERANGE; *to++ = BPF_ALU64_IMM(BPF_MOV, BPF_REG_AX, imm_rnd ^ from->imm); *to++ = BPF_ALU64_IMM(BPF_XOR, BPF_REG_AX, imm_rnd); *to++ = BPF_JMP_REG(from->code, from->dst_reg, BPF_REG_AX, off); @@ -1458,6 +1460,8 @@ static int bpf_jit_blind_insn(const struct bpf_insn *from, off = from->off; if (off < 0) off -= 2; + if (off < S16_MIN) + return -ERANGE; *to++ = BPF_ALU32_IMM(BPF_MOV, BPF_REG_AX, imm_rnd ^ from->imm); *to++ = BPF_ALU32_IMM(BPF_XOR, BPF_REG_AX, imm_rnd); *to++ = BPF_JMP32_REG(from->code, from->dst_reg, BPF_REG_AX, @@ -1606,7 +1610,9 @@ struct bpf_prog *bpf_jit_blind_constants(struct bpf_verifier_env *env, struct bp if (!rewritten) continue; - if (env) + if (rewritten < 0) + tmp = ERR_PTR(rewritten); + else if (env) tmp = bpf_patch_insn_data(env, i, insn_buff, rewritten); else tmp = bpf_patch_insn_single(clone, i, insn_buff, rewritten); -- cgit v1.2.3 From 5bfa9f1a9dcb6ecb607adbc1c0226605c972935b Mon Sep 17 00:00:00 2001 From: Andrea Parri Date: Thu, 24 Sep 2026 11:21:39 +0200 Subject: kprobes: Fix permanent hang when flushing the kprobe optimizer Writing 0 to /proc/sys/debug/kprobes-optimization while a kprobe is jump-optimized never returns. The writer sleeps in D state forever with kprobe_sysctl_mutex held, so any later read or write of that sysctl hangs as well. For example, with vfs_read+9 as an optimizable address in this build: # cd /sys/kernel/tracing # echo 'p:myprobe vfs_read+9' >> kprobe_events # echo 1 > events/kprobes/myprobe/enable # # wait until /sys/kernel/debug/kprobes/list shows [OPTIMIZED] # echo 0 > /proc/sys/debug/kprobes-optimization INFO: task sh:246 blocked for more than 10 seconds. Call Trace: __schedule+0x1176/0x4f70 schedule+0xdc/0x2c0 schedule_timeout+0x17b/0x260 wait_for_completion+0x173/0x3c0 wait_for_kprobe_optimizer_locked+0xbc/0x130 proc_kprobes_optimization_handler+0x156/0x1b0 proc_sys_call_handler+0x324/0x490 vfs_write+0x52d/0xfe0 ksys_write+0xff/0x200 do_syscall_64+0x106/0x630 entry_SYSCALL_64_after_hwframe+0x77/0x7f ... INFO: task cat:265 is blocked on a mutex likely owned by task sh:246. wait_for_kprobe_optimizer_locked() reinitializes optimizer_completion, asks the optimizer thread to flush and sleeps in wait_for_completion(). The thread drains the (un)optimizing lists, but calls complete() only if completion_done() is true, i.e. if the completion is already done, which never happens while someone waits. disarm_all_kprobes() and kprobe_trace_self_tests_init() wait the same way. Calling complete() unconditionally would not be enough: the waiter drops kprobe_mutex while it sleeps, and nothing else serializes the sysctl handler against the debugfs "enabled" file. A second flusher that still finds the lists non-empty, e.g. because a disabled probe is queued for unoptimizing, reinitializes the completion under the first: sysctl write debugfs "enabled" write unoptimize_all_kprobes() wait_for_kprobe_optimizer_locked() init_completion(c) mutex_unlock(&kprobe_mutex) wait_for_completion(c) disarm_all_kprobes() wait_for_kprobe_optimizer_locked() init_completion(c) // c->wait is reset, the first // waiter is off the queue mutex_unlock(&kprobe_mutex) wait_for_completion(c) kprobe_optimizer() complete(c) // wakes the debugfs writer only where c is &optimizer_completion. Lining up the two writes during an optimizer pass loses the sysctl writer this way. Replace the completion with a counter of optimizer passes, bumped at the end of each pass and signalled with wake_up_var_locked(), both under kprobe_mutex. A flusher samples the count and waits with wait_var_event_mutex(), which drops kprobe_mutex only while sleeping, so a new count means a whole pass ran in the meantime. Nothing is reinitialized, so several flushers can sleep in the wait at once. Link: https://lore.kernel.org/all/20260924092142.199198-1-parri.andrea@gmail.com/ Fixes: 73c12f209462 ("kprobes: Use dedicated kthread for kprobe optimizer") Cc: stable@vger.kernel.org Assisted-by: LLM Signed-off-by: Andrea Parri Signed-off-by: Masami Hiramatsu (Google) --- kernel/kprobes.c | 22 ++++++++++++++-------- 1 file changed, 14 insertions(+), 8 deletions(-) (limited to 'kernel') diff --git a/kernel/kprobes.c b/kernel/kprobes.c index 6337da5cab9e..4edd8ca5c657 100644 --- a/kernel/kprobes.c +++ b/kernel/kprobes.c @@ -42,6 +42,7 @@ #include #include #include +#include #include #include @@ -526,7 +527,8 @@ enum { OPTIMIZER_ST_FLUSHING = 2, }; -static DECLARE_COMPLETION(optimizer_completion); +/* Bumped at the end of each kprobe_optimizer() pass, under 'kprobe_mutex' */ +static unsigned long optimizer_passes; #define OPTIMIZE_DELAY 5 @@ -654,9 +656,9 @@ static void kprobe_optimizer(void) do_free_cleaned_kprobes(); } - /* Step 5: Kick optimizer again if needed. But if there is a flush requested, */ - if (completion_done(&optimizer_completion)) - complete(&optimizer_completion); + /* Step 5: Wake up flushers, and kick optimizer again if needed. */ + optimizer_passes++; + wake_up_var_locked(&optimizer_passes, &kprobe_mutex); if (!list_empty(&optimizing_list) || !list_empty(&unoptimizing_list)) kick_kprobe_optimizer(); /*normal kick*/ @@ -708,7 +710,8 @@ static void wait_for_kprobe_optimizer_locked(void) lockdep_assert_held(&kprobe_mutex); while (!list_empty(&optimizing_list) || !list_empty(&unoptimizing_list)) { - init_completion(&optimizer_completion); + unsigned long passes = optimizer_passes; + /* * Set state to OPTIMIZER_ST_FLUSHING and wake up the thread if it's * idle. If it's already kicked, it will see the state change. @@ -717,9 +720,12 @@ static void wait_for_kprobe_optimizer_locked(void) OPTIMIZER_ST_FLUSHING) != OPTIMIZER_ST_FLUSHING) wake_up(&kprobe_optimizer_wait); - mutex_unlock(&kprobe_mutex); - wait_for_completion(&optimizer_completion); - mutex_lock(&kprobe_mutex); + /* + * kprobe_optimizer() holds 'kprobe_mutex' for a whole pass, which + * this drops while sleeping, so a new count means a full pass ran. + */ + wait_var_event_mutex(&optimizer_passes, + optimizer_passes != passes, &kprobe_mutex); } } -- cgit v1.2.3 From ab39974240a0cff765f3bb9cce81d8001ffdb144 Mon Sep 17 00:00:00 2001 From: Kumar Kartikeya Dwivedi Date: Fri, 25 Sep 2026 08:46:51 +0200 Subject: bpf: Hold map BTF for the memory allocator destructor record bpf_ma_set_dtor() duplicates map->record so that the bpf_mem_alloc destructor can release the special fields of hash and rhash map elements once the allocator frees them for good. btf_record_dup() only acquires references on kernel and module BTF. Fields whose types live in the map BTF keep pointing into it: a kptr to a local type refers to map->btf, and a list_head or rb_root field carries a value_rec owned by the struct meta table of map->btf. That borrowed state can outlive the map. When RCU callbacks are still in flight, bpf_mem_alloc_destroy() copies the allocator and defers the final drain, together with the destructor context, to a workqueue. bpf_map_free() then frees map->record and drops the map's BTF reference as soon as map_free() returns. Once the program that loaded the BTF is gone as well, the BTF is freed while the worker still uses the duplicate. The worker dereferences it through btf_is_kernel() and btf_find_struct_meta() in bpf_obj_free_fields() when destroying elements that were freed under RCU, and through btf_is_kernel() in btf_record_free() when releasing the context itself: BUG: KASAN: slab-use-after-free in btf_is_kernel+0x19/0x30 Read of size 1 at addr ffff88811505dce8 by task kworker/u16:2/50 Workqueue: events_unbound free_mem_alloc_deferred Call Trace: btf_is_kernel+0x19/0x30 btf_record_free+0xc7/0xf0 htab_dtor_ctx_free+0x1a/0x30 free_mem_alloc_no_barrier+0x39/0x230 free_mem_alloc_deferred+0x2a/0x40 process_scheduled_works+0x5ce/0x9d0 worker_thread+0x42a/0x5e0 kthread+0x1f5/0x230 ret_from_fork+0x1dd/0x390 ret_from_fork_asm+0x1a/0x30 Allocated by task 358: __kmalloc_cache_noprof+0x287/0x510 btf_new_fd+0xf7/0x3d0 __sys_bpf+0x487/0x840 Freed by task 0: kfree+0x186/0x560 rcu_core+0x6f6/0xd40 Freeing a map that still holds more elements than the allocator's high watermark is enough to get there, because the bulk free during teardown queues the RCU callback that makes bpf_mem_alloc_destroy() defer. Non-preallocated hash maps and resizable hash maps both register the destructor and are affected alike. Keep one reference on the map BTF in the destructor context. Every non-kernel pointer in the duplicated record is either map->btf or memory owned by it, so a single reference covers kptrs, list heads, and rb roots, and mirrors what bpf_map_meta_alloc() does for the duplicated record of an inner map. Release it only after the duplicated record has been freed: the worker is preemptible and not in an RCU read-side critical section, so dropping the last reference first would let the BTF be freed while btf_record_free() still reads its fields. Fixes: 1df97a7453ee ("bpf: Register dtor for freeing special fields") Reported-by: Yuan Chen Signed-off-by: Kumar Kartikeya Dwivedi Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/20260901062845.1379760-3-chenyuan_fl@163.com Link: https://patch.msgid.link/20260925064652.2261885-1-memxor@gmail.com --- kernel/bpf/hashtab.c | 17 ++++++++++++++++- 1 file changed, 16 insertions(+), 1 deletion(-) (limited to 'kernel') diff --git a/kernel/bpf/hashtab.c b/kernel/bpf/hashtab.c index f9464e566f10..548eb1cc7c45 100644 --- a/kernel/bpf/hashtab.c +++ b/kernel/bpf/hashtab.c @@ -128,6 +128,7 @@ struct htab_elem { struct htab_btf_record { struct btf_record *record; + struct btf *btf; u32 key_size; }; @@ -497,8 +498,13 @@ static void htab_dtor_ctx_free(void *ctx) { struct htab_btf_record *hrec = ctx; + /* + * The duplicated record still points into the map BTF, so free it + * before dropping the reference that keeps that BTF alive. + */ btf_record_free(hrec->record); - kfree(ctx); + btf_put(hrec->btf); + kfree(hrec); } static int bpf_ma_set_dtor(struct bpf_map *map, struct bpf_mem_alloc *ma, @@ -521,6 +527,15 @@ static int bpf_ma_set_dtor(struct bpf_map *map, struct bpf_mem_alloc *ma, kfree(hrec); return err; } + /* + * btf_record_dup() only acquires kernel and module BTF. Fields whose + * types live in the map BTF keep pointing into it: kptrs to local + * types refer to map->btf, and graph roots carry a value record owned + * by its struct meta table. The context can outlive the map when the + * allocator defers its teardown, so hold a reference of our own. + */ + hrec->btf = map->btf; + btf_get(hrec->btf); bpf_mem_alloc_set_dtor(ma, dtor, htab_dtor_ctx_free, hrec); return 0; } -- cgit v1.2.3 From aa650d87a498844060eecb1d336f4d46f4d1b0b3 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?J=C3=A9r=C3=A9my=20Jean?= Date: Tue, 22 Sep 2026 20:27:35 +0000 Subject: audit: fix exe mark UAF in kill_rules() MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit kill_rules() removes mixed AUDIT_DIR and AUDIT_EXE rules when an audit tree is pruned. It drops entry->rule.exe before removing the rule from the RCU-visible filter lists. After a rule has been installed with AUDIT_ADD_RULE, which requires CAP_AUDIT_CONTROL, removing the watched directory can race with another task that is still evaluating the rule. In that case, fsnotify can free the executable mark before the reader reaches audit_mark_compare(), causing a use-after-free. KASAN reports: BUG: KASAN: slab-use-after-free in audit_mark_compare+0x8d/0xa0 Unlink the published rules from the RCU-visible lists and retain them on tree->rules for cleanup. If any rule has an executable mark, wait for a single RCU grace period before removing the marks and scheduling the entries for freeing. Otherwise, call_rcu() already provides the required deferred freeing without a synchronous wait. Cc: stable@vger.kernel.org Fixes: 34d99af52ad4 ("audit: implement audit by executable") Assisted-by: Codex:gpt-5 Signed-off-by: Jérémy Jean Reviewed-by: Ricardo Robaina Tested-by: Ricardo Robaina Reviewed-by: Bradley Morgan Signed-off-by: Paul Moore --- kernel/audit_tree.c | 24 ++++++++++++++++++++---- 1 file changed, 20 insertions(+), 4 deletions(-) (limited to 'kernel') diff --git a/kernel/audit_tree.c b/kernel/audit_tree.c index 1ed19b775912..f2e81be8265e 100644 --- a/kernel/audit_tree.c +++ b/kernel/audit_tree.c @@ -545,22 +545,38 @@ static void kill_rules(struct audit_context *context, struct audit_tree *tree) { struct audit_krule *rule, *next; struct audit_entry *entry; + bool need_sync = false; list_for_each_entry_safe(rule, next, &tree->rules, rlist) { entry = container_of(rule, struct audit_entry, rule); - list_del_init(&rule->rlist); if (rule->tree) { /* not a half-baked one */ audit_tree_log_remove_rule(context, rule); - if (entry->rule.exe) - audit_remove_mark(entry->rule.exe); rule->tree = NULL; list_del_rcu(&entry->list); list_del(&entry->rule.list); - call_rcu(&entry->rcu, audit_free_rule_rcu); + if (entry->rule.exe) + need_sync = true; + } else { + list_del_init(&rule->rlist); } } + + if (list_empty(&tree->rules)) + return; + + if (need_sync) + synchronize_rcu(); + + list_for_each_entry_safe(rule, next, &tree->rules, rlist) { + entry = container_of(rule, struct audit_entry, rule); + + list_del_init(&rule->rlist); + if (entry->rule.exe) + audit_remove_mark(entry->rule.exe); + call_rcu(&entry->rcu, audit_free_rule_rcu); + } } /* -- cgit v1.2.3 From 31c88350b7dd1522792f726f79607f31bb55c50f Mon Sep 17 00:00:00 2001 From: Hui Peng Date: Thu, 24 Sep 2026 04:27:27 +0000 Subject: cgroup/cpuset: Return PERR_NOCPUS in remote_partition_enable() on subpartitions_cpus conflict When a remote partition is created underneath an existing local partition via a non-partition (PRS_MEMBER) intermediate cgroup, update_prstate() sees parent->partition_root_state == PRS_MEMBER and calls remote_partition_enable(). Commit 86888c7bd117 ("cgroup/cpuset: Add warnings to catch inconsistency in exclusive CPUs") replaced the cpumask_intersects(tmp->new_cpus, subpartitions_cpus) error check in remote_partition_enable() with WARN_ON_ONCE(). As a result, remote_partition_enable() emits a warning and proceeds to enable the remote partition on CPUs that are already owned by the ancestor local partition in subpartitions_cpus. This can be reproduced on Linux 7.3.0-rc3 with: mkdir -p /tmp/cg1 mount -t cgroup2 none /tmp/cg1 echo "+cpuset" > /tmp/cg1/cgroup.subtree_control mkdir /tmp/cg1/A echo 1 > /tmp/cg1/A/cpuset.cpus echo 1 > /tmp/cg1/A/cpuset.cpus.exclusive echo root > /tmp/cg1/A/cpuset.cpus.partition echo "+cpuset" > /tmp/cg1/A/cgroup.subtree_control mkdir /tmp/cg1/A/B echo 1 > /tmp/cg1/A/B/cpuset.cpus echo 1 > /tmp/cg1/A/B/cpuset.cpus.exclusive echo "+cpuset" > /tmp/cg1/A/B/cgroup.subtree_control mkdir /tmp/cg1/A/B/D echo 1 > /tmp/cg1/A/B/D/cpuset.cpus echo 1 > /tmp/cg1/A/B/D/cpuset.cpus.exclusive echo root > /tmp/cg1/A/B/D/cpuset.cpus.partition which triggers: WARNING: kernel/cgroup/cpuset.c:1594 at remote_partition_enable+0x1c1/0x300 and leaves both /tmp/cg1/A and /tmp/cg1/A/B/D as active root partitions claiming exclusive CPU 1. Fix this by returning PERR_NOCPUS when tmp->new_cpus intersects subpartitions_cpus in remote_partition_enable(), matching the error code used by remote_cpus_update() for the same subpartitions_cpus conflict, and add a regression test case to tools/testing/selftests/cgroup/test_cpuset_prs.sh. Tested in QEMU on Linux 7.3.0-rc3 using the reproducer above and tools/testing/selftests/cgroup/test_cpuset_prs.sh. Fixes: 86888c7bd117 ("cgroup/cpuset: Add warnings to catch inconsistency in exclusive CPUs") Suggested-by: Guopeng Zhang Cc: stable@vger.kernel.org Assisted-by: LLM Signed-off-by: Hui Peng Reviewed-by: Waiman Long Signed-off-by: Tejun Heo --- kernel/cgroup/cpuset.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'kernel') diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c index 8f24171b6055..1fcec89a28b9 100644 --- a/kernel/cgroup/cpuset.c +++ b/kernel/cgroup/cpuset.c @@ -1591,10 +1591,11 @@ static int remote_partition_enable(struct cpuset *cs, int new_prs, * above it or remote partition root underneath it is not allowed. */ compute_excpus(cs, tmp->new_cpus); - WARN_ON_ONCE(cpumask_intersects(tmp->new_cpus, subpartitions_cpus)); if (!cpumask_intersects(tmp->new_cpus, cpu_active_mask) || cpumask_subset(top_cpuset.effective_cpus, tmp->new_cpus)) return PERR_INVCPUS; + if (cpumask_intersects(tmp->new_cpus, subpartitions_cpus)) + return PERR_NOCPUS; if (((new_prs == PRS_ISOLATED) && !isolated_cpus_can_update(tmp->new_cpus, NULL)) || prstate_housekeeping_conflict(new_prs, tmp->new_cpus)) -- cgit v1.2.3 From 94480606a677deb68d5622cf0ded88626514b3f2 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Sat, 26 Sep 2026 09:23:02 -1000 Subject: sched_ext: Add a size argument to scx_bpf_cid_topo() so struct scx_cid_topo can grow scx_bpf_cid_topo() copies struct scx_cid_topo into a buffer the BPF program sized from its own vmlinux.h while the verifier sizes the write from the running kernel's BTF. The struct may grow and each growth then breaks every scheduler built against the older layout, rejected at load or written past its buffer. This is the usual hole for a struct handed to BPF, closed elsewhere with a size argument, and it was missed here. Take the buffer size, copy the smaller of it and the kernel's struct and set the rest to -1. Accesses to the copy are CO-RE relocated, so the struct can grow by appending fields, which its comment now states. The kfunc changes in place: the cid interface is still being finalized and no released scheduler uses the current form. Fixes: e9b55af47edf ("sched_ext: Add topological CPU IDs (cids)") Cc: stable@vger.kernel.org # v7.2+ Signed-off-by: Tejun Heo Reviewed-by: Andrea Righi --- kernel/sched/ext/cid.c | 26 ++++++++++++++++---------- kernel/sched/ext/types.h | 4 ++++ 2 files changed, 20 insertions(+), 10 deletions(-) (limited to 'kernel') diff --git a/kernel/sched/ext/cid.c b/kernel/sched/ext/cid.c index 39f88deb94bc..d4d5f537832a 100644 --- a/kernel/sched/ext/cid.c +++ b/kernel/sched/ext/cid.c @@ -912,30 +912,36 @@ bool scx_cmask_empty(const struct scx_cmask *m) /** * scx_bpf_cid_topo - Copy out per-cid topology info * @cid: cid to look up - * @out__uninit: where to copy the topology info; fully written by this call + * @out: where to copy the topology info + * @out__sz: size of @out, the program's sizeof(struct scx_cid_topo) * @aux: implicit BPF argument to access bpf_prog_aux hidden from BPF progs * - * Fill @out__uninit with the topology info for @cid. Trigger scx_error() if - * @cid is out of range. If @cid is valid but in the no-topo section, all fields - * are set to -1. All fields are also set to -1 when no cid tables have been - * published yet, which a program may observe while racing the root enable. + * Fill @out with the topology info for @cid. Trigger scx_error() if @cid is out + * of range. If @cid is valid but in the no-topo section, all fields are set to + * -1. All fields are also set to -1 when no cid tables have been published yet, + * which a program may observe while racing the root enable. + * + * The program's struct may be older or newer than the kernel's. The smaller of + * @out__sz and the kernel's size is copied and the rest of @out is set to -1. */ -__bpf_kfunc void scx_bpf_cid_topo(s32 cid, struct scx_cid_topo *out__uninit, +__bpf_kfunc void scx_bpf_cid_topo(s32 cid, struct scx_cid_topo *out, size_t out__sz, const struct bpf_prog_aux *aux) { + size_t len = min(out__sz, sizeof(*out)); struct scx_cid_topo *topo; struct scx_sched *sch; + /* the error cases and fields the kernel lacks read as -1 */ + memset(out, 0xff, out__sz); + guard(rcu)(); sch = scx_prog_sched(aux); topo = rcu_dereference(scx_cid_topo); - if (unlikely(!sch) || !cid_valid(sch, cid) || unlikely(!topo)) { - *out__uninit = SCX_CID_TOPO_NEG; + if (unlikely(!sch) || !cid_valid(sch, cid) || unlikely(!topo)) return; - } - *out__uninit = topo[cid]; + memcpy(out, &topo[cid], len); } __bpf_kfunc_end_defs(); diff --git a/kernel/sched/ext/types.h b/kernel/sched/ext/types.h index 943d8d429a2c..139176cf9fc6 100644 --- a/kernel/sched/ext/types.h +++ b/kernel/sched/ext/types.h @@ -70,6 +70,10 @@ enum scx_consts { * smaller shards if the LLC exceeds the target size. No-topo cids are packed * into their own max-sized shards. * + * New fields are appended, never inserted: scx_bpf_cid_topo() copies this + * struct out sized by the program's own layout, and an older program's copy + * must stay a prefix of the kernel's. + * * @core_cid: first cid of this cid's core (smt-sibling group) * @core_idx: global index of that core, in [0, nr_cores_at_init) * @llc_cid: first cid of this cid's LLC -- cgit v1.2.3 From c79cf15eb35a4c703bf18f8c33c47e80dd660f8e Mon Sep 17 00:00:00 2001 From: Hao Ge Date: Thu, 27 Aug 2026 11:05:03 +0800 Subject: module: fix lost error code from codetag_load_module() If codetag_load_module() fails, err is not set to reflect the failure and load_module() returns 0 after the module has been torn down. Also, if the module is a livepatch, mod->klp_info allocated by copy_module_elf() leaks on this error path. Free it via a new livepatch_cleanup label. Link: https://lore.kernel.org/20260827030503.49171-1-hao.ge@linux.dev Fixes: 044d2aee6c57 ("alloc_tag: handle module codetag load errors as module load failures") Signed-off-by: Hao Ge Signed-off-by: Andrew Morton Reported-by: Sashiko Suggested-by: Petr Pavlu Reviewed-by: Bradley Morgan Cc: Aaron Tomlin Cc: Luis Chamberalin Cc: Sami Tolvanen Cc: Suren Baghdasaryan Cc: --- kernel/module/main.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) (limited to 'kernel') diff --git a/kernel/module/main.c b/kernel/module/main.c index d0e1e0bd2ad0..c1b34dc1e89a 100644 --- a/kernel/module/main.c +++ b/kernel/module/main.c @@ -3581,8 +3581,9 @@ static int load_module(struct load_info *info, const char __user *uargs, goto sysfs_cleanup; } - if (codetag_load_module(mod)) - goto sysfs_cleanup; + err = codetag_load_module(mod); + if (err) + goto livepatch_cleanup; /* Get rid of temporary copy. */ free_copy(info, flags); @@ -3592,6 +3593,9 @@ static int load_module(struct load_info *info, const char __user *uargs, return do_init_module(mod); + livepatch_cleanup: + if (is_livepatch_module(mod)) + free_module_elf(mod); sysfs_cleanup: mod_sysfs_teardown(mod); coming_cleanup: -- cgit v1.2.3 From db6365ced4d5855e321f772b240c0e473bcfcdd5 Mon Sep 17 00:00:00 2001 From: Pavankumar Kondeti Date: Fri, 25 Sep 2026 15:25:12 +0530 Subject: workqueue: Fix NULL current_pwq deref in flush dependency check check_flush_dependency() uses current_wq_worker() to determine whether the caller is a workqueue worker and then dereferences worker->current_pwq to test whether the current workqueue is WQ_MEM_RECLAIM. current_wq_worker() only means that %current has PF_WQ_WORKER set. A kworker can reach check_flush_dependency() while it is not executing a work item. One such path is worker_thread() acting as the pool manager, where create_worker() does GFP_KERNEL allocation and the allocation path invokes the OOM notifier. In that state worker->current_pwq is NULL because current_pwq is set only by process_one_work() and cleared again after the work function returns. [ 416.760634][ T375] Call trace: [ 416.760638][ T375] check_flush_dependency+0x80/0x120 (P) [ 416.760648][ T375] __flush_work+0x98/0x224 [ 416.760657][ T375] flush_work+0x30/0x44 [ 416.760665][ T375] ... [ 416.760710][ T375] blocking_notifier_call_chain+0x58/0xa0 [ 416.760719][ T375] out_of_memory+0xb4/0x458 [ 416.760730][ T375] __alloc_pages_may_oom+0x11c/0x1a8 [ 416.760739][ T375] __alloc_pages_slowpath+0x314/0x46c [ 416.760746][ T375] __alloc_frozen_pages_noprof+0x110/0x1a4 [ 416.760753][ T375] new_slab+0x12c/0x484 [ 416.760759][ T375] ___slab_alloc+0x7a8/0xc7c [ 416.760765][ T375] __slab_alloc+0x74/0xd8 [ 416.760772][ T375] __kmalloc_cache_node_noprof+0x2ac/0x304 [ 416.760779][ T375] alloc_worker+0x28/0x60 [ 416.760785][ T375] create_worker+0x4c/0x20c [ 416.760790][ T375] worker_thread+0xe8/0x2b8 [ 416.760796][ T375] kthread+0x1a8/0x200 [ 416.760805][ T375] ret_from_fork+0x10/0x20 Guard the WQ_MEM_RECLAIM-worker warning with worker->current_pwq. If the kworker is not currently executing a work item, there is no current workqueue to diagnose with that warning. The PF_MEMALLOC warning is left unchanged so explicit reclaim context flushing a !WQ_MEM_RECLAIM target is still reported. Fixes: fca839c00a12 ("workqueue: warn if memory reclaim tries to flush !WQ_MEM_RECLAIM workqueue") Cc: stable@vger.kernel.org Assisted-by: LLM Signed-off-by: Pavankumar Kondeti Signed-off-by: Tejun Heo --- kernel/workqueue.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'kernel') diff --git a/kernel/workqueue.c b/kernel/workqueue.c index b8bec1689b7a..4a73d305d88a 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -3918,7 +3918,7 @@ static void check_flush_dependency(struct workqueue_struct *target_wq, WARN_ONCE(current->flags & PF_MEMALLOC, "workqueue: PF_MEMALLOC task %d(%s) is flushing !WQ_MEM_RECLAIM %s:%ps", current->pid, current->comm, target_wq->name, target_func); - WARN_ONCE(worker && ((worker->current_pwq->wq->flags & + WARN_ONCE(worker && worker->current_pwq && ((worker->current_pwq->wq->flags & (WQ_MEM_RECLAIM | __WQ_LEGACY)) == WQ_MEM_RECLAIM), "workqueue: WQ_MEM_RECLAIM %s:%ps is flushing !WQ_MEM_RECLAIM %s:%ps", worker->current_pwq->wq->name, worker->current_func, -- cgit v1.2.3 From 0fb5751a6e411b1b466c06e50021818d9391df98 Mon Sep 17 00:00:00 2001 From: "Florent Revest (Anthropic)" Date: Sat, 26 Sep 2026 13:55:58 +0000 Subject: bpf: Wait for an RCU tasks grace period before freeing trampoline progs When a prog is detached from a trampoline, it is freed after an RCU grace period, or an RCU tasks trace one if it is sleepable. This covers the tasks that are running the prog, since the prog's enter helper takes the matching read lock before the prog is called. On a preemptible kernel, it doesn't cover a task that was preempted in the trampoline just before the enter helper. That task holds no lock yet, and it calls the prog after it was freed: BUG: KASAN: vmalloc-out-of-bounds in __bpf_prog_enter_recur+0x3a5/0x3f0 Read of size 8 at addr ffffc90000055040 by task candidate/110 CPU: 1 UID: 0 PID: 110 Comm: candidate Not tainted 7.3.0-rc2-00014-g15071f2a1263-dirty #2 PREEMPT(full) Call Trace: __bpf_prog_enter_recur+0x3a5/0x3f0 bpf_trampoline_6442509193+0x37/0xf1 __x64_sys_futex+0x9/0x410 do_syscall_64+0xb0/0x530 ... Wait for an RCU tasks grace period before the existing one when freeing a prog that was linked to a trampoline. An RCU tasks grace period only ends once the tasks that were preempted have run again, and bpf_tramp_image_put() already relies on it to free the image. It doesn't wait for tasks that sleep in the trampoline, the next commit takes care of those. Only progs that were linked to a trampoline can be called this way, so bpf_trampoline_add_prog() marks them and other progs are still freed as before. Fixes: e21aa341785c ("bpf: Fix fexit trampoline.") Reported-by: Junseo Lim Signed-off-by: Florent Revest (Anthropic) Signed-off-by: Alexei Starovoitov Link: https://patch.msgid.link/20260926135605.1217928-2-florent.revest@linux.dev Closes: https://lore.kernel.org/bpf/aqdrwVpanH3WGurX@omen-arch/ --- kernel/bpf/syscall.c | 19 ++++++++++++++++++- kernel/bpf/trampoline.c | 1 + 2 files changed, 19 insertions(+), 1 deletion(-) (limited to 'kernel') diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index 244a939b9d2d..96217b99399d 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -2448,6 +2448,21 @@ static void __bpf_prog_put_rcu(struct rcu_head *rcu) bpf_prog_free(aux->prog); } +/* + * Progs called from a trampoline can also be reached by a task that was + * preempted in the trampoline before the prog's enter helper took its RCU + * read lock, wait for those first. + */ +static void __bpf_prog_put_rcu_tasks(struct rcu_head *rcu) +{ + struct bpf_prog *prog = container_of(rcu, struct bpf_prog_aux, rcu)->prog; + + if (prog->sleepable) + call_rcu_tasks_trace(rcu, __bpf_prog_put_rcu); + else + call_rcu(rcu, __bpf_prog_put_rcu); +} + static void __bpf_prog_put_noref(struct bpf_prog *prog, bool deferred) { bpf_prog_kallsyms_del_all(prog); @@ -2461,7 +2476,9 @@ static void __bpf_prog_put_noref(struct bpf_prog *prog, bool deferred) btf_put(prog->aux->attach_btf); if (deferred) { - if (prog->sleepable) + if (IS_ENABLED(CONFIG_TASKS_RCU) && prog->aux->tramp_linked) + call_rcu_tasks(&prog->aux->rcu, __bpf_prog_put_rcu_tasks); + else if (prog->sleepable) call_rcu_tasks_trace(&prog->aux->rcu, __bpf_prog_put_rcu); else call_rcu(&prog->aux->rcu, __bpf_prog_put_rcu); diff --git a/kernel/bpf/trampoline.c b/kernel/bpf/trampoline.c index 90b70ea0d370..9d69c066a817 100644 --- a/kernel/bpf/trampoline.c +++ b/kernel/bpf/trampoline.c @@ -907,6 +907,7 @@ static int bpf_trampoline_add_prog(struct bpf_trampoline *tr, } hlist_add_head(&node->tramp_hlist, prog_list); + node->link->prog->aux->tramp_linked = true; if (kind == BPF_TRAMP_FSESSION) { tr->progs_cnt[BPF_TRAMP_FENTRY]++; fexit = fsession_exit(node); -- cgit v1.2.3 From 17637e1a581a22466ac3620a91e099683ff9cc6f Mon Sep 17 00:00:00 2001 From: "Florent Revest (Anthropic)" Date: Sat, 26 Sep 2026 13:55:59 +0000 Subject: bpf: Skip detached progs in trampoline images that are still in use bpf_tramp_image_put() makes sure a trampoline image is not freed while a task may still be running in it, but nothing similar is done for the progs called by that image. Detach drops the last prog reference right away and the prog is freed after grace periods, on the basis that a task still in the traced function skips the fexit progs once the nop at ip_after_call is patched to a jump. That leaves out a task sleeping in a sleepable prog that runs before the detached one, which no grace period waits for: CPU 0 CPU 1 in image I, sleeping in prog S detach P from I's trampoline -> new image, bpf_tramp_image_put(I) bpf_prog_put(P), last ref grace periods, P freed back from S __bpf_prog_enter(P) call P->bpf_func If S and P are fexit progs the task is already past the patched jump, and fentry only images don't have one. On x86 this is an int3 in poisoned bpf_prog_pack memory: Oops: int3: 0000 [#1] SMP NOPTI CPU: 18 UID: 0 PID: 94573 Comm: x169 Not tainted 6.18.44 #1 PREEMPT(lazy) RIP: 0010:0xffffffffc0601d8d Call Trace: ? bpf_trampoline_6442515411+0x1a4/0x21b bpf_lsm_bprm_committed_creds+0x5/0x10 security_bprm_committed_creds+0x5f/0x70 begin_new_exec+0x2d6/0x410 ... We hit this in production when progs attached through trampolines got detached while their hooks were busy, and it was independently found with a fuzzer and KASAN. Have the JITs emit a patchable nop in front of each prog call sequence and record it in the image. When a prog is detached, patch its nop to a jump over the call sequence. Progs that stay attached keep running for the tasks that are in the image, and ip_after_call isn't needed anymore. The task can be in any image that isn't freed yet, not only in the current one. It sleeps in image I1 that calls S, P and Q, then P is detached and the trampoline moves to image I2, then Q is detached and its call is still in I1. So the trampoline keeps a list of its images until they are freed, and detaching a prog patches its nop in all of them. Images hold a reference on the trampoline for that long. On riscv and loongarch a jump of any range takes several instructions, and a task preempted in the middle of them could resume into half of the new sequence. The nop is a single instruction there, patched to a near branch through arch_bpf_trampoline_skip(). With the extra nops, BPF_MAX_TRAMP_LINKS progs no longer fit in a page on x86 and arm64 (and already didn't on powerpc), so lower the limit there like s390 does. Fixes: e21aa341785c ("bpf: Fix fexit trampoline.") Reported-by: Sechang Lim Suggested-by: Alexei Starovoitov Signed-off-by: Florent Revest (Anthropic) Signed-off-by: Alexei Starovoitov Link: https://patch.msgid.link/20260926135605.1217928-3-florent.revest@linux.dev Closes: https://lore.kernel.org/bpf/20260815071927.147049-1-zirajs7@gmail.com/ --- kernel/bpf/trampoline.c | 84 +++++++++++++++++++++++++++++++++++++++---------- 1 file changed, 67 insertions(+), 17 deletions(-) (limited to 'kernel') diff --git a/kernel/bpf/trampoline.c b/kernel/bpf/trampoline.c index 9d69c066a817..bf4cb3dd444d 100644 --- a/kernel/bpf/trampoline.c +++ b/kernel/bpf/trampoline.c @@ -401,6 +401,7 @@ static struct bpf_trampoline *bpf_trampoline_lookup(u64 key, unsigned long ip) head = &trampoline_ip_table[hash_64(tr->ip, TRAMPOLINE_HASH_BITS)]; hlist_add_head(&tr->hlist_ip, head); refcount_set(&tr->refcnt, 1); + INIT_LIST_HEAD(&tr->images); for (i = 0; i < BPF_TRAMP_MAX; i++) INIT_HLIST_HEAD(&tr->progs_hlist[i]); out: @@ -565,15 +566,22 @@ static void bpf_tramp_image_free(struct bpf_tramp_image *im) arch_free_bpf_trampoline(im->image, im->size); bpf_jit_uncharge_modmem(im->size); percpu_ref_exit(&im->pcref); + kfree(im->skips); kfree_rcu(im, rcu); } static void __bpf_tramp_image_put_deferred(struct work_struct *work) { struct bpf_tramp_image *im; + struct bpf_trampoline *tr; im = container_of(work, struct bpf_tramp_image, work); + tr = im->tr; + trampoline_lock(tr); + list_del(&im->list); + trampoline_unlock(tr); bpf_tramp_image_free(im); + bpf_trampoline_put(tr); } /* callback, fexit step 3 or fentry step 2 */ @@ -601,7 +609,7 @@ static void __bpf_tramp_image_put_rcu_tasks(struct rcu_head *rcu) struct bpf_tramp_image *im; im = container_of(rcu, struct bpf_tramp_image, rcu); - if (im->ip_after_call) + if (im->call_orig) /* the case of fmod_ret/fexit trampoline and CONFIG_PREEMPTION=y */ percpu_ref_kill(&im->pcref); else @@ -621,9 +629,9 @@ static void bpf_tramp_image_put(struct bpf_tramp_image *im) * * The trampoline is unreachable before bpf_tramp_image_put(). * - * First, patch the trampoline to avoid calling into fexit progs. - * The progs will be freed even if the original function is still - * executing or sleeping. + * Progs are patched out of the image when they are detached, see + * bpf_trampoline_skip_prog(), so they can be freed even if a task is + * still in the image. * In case of CONFIG_PREEMPT=y use call_rcu_tasks() to wait on * first few asm instructions to execute and call into * __bpf_tramp_enter->percpu_ref_get. @@ -637,11 +645,7 @@ static void bpf_tramp_image_put(struct bpf_tramp_image *im) * percpu_ref_kill will be waiting for. Hence the first * call_rcu_tasks() is not necessary. */ - if (im->ip_after_call) { - int err = bpf_arch_text_poke(im->ip_after_call, BPF_MOD_NOP, - BPF_MOD_JUMP, NULL, - im->ip_epilogue); - WARN_ON(err); + if (im->call_orig) { if (IS_ENABLED(CONFIG_TASKS_RCU)) call_rcu_tasks(&im->rcu, __bpf_tramp_image_put_rcu_tasks); else @@ -658,7 +662,7 @@ static void bpf_tramp_image_put(struct bpf_tramp_image *im) call_rcu_tasks_trace(&im->rcu, __bpf_tramp_image_put_rcu_tasks); } -static struct bpf_tramp_image *bpf_tramp_image_alloc(u64 key, int size) +static struct bpf_tramp_image *bpf_tramp_image_alloc(u64 key, int size, int nr_progs) { struct bpf_tramp_image *im; struct bpf_ksym *ksym; @@ -669,6 +673,10 @@ static struct bpf_tramp_image *bpf_tramp_image_alloc(u64 key, int size) if (!im) goto out; + im->skips = kzalloc_objs(*im->skips, nr_progs); + if (!im->skips) + goto out_free_im; + err = bpf_jit_charge_modmem(size); if (err) goto out_free_im; @@ -695,6 +703,7 @@ out_free_image: out_uncharge: bpf_jit_uncharge_modmem(size); out_free_im: + kfree(im->skips); kfree(im); out: return ERR_PTR(err); @@ -771,11 +780,12 @@ again: goto out; } - im = bpf_tramp_image_alloc(tr->key, size); + im = bpf_tramp_image_alloc(tr->key, size, total); if (IS_ERR(im)) { err = PTR_ERR(im); goto out; } + im->call_orig = tr->flags & BPF_TRAMP_F_CALL_ORIG; err = arch_prepare_bpf_trampoline(im, im->image, im->image + size, &tr->func.model, tr->flags, tnodes, @@ -806,8 +816,14 @@ again: #endif out_free: - if (err) + if (err) { bpf_tramp_image_free(im); + } else { + /* track the image until it is freed, for bpf_trampoline_skip_prog() */ + refcount_inc(&tr->refcnt); + im->tr = tr; + list_add(&im->list, &tr->images); + } out: /* If any error happens, restore previous flags */ if (err) @@ -921,6 +937,41 @@ static int bpf_trampoline_add_prog(struct bpf_trampoline *tr, return 0; } +/* + * Patch the nop in front of a prog call to a jump over it. A task can be + * preempted anywhere in the image, so archs that need several instructions for + * a jump of any range patch a single near branch here instead. + */ +int __weak arch_bpf_trampoline_skip(void *nop, void *target) +{ + return bpf_arch_text_poke(nop, BPF_MOD_NOP, BPF_MOD_JUMP, NULL, target); +} + +/* + * prog was detached and can be freed, but tasks may still be running in images + * that call it, sleeping in an earlier prog for example. They can be in any + * image that is not freed yet, not only in cur_image, so patch all of them to + * jump over prog. + */ +static void bpf_trampoline_skip_prog(struct bpf_trampoline *tr, struct bpf_prog *prog) +{ + struct bpf_tramp_image *im; + int i, err; + + list_for_each_entry(im, &tr->images, list) { + for (i = 0; i < im->nr_skips; i++) { + struct bpf_tramp_skip *skip = &im->skips[i]; + + if (skip->prog != prog) + continue; + err = arch_bpf_trampoline_skip(skip->nop, skip->target); + WARN_ON_ONCE(err); + /* not a nop anymore, and prog's address can be reused */ + skip->prog = NULL; + } + } +} + static void bpf_trampoline_remove_prog(struct bpf_trampoline *tr, struct bpf_tramp_node *node) { @@ -938,6 +989,7 @@ static void bpf_trampoline_remove_prog(struct bpf_trampoline *tr, } hlist_del_init(&node->tramp_hlist); tr->progs_cnt[kind]--; + bpf_trampoline_skip_prog(tr, node->link->prog); } static int __bpf_trampoline_link_prog(struct bpf_tramp_node *node, @@ -1246,11 +1298,9 @@ void bpf_trampoline_put(struct bpf_trampoline *tr) if (WARN_ON_ONCE(!hlist_empty(&tr->progs_hlist[i]))) goto out; - /* This code will be executed even when the last bpf_tramp_image - * is alive. All progs are detached from the trampoline and the - * trampoline image is patched with jmp into epilogue to skip - * fexit progs. The fentry-only trampoline will be freed via - * multiple rcu callbacks. + /* + * All progs are detached and the last image has been freed, images + * hold a reference on the trampoline until then. */ hlist_del(&tr->hlist_key); hlist_del(&tr->hlist_ip); -- cgit v1.2.3 From e955f14fa8467d70aaeea5830b4d1773d5b25500 Mon Sep 17 00:00:00 2001 From: Zhan Xusheng Date: Mon, 28 Sep 2026 10:02:04 +0800 Subject: sysctl: Negate before converting in the int read path proc_int_k2u_conv_kop() reports the sign through *negp and the magnitude through *u_ptr, but for a negative value it hands the sign-extended int to the converter and negates the result: *u_ptr = k_ptr_op ? -k_ptr_op((ulong)val) : -(ulong)val; With div_hz() and CONFIG_HZ=1000 a stored -1000 becomes (ulong)-1000 / 1000 == 18446744073709550, and negating that wraps: # echo -1 > /proc/sys/net/ipv4/tcp_fin_timeout # cat /proc/sys/net/ipv4/tcp_fin_timeout -18428297329635842066 The magnitude is HZ dependent but the wrap is not: the negation happens after the division at every CONFIG_HZ. Take the magnitude first and convert that, which is what the open-coded version did before commit 2dc164a48e6f ("sysctl: Create converter functions with two new macros") folded it into a macro. The k_ptr_op == NULL branch was already correct. All three int converters that pass a k_ptr_op are affected: proc_dointvec_jiffies(), proc_dointvec_userhz_jiffies() and proc_dointvec_ms_jiffies(). Fixes: 2dc164a48e6f ("sysctl: Create converter functions with two new macros") Cc: stable@vger.kernel.org Reviewed-by: Bradley Morgan Signed-off-by: Zhan Xusheng Signed-off-by: Joel Granados --- kernel/sysctl.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'kernel') diff --git a/kernel/sysctl.c b/kernel/sysctl.c index f7b75985d542..38597f26b34c 100644 --- a/kernel/sysctl.c +++ b/kernel/sysctl.c @@ -483,7 +483,7 @@ int proc_int_k2u_conv_kop(ulong *u_ptr, const int *k_ptr, bool *negp, if (val < 0) { *negp = true; - *u_ptr = k_ptr_op ? -k_ptr_op((ulong)val) : -(ulong)val; + *u_ptr = k_ptr_op ? k_ptr_op(-(ulong)val) : -(ulong)val; } else { *negp = false; *u_ptr = k_ptr_op ? k_ptr_op((ulong)val) : (ulong) val; -- cgit v1.2.3 From fdd6553e1e53b0421d89c7469c8a36d2eadb1115 Mon Sep 17 00:00:00 2001 From: Zhan Xusheng Date: Mon, 28 Sep 2026 10:02:05 +0800 Subject: time/jiffies: Saturate in mult_hz() instead of wrapping Return ULONG_MAX for values that don't fit an unsigned long. proc_int_u2k_conv_uop() now correctly rejects a result above INT_MAX. This is the erroneous behaviour that is being fixed. The input has to exceed ULONG_MAX / HZ for the product to wrap, so the value below is specific to CONFIG_HZ=1000: # echo 18446744073709552 > /proc/sys/net/ipv4/tcp_keepalive_time # cat /proc/sys/net/ipv4/tcp_keepalive_time 0 That value is now rejected with an error. The original bound ("*u_ptr > INT_MAX / HZ") was removed in commit 2dc164a48e6f ("sysctl: Create converter functions with two new macros"). Fixes: 2dc164a48e6f ("sysctl: Create converter functions with two new macros") Cc: stable@vger.kernel.org Signed-off-by: Zhan Xusheng Signed-off-by: Joel Granados --- kernel/time/jiffies.c | 2 ++ 1 file changed, 2 insertions(+) (limited to 'kernel') diff --git a/kernel/time/jiffies.c b/kernel/time/jiffies.c index 80c354811538..9b3487d40cd6 100644 --- a/kernel/time/jiffies.c +++ b/kernel/time/jiffies.c @@ -101,6 +101,8 @@ void __init register_refined_jiffies(long cycles_per_second) #ifdef CONFIG_SYSCTL static ulong mult_hz(const ulong val) { + if (val >= ULONG_MAX / HZ) + return ULONG_MAX; return val * HZ; } -- cgit v1.2.3 From e0a6249190402a28f1e2925a81acf573157d55ef Mon Sep 17 00:00:00 2001 From: "Masami Hiramatsu (Google)" Date: Tue, 29 Sep 2026 09:19:12 +0900 Subject: fprobe: Use guard(rcu_sched_notrace) and check rcu_is_watching() unregister_fprobe() and unregister_fprobe_async() (used by BPF kprobe-multi) rely on standard RCU grace periods (synchronize_rcu() and call_rcu()) to wait until in-flight fprobe handlers complete before freeing the fprobe. However, if an fprobe handler executes while RCU is not watching (such as in the idle loop or nohz_full extended quiescent states), standard RCU does not track preemption-disabled sections. Consequently, synchronize_rcu() does not wait for those executions, which can lead to a use-after-free if the fprobe is freed immediately after unregistration. Ensure handlers exit early when !rcu_is_watching(). Furthermore, fprobe_fgraph_entry() and fprobe_ftrace_entry() previously used guard(rcu)() and rcu_read_lock(), which invoke lockdep on every hit under CONFIG_PROVE_LOCKING. This adds overhead and can cause lockdep recursion if probed functions interact with lockdep. Since rhltable_lookup() and rhl_for_each_entry_rcu() use rcu_dereference_all_check() (which checks rcu_read_lock_any_held()), holding preemption disabled via rcu_read_lock_sched_notrace() is fully valid and sufficient so long as rcu_is_watching() is true. Define and use guard(rcu_sched_notrace)() across fprobe_ftrace_entry(), fprobe_fgraph_entry(), and fprobe_return(). This eliminates fast-path rcu_read_lock() and lockdep overhead while guaranteeing safe grace period synchronization. Link: https://lore.kernel.org/all/179064115227.394389.16910234241400391996.stgit@devnote2/ Reported-by: Sashiko Closes: https://sashiko.dev/#/bug/linux-e46bcd68-4a56-4f19-a255-e3772980e5e3 Fixes: 657b594b2084 ("fprobe: Fix unregister_fprobe() to wait for RCU grace period") Cc: stable@vger.kernel.org Assisted-by: LLM Signed-off-by: Masami Hiramatsu (Google) Reviewed-by: Paul E. McKenney --- kernel/trace/fprobe.c | 26 ++++++++++++++++---------- 1 file changed, 16 insertions(+), 10 deletions(-) (limited to 'kernel') diff --git a/kernel/trace/fprobe.c b/kernel/trace/fprobe.c index 9f2d98181779..da286619c5d8 100644 --- a/kernel/trace/fprobe.c +++ b/kernel/trace/fprobe.c @@ -47,6 +47,10 @@ static struct rhltable fprobe_ip_table; static DEFINE_MUTEX(fprobe_mutex); static struct fgraph_ops fprobe_graph_ops; +DEFINE_LOCK_GUARD_0(rcu_sched_notrace, + rcu_read_lock_sched_notrace(), + rcu_read_unlock_sched_notrace()) + static u32 fprobe_node_hashfn(const void *data, u32 len, u32 seed) { return hash_ptr(*(unsigned long **)data, 32); @@ -329,16 +333,14 @@ static void fprobe_ftrace_entry(unsigned long ip, unsigned long parent_ip, struct fprobe *fp; int bit; + if (!rcu_is_watching()) + return; + bit = ftrace_test_recursion_trylock(ip, parent_ip); if (bit < 0) return; - /* - * ftrace_test_recursion_trylock() disables preemption, but - * rhltable_lookup() checks whether rcu_read_lcok is held. - * So we take rcu_read_lock() here. - */ - rcu_read_lock(); + guard(rcu_sched_notrace)(); head = rhltable_lookup(&fprobe_ip_table, &ip, fprobe_rht_params); rhl_for_each_entry_rcu(node, pos, head, hlist) { @@ -353,7 +355,6 @@ static void fprobe_ftrace_entry(unsigned long ip, unsigned long parent_ip, else __fprobe_handler(ip, parent_ip, fp, fregs, NULL); } - rcu_read_unlock(); ftrace_test_recursion_unlock(bit); } NOKPROBE_SYMBOL(fprobe_ftrace_entry); @@ -567,10 +568,13 @@ static int fprobe_fgraph_entry(struct ftrace_graph_ent *trace, struct fgraph_ops struct fprobe *fp; int used, ret; + if (!rcu_is_watching()) + return 0; + if (WARN_ON_ONCE(!fregs)) return 0; - guard(rcu)(); + guard(rcu_sched_notrace)(); head = rhltable_lookup(&fprobe_ip_table, &func, fprobe_rht_params); reserved_words = 0; rhl_for_each_entry_rcu(node, pos, head, hlist) { @@ -665,13 +669,16 @@ static void fprobe_return(struct ftrace_graph_ret *trace, int size, curr; int size_words; + if (!rcu_is_watching()) + return; + fgraph_data = (unsigned long *)fgraph_retrieve_data(gops->idx, &size); if (WARN_ON_ONCE(!fgraph_data)) return; size_words = SIZE_IN_LONG(size); ret_ip = ftrace_regs_get_instruction_pointer(fregs); - preempt_disable_notrace(); + guard(rcu_sched_notrace)(); curr = 0; while (size_words > curr) { @@ -687,7 +694,6 @@ static void fprobe_return(struct ftrace_graph_ret *trace, } curr += size; } - preempt_enable_notrace(); } NOKPROBE_SYMBOL(fprobe_return); -- cgit v1.2.3 From ffb684f2aa141eeb0caa6308422e7e05d1ded7c4 Mon Sep 17 00:00:00 2001 From: Luo Gengkun Date: Sun, 20 Sep 2026 07:50:26 +0000 Subject: perf: Fix race between perf_event_exit_task() and perf_pending_task() A race condition exists between perf_event_exit_task() and perf_pending_task() during begin_new_exec(). During begin_new_exec(), perf_event_exit_task() may be called, and the PF_EXITING flag is not set on task. So perf_sigtrap() continues to execute and triggers WARN_ON_ONCE(event->ctx->task != current). Since both task exit and exec paths can call perf_event_exit_task() which sets ctx->task to TASK_TOMBSTONE, fix this by explicitly checking if event->ctx->task equals TASK_TOMBSTONE and dropping the redundant PF_EXITING check. Fixes: 97ba62b27867 ("perf: Add support for SIGTRAP on perf events") Signed-off-by: Luo Gengkun Signed-off-by: Peter Zijlstra (Intel) Link: https://patch.msgid.link/20260920075026.990582-1-luogengkun2@huawei.com --- kernel/events/core.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) (limited to 'kernel') diff --git a/kernel/events/core.c b/kernel/events/core.c index 634d2ccbab82..c2882b5be7c3 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -7626,9 +7626,11 @@ static void perf_sigtrap(struct perf_event *event) { /* * Both perf_pending_task() and perf_pending_irq() can race with the - * task exiting. + * task exiting or exec-ing. We can determine if such a race has + * occurred by checking if perf_event_exit_task(), which will set + * ctx->task to TASK_TOMBSTONE, has already been called. */ - if (current->flags & PF_EXITING) + if (event->ctx->task == TASK_TOMBSTONE) return; /* -- cgit v1.2.3 From b9d1fdc6f4ac1b6e49f9deafaf137da1407d9af1 Mon Sep 17 00:00:00 2001 From: Ian Rogers Date: Tue, 29 Sep 2026 15:23:32 -0700 Subject: perf: Replace perf_event_header__init_id with full header init perf_iterate_sb() invokes its callback for each matching perf_event on the CPU and task context, passing a shared caller-allocated event structure. perf_event_header__init_id() mutated header->size in place by adding event->id_header_size, requiring sideband output callbacks to save and restore header fields across iterations. Three sideband callbacks failed to save and restore header.size around perf_event_header__init_id(): - perf_event_ksymbol_output() - perf_event_bpf_output() - perf_event_text_poke_output() When multiple events with attr.ksymbol, attr.bpf_event, or attr.text_poke and sample_id_all are active on the same CPU, each subsequent event receives a record whose header.size is inflated by all preceding events' id_header_size values while only a single id_sample is written, leaving uninitialized ring-buffer bytes at the end of the record and causing userspace perf to fail with -EFAULT ("Bad address") when parsing the sample_id trailer. Similarly, perf_event_mmap_output() set PERF_RECORD_MISC_MMAP_BUILD_ID in mmap_event->event_id.header.misc when event->attr.build_id was enabled, but only saved and restored header.size and header.type. If an event with attr.build_id was followed by an event with attr.mmap2 and !attr.build_id, the second event received PERF_RECORD_MISC_MMAP_BUILD_ID in header.misc while its payload contained maj/min/ino/ino_generation instead of a build ID. Rather than splitting header initialization between callers and output callbacks and saving/restoring mutated header fields, replace perf_event_header__init_id() with perf_event_header__init(), which initializes header->type, header->misc, and header->size alongside the sample_id fields on each invocation. Fixes: 76193a94522f ("perf, bpf: Introduce PERF_RECORD_KSYMBOL") Fixes: 6ee52e2a3fe4 ("perf, bpf: Introduce PERF_RECORD_BPF_EVENT") Fixes: e17d43b93e54 ("perf: Add perf text poke event") Fixes: 88a16a130933 ("perf: Add build id data in mmap2 event") Assisted-by: Antigravity:gemini-3.1-pro Signed-off-by: Ian Rogers Signed-off-by: Peter Zijlstra (Intel) Link: https://patch.msgid.link/20260929222332.973435-1-irogers@google.com Cc: stable@vger.kernel.org --- kernel/events/core.c | 307 +++++++++++++++++++------------------------- kernel/events/ring_buffer.c | 7 +- 2 files changed, 132 insertions(+), 182 deletions(-) (limited to 'kernel') diff --git a/kernel/events/core.c b/kernel/events/core.c index c2882b5be7c3..3aa223595e7d 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -8131,10 +8131,15 @@ static void __perf_event_header__init_id(struct perf_sample_data *data, } } -void perf_event_header__init_id(struct perf_event_header *header, - struct perf_sample_data *data, - struct perf_event *event) +void perf_event_header__init(struct perf_event_header *header, + struct perf_sample_data *data, + u32 type, u16 misc, u16 size, + struct perf_event *event) { + header->type = type; + header->misc = misc; + header->size = size; + if (event->attr.sample_id_all) { header->size += event->id_header_size; __perf_event_header__init_id(data, event, event->attr.sample_type); @@ -8971,17 +8976,16 @@ perf_event_read_event(struct perf_event *event, struct perf_output_handle handle; struct perf_sample_data sample; struct perf_read_event read_event = { - .header = { - .type = PERF_RECORD_READ, - .misc = 0, - .size = sizeof(read_event) + event->read_size, - }, .pid = perf_event_pid(event, task), .tid = perf_event_tid(event, task), }; int ret; - perf_event_header__init_id(&read_event.header, &sample, event); + perf_event_header__init(&read_event.header, &sample, + PERF_RECORD_READ, + /* misc= */ 0, + sizeof(read_event) + event->read_size, + event); ret = perf_output_begin(&handle, &sample, event, read_event.header.size); if (ret) return; @@ -9222,6 +9226,7 @@ struct perf_task_event { u32 ptid; u64 time; } event_id; + int new; }; static int perf_event_task_match(struct perf_event *event) @@ -9238,17 +9243,21 @@ static void perf_event_task_output(struct perf_event *event, struct perf_output_handle handle; struct perf_sample_data sample; struct task_struct *task = task_event->task; - int ret, size = task_event->event_id.header.size; + int ret; if (!perf_event_task_match(event)) return; - perf_event_header__init_id(&task_event->event_id.header, &sample, event); + perf_event_header__init(&task_event->event_id.header, &sample, + task_event->new ? PERF_RECORD_FORK : PERF_RECORD_EXIT, + /* misc= */ 0, + sizeof(task_event->event_id), + event); ret = perf_output_begin(&handle, &sample, event, task_event->event_id.header.size); if (ret) - goto out; + return; task_event->event_id.pid = perf_event_pid(event, task); task_event->event_id.tid = perf_event_tid(event, task); @@ -9270,8 +9279,6 @@ static void perf_event_task_output(struct perf_event *event, perf_event__output_id_sample(event, &handle, &sample); perf_output_end(&handle); -out: - task_event->event_id.header.size = size; } static void perf_event_task(struct task_struct *task, @@ -9288,18 +9295,7 @@ static void perf_event_task(struct task_struct *task, task_event = (struct perf_task_event){ .task = task, .task_ctx = task_ctx, - .event_id = { - .header = { - .type = new ? PERF_RECORD_FORK : PERF_RECORD_EXIT, - .misc = 0, - .size = sizeof(task_event.event_id), - }, - /* .pid */ - /* .ppid */ - /* .tid */ - /* .ptid */ - /* .time */ - }, + .new = new, }; perf_iterate_sb(perf_event_task_output, @@ -9376,6 +9372,7 @@ struct perf_comm_event { u32 pid; u32 tid; } event_id; + bool exec; }; static int perf_event_comm_match(struct perf_event *event) @@ -9389,18 +9386,21 @@ static void perf_event_comm_output(struct perf_event *event, struct perf_comm_event *comm_event = data; struct perf_output_handle handle; struct perf_sample_data sample; - int size = comm_event->event_id.header.size; int ret; if (!perf_event_comm_match(event)) return; - perf_event_header__init_id(&comm_event->event_id.header, &sample, event); + perf_event_header__init(&comm_event->event_id.header, &sample, + PERF_RECORD_COMM, + comm_event->exec ? PERF_RECORD_MISC_COMM_EXEC : 0, + sizeof(comm_event->event_id) + comm_event->comm_size, + event); ret = perf_output_begin(&handle, &sample, event, comm_event->event_id.header.size); if (ret) - goto out; + return; comm_event->event_id.pid = perf_event_pid(event, comm_event->task); comm_event->event_id.tid = perf_event_tid(event, comm_event->task); @@ -9412,8 +9412,6 @@ static void perf_event_comm_output(struct perf_event *event, perf_event__output_id_sample(event, &handle, &sample); perf_output_end(&handle); -out: - comm_event->event_id.header.size = size; } static void perf_event_comm_event(struct perf_comm_event *comm_event) @@ -9428,8 +9426,6 @@ static void perf_event_comm_event(struct perf_comm_event *comm_event) comm_event->comm = comm; comm_event->comm_size = size; - comm_event->event_id.header.size = sizeof(comm_event->event_id) + size; - perf_iterate_sb(perf_event_comm_output, comm_event, NULL); @@ -9446,15 +9442,8 @@ void perf_event_comm(struct task_struct *task, bool exec) .task = task, /* .comm */ /* .comm_size */ - .event_id = { - .header = { - .type = PERF_RECORD_COMM, - .misc = exec ? PERF_RECORD_MISC_COMM_EXEC : 0, - /* .size */ - }, - /* .pid */ - /* .tid */ - }, + /* .event_id */ + .exec = exec, }; perf_event_comm_event(&comm_event); @@ -9488,18 +9477,20 @@ static void perf_event_namespaces_output(struct perf_event *event, struct perf_namespaces_event *namespaces_event = data; struct perf_output_handle handle; struct perf_sample_data sample; - u16 header_size = namespaces_event->event_id.header.size; int ret; if (!perf_event_namespaces_match(event)) return; - perf_event_header__init_id(&namespaces_event->event_id.header, - &sample, event); + perf_event_header__init(&namespaces_event->event_id.header, &sample, + PERF_RECORD_NAMESPACES, + /* misc= */ 0, + sizeof(namespaces_event->event_id), + event); ret = perf_output_begin(&handle, &sample, event, namespaces_event->event_id.header.size); if (ret) - goto out; + return; namespaces_event->event_id.pid = perf_event_pid(event, namespaces_event->task); @@ -9511,8 +9502,6 @@ static void perf_event_namespaces_output(struct perf_event *event, perf_event__output_id_sample(event, &handle, &sample); perf_output_end(&handle); -out: - namespaces_event->event_id.header.size = header_size; } static void perf_fill_ns_link_info(struct perf_ns_link_info *ns_link_info, @@ -9543,11 +9532,7 @@ void perf_event_namespaces(struct task_struct *task) namespaces_event = (struct perf_namespaces_event){ .task = task, .event_id = { - .header = { - .type = PERF_RECORD_NAMESPACES, - .misc = 0, - .size = sizeof(namespaces_event.event_id), - }, + /* .header */ /* .pid */ /* .tid */ .nr_namespaces = NR_NAMESPACES, @@ -9615,18 +9600,19 @@ static void perf_event_cgroup_output(struct perf_event *event, void *data) struct perf_cgroup_event *cgroup_event = data; struct perf_output_handle handle; struct perf_sample_data sample; - u16 header_size = cgroup_event->event_id.header.size; int ret; + u16 size = sizeof(cgroup_event->event_id) + cgroup_event->path_size; if (!perf_event_cgroup_match(event)) return; - perf_event_header__init_id(&cgroup_event->event_id.header, - &sample, event); + perf_event_header__init(&cgroup_event->event_id.header, &sample, + PERF_RECORD_CGROUP, /* misc= */ 0, size, + event); ret = perf_output_begin(&handle, &sample, event, cgroup_event->event_id.header.size); if (ret) - goto out; + return; perf_output_put(&handle, cgroup_event->event_id); __output_copy(&handle, cgroup_event->path, cgroup_event->path_size); @@ -9634,8 +9620,6 @@ static void perf_event_cgroup_output(struct perf_event *event, void *data) perf_event__output_id_sample(event, &handle, &sample); perf_output_end(&handle); -out: - cgroup_event->event_id.header.size = header_size; } static void perf_event_cgroup(struct cgroup *cgrp) @@ -9650,11 +9634,6 @@ static void perf_event_cgroup(struct cgroup *cgrp) cgroup_event = (struct perf_cgroup_event){ .event_id = { - .header = { - .type = PERF_RECORD_CGROUP, - .misc = 0, - .size = sizeof(cgroup_event.event_id), - }, .id = cgroup_id(cgrp), }, }; @@ -9677,7 +9656,6 @@ static void perf_event_cgroup(struct cgroup *cgrp) while (!IS_ALIGNED(size, sizeof(u64))) cgroup_event.path[size++] = '\0'; - cgroup_event.event_id.header.size += size; cgroup_event.path_size = size; perf_iterate_sb(perf_event_cgroup_output, @@ -9733,38 +9711,40 @@ static void perf_event_mmap_output(struct perf_event *event, struct perf_mmap_event *mmap_event = data; struct perf_output_handle handle; struct perf_sample_data sample; - int size = mmap_event->event_id.header.size; - u32 type = mmap_event->event_id.header.type; - bool use_build_id; + int size = sizeof(mmap_event->event_id) + mmap_event->file_size; + u32 type = PERF_RECORD_MMAP; + u16 misc = PERF_RECORD_MISC_USER; + bool use_build_id = false; int ret; if (!perf_event_mmap_match(event, data)) return; if (event->attr.mmap2) { - mmap_event->event_id.header.type = PERF_RECORD_MMAP2; - mmap_event->event_id.header.size += sizeof(mmap_event->maj); - mmap_event->event_id.header.size += sizeof(mmap_event->min); - mmap_event->event_id.header.size += sizeof(mmap_event->ino); - mmap_event->event_id.header.size += sizeof(mmap_event->ino_generation); - mmap_event->event_id.header.size += sizeof(mmap_event->prot); - mmap_event->event_id.header.size += sizeof(mmap_event->flags); - } - - perf_event_header__init_id(&mmap_event->event_id.header, &sample, event); + type = PERF_RECORD_MMAP2; + size += sizeof(mmap_event->maj); + size += sizeof(mmap_event->min); + size += sizeof(mmap_event->ino); + size += sizeof(mmap_event->ino_generation); + size += sizeof(mmap_event->prot); + size += sizeof(mmap_event->flags); + use_build_id = event->attr.build_id && mmap_event->build_id_size; + if (use_build_id) + misc |= PERF_RECORD_MISC_MMAP_BUILD_ID; + } + if (!(mmap_event->vma->vm_flags & VM_EXEC)) + misc |= PERF_RECORD_MISC_MMAP_DATA; + + perf_event_header__init(&mmap_event->event_id.header, &sample, + type, misc, size, event); ret = perf_output_begin(&handle, &sample, event, mmap_event->event_id.header.size); if (ret) - goto out; + return; mmap_event->event_id.pid = perf_event_pid(event, current); mmap_event->event_id.tid = perf_event_tid(event, current); - use_build_id = event->attr.build_id && mmap_event->build_id_size; - - if (event->attr.mmap2 && use_build_id) - mmap_event->event_id.header.misc |= PERF_RECORD_MISC_MMAP_BUILD_ID; - perf_output_put(&handle, mmap_event->event_id); if (event->attr.mmap2) { @@ -9789,9 +9769,6 @@ static void perf_event_mmap_output(struct perf_event *event, perf_event__output_id_sample(event, &handle, &sample); perf_output_end(&handle); -out: - mmap_event->event_id.header.size = size; - mmap_event->event_id.header.type = type; } static void perf_event_mmap_event(struct perf_mmap_event *mmap_event) @@ -9887,11 +9864,6 @@ got_name: mmap_event->prot = prot; mmap_event->flags = flags; - if (!(vma->vm_flags & VM_EXEC)) - mmap_event->event_id.header.misc |= PERF_RECORD_MISC_MMAP_DATA; - - mmap_event->event_id.header.size = sizeof(mmap_event->event_id) + size; - if (atomic_read(&nr_build_id_events)) build_id_parse_nofault(vma, mmap_event->build_id, &mmap_event->build_id_size); @@ -10011,11 +9983,7 @@ void perf_event_mmap(struct vm_area_struct *vma) /* .file_name */ /* .file_size */ .event_id = { - .header = { - .type = PERF_RECORD_MMAP, - .misc = PERF_RECORD_MISC_USER, - /* .size */ - }, + /* .header */ /* .pid */ /* .tid */ .start = vma->vm_start, @@ -10045,18 +10013,15 @@ void perf_event_aux_event(struct perf_event *event, unsigned long head, u64 size; u64 flags; } rec = { - .header = { - .type = PERF_RECORD_AUX, - .misc = 0, - .size = sizeof(rec), - }, .offset = head, .size = size, .flags = flags, }; int ret; - perf_event_header__init_id(&rec.header, &sample, event); + perf_event_header__init(&rec.header, &sample, + PERF_RECORD_AUX, /* misc= */ 0, sizeof(rec), + event); ret = perf_output_begin(&handle, &sample, event, rec.header.size); if (ret) @@ -10081,15 +10046,14 @@ void perf_log_lost_samples(struct perf_event *event, u64 lost) struct perf_event_header header; u64 lost; } lost_samples_event = { - .header = { - .type = PERF_RECORD_LOST_SAMPLES, - .misc = 0, - .size = sizeof(lost_samples_event), - }, .lost = lost, }; - perf_event_header__init_id(&lost_samples_event.header, &sample, event); + perf_event_header__init(&lost_samples_event.header, &sample, + PERF_RECORD_LOST_SAMPLES, + /* misc= */ 0, + sizeof(lost_samples_event), + event); ret = perf_output_begin(&handle, &sample, event, lost_samples_event.header.size); @@ -10114,6 +10078,8 @@ struct perf_switch_event { u32 next_prev_pid; u32 next_prev_tid; } event_id; + bool sched_in; + bool preempt; }; static int perf_event_switch_match(struct perf_event *event) @@ -10126,6 +10092,9 @@ static void perf_event_switch_output(struct perf_event *event, void *data) struct perf_switch_event *se = data; struct perf_output_handle handle; struct perf_sample_data sample; + u32 type; + u16 misc; + u16 size; int ret; if (!perf_event_switch_match(event)) @@ -10133,18 +10102,22 @@ static void perf_event_switch_output(struct perf_event *event, void *data) /* Only CPU-wide events are allowed to see next/prev pid/tid */ if (event->ctx->task) { - se->event_id.header.type = PERF_RECORD_SWITCH; - se->event_id.header.size = sizeof(se->event_id.header); + type = PERF_RECORD_SWITCH; + size = sizeof(se->event_id.header); } else { - se->event_id.header.type = PERF_RECORD_SWITCH_CPU_WIDE; - se->event_id.header.size = sizeof(se->event_id); + type = PERF_RECORD_SWITCH_CPU_WIDE; + size = sizeof(se->event_id); se->event_id.next_prev_pid = perf_event_pid(event, se->next_prev); se->event_id.next_prev_tid = perf_event_tid(event, se->next_prev); } + misc = se->sched_in ? 0 : PERF_RECORD_MISC_SWITCH_OUT; + if (se->preempt) + misc |= PERF_RECORD_MISC_SWITCH_OUT_PREEMPT; - perf_event_header__init_id(&se->event_id.header, &sample, event); + perf_event_header__init(&se->event_id.header, &sample, + type, misc, size, event); ret = perf_output_begin(&handle, &sample, event, se->event_id.header.size); if (ret) @@ -10170,22 +10143,11 @@ static void perf_event_switch(struct task_struct *task, switch_event = (struct perf_switch_event){ .task = task, .next_prev = next_prev, - .event_id = { - .header = { - /* .type */ - .misc = sched_in ? 0 : PERF_RECORD_MISC_SWITCH_OUT, - /* .size */ - }, - /* .next_prev_pid */ - /* .next_prev_tid */ - }, + /* .event_id */ + .sched_in = sched_in, + .preempt = !sched_in && task_is_runnable(task), }; - if (!sched_in && task_is_runnable(task)) { - switch_event.event_id.header.misc |= - PERF_RECORD_MISC_SWITCH_OUT_PREEMPT; - } - perf_iterate_sb(perf_event_switch_output, &switch_event, NULL); } @@ -10205,20 +10167,17 @@ static void perf_log_throttle(struct perf_event *event, int enable) u64 id; u64 stream_id; } throttle_event = { - .header = { - .type = PERF_RECORD_THROTTLE, - .misc = 0, - .size = sizeof(throttle_event), - }, .time = perf_event_clock(event), .id = primary_event_id(event), .stream_id = event->id, }; - if (enable) - throttle_event.header.type = PERF_RECORD_UNTHROTTLE; - - perf_event_header__init_id(&throttle_event.header, &sample, event); + perf_event_header__init(&throttle_event.header, &sample, + enable ? PERF_RECORD_UNTHROTTLE + : PERF_RECORD_THROTTLE, + /* misc= */ 0, + sizeof(throttle_event), + event); ret = perf_output_begin(&handle, &sample, event, throttle_event.header.size); @@ -10257,12 +10216,14 @@ static void perf_event_ksymbol_output(struct perf_event *event, void *data) struct perf_output_handle handle; struct perf_sample_data sample; int ret; + u16 size = sizeof(ksymbol_event->event_id) + ksymbol_event->name_len; if (!perf_event_ksymbol_match(event)) return; - perf_event_header__init_id(&ksymbol_event->event_id.header, - &sample, event); + perf_event_header__init(&ksymbol_event->event_id.header, &sample, + PERF_RECORD_KSYMBOL, /* misc= */ 0, size, + event); ret = perf_output_begin(&handle, &sample, event, ksymbol_event->event_id.header.size); if (ret) @@ -10303,11 +10264,6 @@ void perf_event_ksymbol(u16 ksym_type, u64 addr, u32 len, bool unregister, .name = name, .name_len = name_len, .event_id = { - .header = { - .type = PERF_RECORD_KSYMBOL, - .size = sizeof(ksymbol_event.event_id) + - name_len, - }, .addr = addr, .len = len, .ksym_type = ksym_type, @@ -10351,8 +10307,11 @@ static void perf_event_bpf_output(struct perf_event *event, void *data) if (!perf_event_bpf_match(event)) return; - perf_event_header__init_id(&bpf_event->event_id.header, - &sample, event); + perf_event_header__init(&bpf_event->event_id.header, &sample, + PERF_RECORD_BPF_EVENT, + /* misc= */ 0, + sizeof(bpf_event->event_id), + event); ret = perf_output_begin(&handle, &sample, event, bpf_event->event_id.header.size); if (ret) @@ -10408,10 +10367,6 @@ void perf_event_bpf_event(struct bpf_prog *prog, bpf_event = (struct perf_bpf_event){ .prog = prog, .event_id = { - .header = { - .type = PERF_RECORD_BPF_EVENT, - .size = sizeof(bpf_event.event_id), - }, .type = type, .flags = flags, .id = prog->aux->id, @@ -10439,18 +10394,23 @@ static void perf_callchain_deferred_output(struct perf_event *event, void *data) struct perf_callchain_deferred_event *deferred_event = data; struct perf_output_handle handle; struct perf_sample_data sample; - int ret, size = deferred_event->event.header.size; + int ret; + u16 size = sizeof(deferred_event->event) + (deferred_event->trace->nr * sizeof(u64)); if (!event->attr.defer_output) return; /* XXX do we really need sample_id_all for this ??? */ - perf_event_header__init_id(&deferred_event->event.header, &sample, event); + perf_event_header__init(&deferred_event->event.header, &sample, + PERF_RECORD_CALLCHAIN_DEFERRED, + PERF_RECORD_MISC_USER, + size, + event); ret = perf_output_begin(&handle, &sample, event, deferred_event->event.header.size); if (ret) - goto out; + return; perf_output_put(&handle, deferred_event->event); for (int i = 0; i < deferred_event->trace->nr; i++) { @@ -10460,8 +10420,6 @@ static void perf_callchain_deferred_output(struct perf_event *event, void *data) perf_event__output_id_sample(event, &handle, &sample); perf_output_end(&handle); -out: - deferred_event->event.header.size = size; } static void perf_unwind_deferred_callback(struct unwind_work *work, @@ -10470,12 +10428,6 @@ static void perf_unwind_deferred_callback(struct unwind_work *work, struct perf_callchain_deferred_event deferred_event = { .trace = trace, .event = { - .header = { - .type = PERF_RECORD_CALLCHAIN_DEFERRED, - .misc = PERF_RECORD_MISC_USER, - .size = sizeof(deferred_event.event) + - (trace->nr * sizeof(u64)), - }, .cookie = cookie, .nr = trace->nr, }, @@ -10487,7 +10439,8 @@ static void perf_unwind_deferred_callback(struct unwind_work *work, struct perf_text_poke_event { const void *old_bytes; const void *new_bytes; - size_t pad; + u16 tot; + u16 pad; u16 old_len; u16 new_len; @@ -10508,13 +10461,18 @@ static void perf_event_text_poke_output(struct perf_event *event, void *data) struct perf_text_poke_event *text_poke_event = data; struct perf_output_handle handle; struct perf_sample_data sample; + u16 size = sizeof(text_poke_event->event_id) + text_poke_event->tot + text_poke_event->pad; u64 padding = 0; int ret; if (!perf_event_text_poke_match(event)) return; - perf_event_header__init_id(&text_poke_event->event_id.header, &sample, event); + perf_event_header__init(&text_poke_event->event_id.header, &sample, + PERF_RECORD_TEXT_POKE, + PERF_RECORD_MISC_KERNEL, + size, + event); ret = perf_output_begin(&handle, &sample, event, text_poke_event->event_id.header.size); @@ -10552,15 +10510,11 @@ void perf_event_text_poke(const void *addr, const void *old_bytes, text_poke_event = (struct perf_text_poke_event){ .old_bytes = old_bytes, .new_bytes = new_bytes, + .tot = tot, .pad = pad, .old_len = old_len, .new_len = new_len, .event_id = { - .header = { - .type = PERF_RECORD_TEXT_POKE, - .misc = PERF_RECORD_MISC_KERNEL, - .size = sizeof(text_poke_event.event_id) + tot + pad, - }, .addr = (unsigned long)addr, }, }; @@ -10591,13 +10545,12 @@ static void perf_log_itrace_start(struct perf_event *event) event->attach_state & PERF_ATTACH_ITRACE) return; - rec.header.type = PERF_RECORD_ITRACE_START; - rec.header.misc = 0; - rec.header.size = sizeof(rec); rec.pid = perf_event_pid(event, current); rec.tid = perf_event_tid(event, current); - perf_event_header__init_id(&rec.header, &sample, event); + perf_event_header__init(&rec.header, &sample, + PERF_RECORD_ITRACE_START, /* misc= */ 0, sizeof(rec), + event); ret = perf_output_begin(&handle, &sample, event, rec.header.size); if (ret) @@ -10622,12 +10575,10 @@ void perf_report_aux_output_id(struct perf_event *event, u64 hw_id) if (event->parent) event = event->parent; - rec.header.type = PERF_RECORD_AUX_OUTPUT_HW_ID; - rec.header.misc = 0; - rec.header.size = sizeof(rec); - rec.hw_id = hw_id; - - perf_event_header__init_id(&rec.header, &sample, event); + rec.hw_id = hw_id; + perf_event_header__init(&rec.header, &sample, + PERF_RECORD_AUX_OUTPUT_HW_ID, /* misc= */ 0, + sizeof(rec), event); ret = perf_output_begin(&handle, &sample, event, rec.header.size); if (ret) diff --git a/kernel/events/ring_buffer.c b/kernel/events/ring_buffer.c index 1b1ffe0533e5..13bd42e5493d 100644 --- a/kernel/events/ring_buffer.c +++ b/kernel/events/ring_buffer.c @@ -246,14 +246,13 @@ __perf_output_begin(struct perf_output_handle *handle, handle->size = (1UL << page_shift) - offset; if (unlikely(have_lost)) { - lost_event.header.size = sizeof(lost_event); - lost_event.header.type = PERF_RECORD_LOST; - lost_event.header.misc = 0; lost_event.id = event->id; lost_event.lost = local_xchg(&rb->lost, 0); /* XXX mostly redundant; @data is already fully initializes */ - perf_event_header__init_id(&lost_event.header, data, event); + perf_event_header__init(&lost_event.header, data, + PERF_RECORD_LOST, /* misc= */ 0, + sizeof(lost_event), event); perf_output_put(handle, lost_event); perf_event__output_id_sample(event, handle, data); } -- cgit v1.2.3 From 357e8a77a501d96c9517f01f4a211eed5e9c9184 Mon Sep 17 00:00:00 2001 From: Zhengchuan Liang Date: Mon, 28 Sep 2026 10:59:35 -0700 Subject: perf: Require kernel access for text poke events Perf events with exclude_kernel=1 can be opened without kernel perf access. However, exclude_kernel does not suppress text-poke sideband records. Every PERF_RECORD_TEXT_POKE is marked PERF_RECORD_MISC_KERNEL and contains a raw kernel instruction address. An unprivileged task can therefore open and mmap a task-local software event with text_poke=1. Both opening a count-only tracepoint event and configuring UDP GRO for ESP-in-UDP cause updates to inline static calls; the observer receives the relocated addresses of the modified instructions. For a known kernel image, any such address reveals the runtime kernel text base despite KASLR. Call perf_allow_kernel() whenever attr.text_poke is set, regardless of exclude_kernel. Events that neither monitor kernel execution nor request text-poke records retain their existing permissions. Fixes: e17d43b93e54 ("perf: Add perf text poke event") Assisted-by: LLM Signed-off-by: Zhengchuan Liang Signed-off-by: Peter Zijlstra (Intel) Cc: stable@vger.kernel.org Link: https://patch.msgid.link/99131354c41e23188f778b92f90363775b482395.1790573390.git.zcliangcn@gmail.com --- kernel/events/core.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'kernel') diff --git a/kernel/events/core.c b/kernel/events/core.c index 3aa223595e7d..7846d70be57f 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -13906,7 +13906,7 @@ SYSCALL_DEFINE5(perf_event_open, if (err) return err; - if (!attr.exclude_kernel || + if (!attr.exclude_kernel || attr.text_poke || ((attr.sample_type & PERF_SAMPLE_CALLCHAIN) && !attr.exclude_callchain_kernel)) { err = perf_allow_kernel(); -- cgit v1.2.3 From b88822d2584f78cbdad1d8256510dcac108b5630 Mon Sep 17 00:00:00 2001 From: Alexei Starovoitov Date: Thu, 1 Oct 2026 14:52:54 +0000 Subject: bpf: Fix packet range of pointers sharing an id Since commit 022ac0750883 ("bpf: use reg->var_off instead of reg->off for pointers"), find_good_pkt_pointers() sets the range of all packet pointers sharing an id from the umax of the compared pointer, and check_packet_access() requires umax + off + size <= range. That assumes the umax of two such pointers differ by exactly their constant distance. reg_bounds_sync() breaks it when var_off tightens one umax and not the other: r4 &= 0x38 if r4 > 50 goto exit ; umax 50, var_off (0x0; 0x38) r5 = pkt + r4 ; umax 50 r6 = r5 r6 += 8 ; umax 56, not 58 Comparing r6 with pkt_end sets the range to 56, and the valid 8-byte load at r5 is rejected (50 + 8 > 56). Comparing r5 sets it to 50, and the out-of-bounds 1-byte load at r6 - 7, i.e. r5 + 1, is accepted (56 - 7 + 1 <= 50). Don't call reg_bounds_sync() on a packet pointer that keeps its id (a constant was added or subtracted) or its range (an unknown non-negative value was subtracted), so that var_off cannot tighten its umax. Only update the 32-bit bounds from var_off: reg_bounds_sanity_check() wants them constant when the lower half of var_off is, e.g. for pkt + 8. This relies on nothing else changing the 64-bit bounds of a packet pointer, which holds today. var_off of such a pointer is no longer narrowed by its bounds. Adjust three verifier_align expectations; the low bits, which the alignment checks use, don't change. veristat on the selftests shows no verdict changes and +0.8% insns in test_cls_redirect_subprogs. Fixes: 022ac0750883 ("bpf: use reg->var_off instead of reg->off for pointers") Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/20261001145255.855630-1-alexei.starovoitov@gmail.com Signed-off-by: Kumar Kartikeya Dwivedi --- kernel/bpf/verifier.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) (limited to 'kernel') diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 41b49c56e123..5f874979b8d7 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -14826,7 +14826,15 @@ static int adjust_ptr_min_max_vals(struct bpf_verifier_env *env, struct bpf_insn "Tighten the scalar bounds before the arithmetic so the resulting pointer remains within the allowed range."); return -EINVAL; } - reg_bounds_sync(dst_reg); + /* + * A packet pointer that keeps its id or range is checked against a + * range set from the checked pointer's umax, so var_off must not tighten + * its umax. r32 must still match var_off for reg_bounds_sanity_check(). + */ + if (reg_is_pkt_pointer(dst_reg) && (known || dst_reg->range > 0)) + __update_reg32_bounds(dst_reg); + else + reg_bounds_sync(dst_reg); bounds_ret = sanitize_check_bounds(env, insn, dst_reg); if (bounds_ret == -EACCES) return bounds_ret; -- cgit v1.2.3 From 47f4f695cec1eb82d961fdb466cd7c99d2865b7c Mon Sep 17 00:00:00 2001 From: Alexei Starovoitov Date: Wed, 30 Sep 2026 09:59:18 +0000 Subject: bpf: Factor out __do_call_rcu_ttrace() Move the part of do_call_rcu_ttrace() that runs after call_rcu_ttrace_in_progress is set into __do_call_rcu_ttrace(). The next patch will call it from __free_rcu(). No functional change. Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/20260930095920.601738-2-alexei.starovoitov@gmail.com Signed-off-by: Kumar Kartikeya Dwivedi --- kernel/bpf/memalloc.c | 27 +++++++++++++++++---------- 1 file changed, 17 insertions(+), 10 deletions(-) (limited to 'kernel') diff --git a/kernel/bpf/memalloc.c b/kernel/bpf/memalloc.c index 8a8f088e83e6..08e4dde66cd5 100644 --- a/kernel/bpf/memalloc.c +++ b/kernel/bpf/memalloc.c @@ -298,19 +298,10 @@ static void enque_to_free(struct bpf_mem_cache *c, void *obj) llist_add(llnode, &c->free_by_rcu_ttrace); } -static void do_call_rcu_ttrace(struct bpf_mem_cache *c) +static void __do_call_rcu_ttrace(struct bpf_mem_cache *c) { struct llist_node *llnode, *t; - if (atomic_xchg(&c->call_rcu_ttrace_in_progress, 1)) { - if (unlikely(READ_ONCE(c->draining))) { - scoped_guard(raw_spinlock_irqsave, &c->lock) - llnode = llist_del_all(&c->free_by_rcu_ttrace); - free_all(c, llnode, !!c->percpu_size); - } - return; - } - WARN_ON_ONCE(!llist_empty(&c->waiting_for_gp_ttrace)); llist_for_each_safe(llnode, t, llist_del_all(&c->free_by_rcu_ttrace)) llist_add(llnode, &c->waiting_for_gp_ttrace); @@ -328,6 +319,22 @@ static void do_call_rcu_ttrace(struct bpf_mem_cache *c) call_rcu_tasks_trace(&c->rcu_ttrace, __free_rcu); } +static void do_call_rcu_ttrace(struct bpf_mem_cache *c) +{ + struct llist_node *llnode; + + if (atomic_xchg(&c->call_rcu_ttrace_in_progress, 1)) { + if (unlikely(READ_ONCE(c->draining))) { + scoped_guard(raw_spinlock_irqsave, &c->lock) + llnode = llist_del_all(&c->free_by_rcu_ttrace); + free_all(c, llnode, !!c->percpu_size); + } + return; + } + + __do_call_rcu_ttrace(c); +} + static void free_bulk(struct bpf_mem_cache *c) { struct bpf_mem_cache *tgt = c->tgt; -- cgit v1.2.3 From fbd97dd1d3ce32d32fb7be86acc3fdb7c04fa043 Mon Sep 17 00:00:00 2001 From: Alexei Starovoitov Date: Wed, 30 Sep 2026 09:59:19 +0000 Subject: bpf: Fix objects stuck in free_by_rcu_ttrace do_call_rcu_ttrace() returns early when call_rcu_ttrace_in_progress is set and leaves the objects in free_by_rcu_ttrace. __free_rcu() frees waiting_for_gp_ttrace only and clears the flag. Hence the objects that free_bulk() or __free_by_rcu() added while RCU tasks trace GP was in flight stay in free_by_rcu_ttrace until free_bulk() or alloc_bulk() is called for the same bpf_mem_cache again, which may never happen. The number of such objects is not bounded. Turn call_rcu_ttrace_in_progress into three states: 0 - idle 1 - __free_rcu() is queued 2 - __free_rcu() is queued and free_by_rcu_ttrace got more objects since do_call_rcu_ttrace() sets 2. __free_rcu() does cmpxchg(1 -> 0) and starts the next GP when it fails. It cannot clear the flag first and check free_by_rcu_ttrace later, since bpf_mem_alloc_destroy() frees bpf_mem_cache without waiting for RCU callbacks when the flag is zero. Now __free_rcu() queues itself, so the one that didn't see 'draining' may do call_rcu_tasks_trace() after rcu_barrier_tasks_trace() in free_mem_alloc(). Queue it under rcu_read_lock() and do synchronize_rcu() before the barriers. Calling rcu_barrier_tasks_trace() twice works too, but creating and destroying hash maps in a loop on many cpus slows down to one free_mem_alloc() per GP and kworkers pile up. Fixes: 8d5a8011b35d ("bpf: Batch call_rcu callbacks instead of SLAB_TYPESAFE_BY_RCU.") Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/20260930095920.601738-3-alexei.starovoitov@gmail.com Signed-off-by: Kumar Kartikeya Dwivedi --- kernel/bpf/memalloc.c | 34 ++++++++++++++++++++++++++++++++-- 1 file changed, 32 insertions(+), 2 deletions(-) (limited to 'kernel') diff --git a/kernel/bpf/memalloc.c b/kernel/bpf/memalloc.c index 08e4dde66cd5..15684d0fc883 100644 --- a/kernel/bpf/memalloc.c +++ b/kernel/bpf/memalloc.c @@ -118,6 +118,11 @@ struct bpf_mem_cache { struct llist_head free_by_rcu_ttrace; struct llist_head waiting_for_gp_ttrace; struct rcu_head rcu_ttrace; + /* + * 0 - idle + * 1 - __free_rcu() is queued + * 2 - __free_rcu() is queued and free_by_rcu_ttrace got more objects since + */ atomic_t call_rcu_ttrace_in_progress; raw_spinlock_t lock; }; @@ -276,6 +281,8 @@ static int free_all(struct bpf_mem_cache *c, struct llist_node *llnode, bool per return cnt; } +static void __do_call_rcu_ttrace(struct bpf_mem_cache *c); + static void __free_rcu(struct rcu_head *head) { struct bpf_mem_cache *c = container_of(head, struct bpf_mem_cache, rcu_ttrace); @@ -285,7 +292,19 @@ static void __free_rcu(struct rcu_head *head) llnode = llist_del_all(&c->waiting_for_gp_ttrace); free_all(c, llnode, !!c->percpu_size); - atomic_set(&c->call_rcu_ttrace_in_progress, 0); + + /* + * do_call_rcu_ttrace() that ran while GP was in flight left its objects + * in free_by_rcu_ttrace. This cache may never free or alloc in bulk + * again, so start the next GP from here. + * 'c' can be freed as soon as call_rcu_ttrace_in_progress is zero. + */ + if (atomic_cmpxchg(&c->call_rcu_ttrace_in_progress, 1, 0) == 1) + return; + + /* Pairs with synchronize_rcu() in free_mem_alloc() */ + guard(rcu)(); + __do_call_rcu_ttrace(c); } static void enque_to_free(struct bpf_mem_cache *c, void *obj) @@ -302,6 +321,12 @@ static void __do_call_rcu_ttrace(struct bpf_mem_cache *c) { struct llist_node *llnode, *t; + /* + * Must be done before llist_del_all(). Objects that it misses were + * added by do_call_rcu_ttrace() that will set 2 after this store. + */ + atomic_set(&c->call_rcu_ttrace_in_progress, 1); + WARN_ON_ONCE(!llist_empty(&c->waiting_for_gp_ttrace)); llist_for_each_safe(llnode, t, llist_del_all(&c->free_by_rcu_ttrace)) llist_add(llnode, &c->waiting_for_gp_ttrace); @@ -323,7 +348,7 @@ static void do_call_rcu_ttrace(struct bpf_mem_cache *c) { struct llist_node *llnode; - if (atomic_xchg(&c->call_rcu_ttrace_in_progress, 1)) { + if (atomic_xchg(&c->call_rcu_ttrace_in_progress, 2)) { if (unlikely(READ_ONCE(c->draining))) { scoped_guard(raw_spinlock_irqsave, &c->lock) llnode = llist_del_all(&c->free_by_rcu_ttrace); @@ -707,7 +732,12 @@ static void free_mem_alloc(struct bpf_mem_alloc *ma) * to wait for the pending __free_by_rcu(), and __free_rcu(). RCU Tasks * Trace grace period implies RCU grace period, so all __free_rcu don't * need extra call_rcu() (and thus extra rcu_barrier() here). + * + * __free_rcu() queues itself again unless it sees 'draining'. After + * synchronize_rcu() it either did that already or will not do it, so + * rcu_barrier_tasks_trace() cannot miss it. */ + synchronize_rcu(); rcu_barrier(); /* wait for __free_by_rcu */ rcu_barrier_tasks_trace(); /* wait for __free_rcu */ free_mem_alloc_no_barrier(ma); -- cgit v1.2.3 From 7a39c732a22ec4a369af9e19fbe3d666ec83eec4 Mon Sep 17 00:00:00 2001 From: Leon Hwang Date: Wed, 30 Sep 2026 13:36:18 +0800 Subject: kprobes: Skip disarmed probes when checking optkprobe overlap On x86, an optkprobe at A replaces five bytes with a jump. If a disabled probe B is at A+2, get_optimized_kprobe() stops at B when arming a new probe C at A+4. It leaves A optimized: A A+1 A+2 A+3 A+4 A's jump | e9 | d0 | d1 | d2 | d3 | after C | e9 | d0 | d1 | d2 | cc | The INT3 for C overwrites the last byte of A's jump displacement, so execution can jump to the wrong address. B can have prepared optinsns while disarmed, but has no jump to unoptimize. Continue past disarmed and unprepared probes to find the active optimized probe before arming a probe in its jump. Link: https://lore.kernel.org/all/20260930053618.104498-1-leon.hwang@linux.dev/ Fixes: afd66255b9a4 ("kprobes: Introduce kprobes jump optimization") Cc: stable@vger.kernel.org Signed-off-by: Leon Hwang Signed-off-by: Masami Hiramatsu (Google) --- kernel/kprobes.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) (limited to 'kernel') diff --git a/kernel/kprobes.c b/kernel/kprobes.c index 4edd8ca5c657..e787e4948c8b 100644 --- a/kernel/kprobes.c +++ b/kernel/kprobes.c @@ -496,14 +496,16 @@ static bool kprobe_queued(struct kprobe *p) static struct kprobe *get_optimized_kprobe(kprobe_opcode_t *addr) { int i; - struct kprobe *p = NULL; + struct kprobe *p; struct optimized_kprobe *op; /* Don't check i == 0, since that is a breakpoint case. */ - for (i = 1; !p && i < MAX_OPTIMIZED_LENGTH / sizeof(kprobe_opcode_t); i++) + for (i = 1; i < MAX_OPTIMIZED_LENGTH / sizeof(kprobe_opcode_t); i++) { p = get_kprobe(addr - i); + /* A disabled probe can have prepared, but inactive, optinsns. */ + if (!p || !kprobe_optready(p) || kprobe_disarmed(p)) + continue; - if (p && kprobe_optready(p)) { op = container_of(p, struct optimized_kprobe, kp); if (arch_within_optimized_kprobe(op, addr)) return p; -- cgit v1.2.3 From 26f6b6357b1b06e6aaa9b8d796989cca785d8e1d Mon Sep 17 00:00:00 2001 From: Kuan-Wei Chiu Date: Thu, 1 Oct 2026 10:25:15 +0200 Subject: irq: Make refcount_interrupt kunit test selectable Currently, refcount_interrupt_test is built unconditionally when CONFIG_KUNIT is enabled, causing it to run unexpectedly during boot. Fix this by introducing CONFIG_REFCOUNT_INTERRUPT_KUNIT_TEST so the test can be configured independently, following standard kunit practices. Fixes: 07a88e2bcd5b ("irq: Add KUnit test for refcounted interrupt enable/disable") Signed-off-by: Kuan-Wei Chiu Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Lyude Paul Reviewed-by: Radu Rendec Reviewed-by: Boqun Feng Link: https://patch.msgid.link/20261001082519.16195-2-boqun@kernel.org --- kernel/irq/Kconfig | 12 ++++++++++++ kernel/irq/Makefile | 2 +- 2 files changed, 13 insertions(+), 1 deletion(-) (limited to 'kernel') diff --git a/kernel/irq/Kconfig b/kernel/irq/Kconfig index 05cba4e16dad..6923f37eaab4 100644 --- a/kernel/irq/Kconfig +++ b/kernel/irq/Kconfig @@ -150,6 +150,18 @@ config IRQ_KUNIT_TEST If unsure, say N. +config REFCOUNT_INTERRUPT_KUNIT_TEST + tristate "Test refcounted interrupt enable/disable" if !KUNIT_ALL_TESTS + depends on KUNIT + default KUNIT_ALL_TESTS + help + This builds the kunit tests for the refcounted interrupt + infrastructure. It verifies the correctness of single, nested, + and multiple interrupt enable/disable state changes and ensures + that the underlying reference counting mechanisms work as expected. + + If unsure, say N. + endmenu config GENERIC_IRQ_MULTI_HANDLER diff --git a/kernel/irq/Makefile b/kernel/irq/Makefile index 44c4d6fc502a..0e5df962a149 100644 --- a/kernel/irq/Makefile +++ b/kernel/irq/Makefile @@ -16,4 +16,4 @@ obj-$(CONFIG_SMP) += affinity.o obj-$(CONFIG_GENERIC_IRQ_DEBUGFS) += debugfs.o obj-$(CONFIG_GENERIC_IRQ_MATRIX_ALLOCATOR) += matrix.o obj-$(CONFIG_IRQ_KUNIT_TEST) += irq_test.o -obj-$(CONFIG_KUNIT) += refcount_interrupt_test.o +obj-$(CONFIG_REFCOUNT_INTERRUPT_KUNIT_TEST) += refcount_interrupt_test.o -- cgit v1.2.3 From f35e3b5784221654f9cdbd6222275a7fa203f6c3 Mon Sep 17 00:00:00 2001 From: Chris Mason Date: Thu, 1 Oct 2026 13:50:22 +0000 Subject: futex: Fix private hash use-after-free on resize poll_state_synchronize_rcu(mm->futex.phash.batches) is used by futex_ref_drop() to check that a grace period has passed since the current hash was published. This relies on batches referencing a grace period which started after the hash pointer was assigned. __futex_pivot_hash() sets mmph->batches before it replaces mmph->hash: scoped_guard(rcu) { mmph->batches = get_state_synchronize_rcu(); rcu_assign_pointer(mmph->hash, new); } The scoped_guard(rcu) doesn't stop new grace periods from starting, and if one starts between those two assignments, futex_ref_drop() can move forward while a reader still holds a pointer to the old hash. Fix things by setting mmph->batches after assigning mmph->hash. The scoped_guard(rcu) isn't needed, so let's drop that as well. Fixes: 56180dd20c19 ("futex: Use RCU-based per-CPU reference counting instead of rcuref_t") Assisted-by: kres Signed-off-by: Chris Mason Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Paul E. McKenney Link: https://patch.msgid.link/20261001135022.2220288-1-mason@kernel.org --- kernel/futex/core.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) (limited to 'kernel') diff --git a/kernel/futex/core.c b/kernel/futex/core.c index a061f54b606d..095f9fe440e3 100644 --- a/kernel/futex/core.c +++ b/kernel/futex/core.c @@ -213,10 +213,12 @@ static bool __futex_pivot_hash(struct mm_struct *mm, struct futex_private_hash * futex_rehash_private(fph, new); } new->state = FR_PERCPU; - scoped_guard(rcu) { - mmph->batches = get_state_synchronize_rcu(); - rcu_assign_pointer(mmph->hash, new); - } + rcu_assign_pointer(mmph->hash, new); + /* + * mmph->batches must reference a grace period which started after + * mmph->hash was assigned. See futex_ref_drop(). + */ + mmph->batches = get_state_synchronize_rcu(); kvfree_rcu(fph, rcu); return true; } -- cgit v1.2.3 From de020dc8049bfb2b22e3b6d99c031feb2e22d112 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?=C3=96mer=20Mete=20Kaya?= Date: Tue, 29 Sep 2026 11:10:34 +0300 Subject: bpf: Fix missing migration protection in __rhtab_map_lookup_and_delete_batch() MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit bpf_mem_cache_free_rcu() uses this_cpu_ptr() which requires migration to be disabled. All callers of rhtab_delete_elem() disable migration except __rhtab_map_lookup_and_delete_batch(), which calls it under rcu_read_lock() only. On CONFIG_PREEMPT_RCU, rcu_read_lock() does not disable preemption or migration, so the task can migrate between CPUs during the delete loop, causing this_cpu_ptr() to trigger: BUG: using smp_processor_id() in preemptible [00000000] code Fix by wrapping the delete loop in migrate_disable()/migrate_enable() in __rhtab_map_lookup_and_delete_batch(), matching the migration protection that the other callers already provide. Fixes: 818e00848227 ("bpf: Implement iteration ops for resizable hashtab") Reported-by: syzbot+fd7e415d891073b83e1f@syzkaller.appspotmail.com Signed-off-by: Ömer Mete Kaya Signed-off-by: Alexei Starovoitov Acked-by: Mykyta Yatsenko Link: https://patch.msgid.link/20260929081609.557899-1-omermetekaya0@gmail.com Closes: https://syzkaller.appspot.com/bug?extid=fd7e415d891073b83e1f --- kernel/bpf/hashtab.c | 2 ++ 1 file changed, 2 insertions(+) (limited to 'kernel') diff --git a/kernel/bpf/hashtab.c b/kernel/bpf/hashtab.c index 548eb1cc7c45..13a2356c84cf 100644 --- a/kernel/bpf/hashtab.c +++ b/kernel/bpf/hashtab.c @@ -3374,8 +3374,10 @@ static int __rhtab_map_lookup_and_delete_batch(struct bpf_map *map, } if (do_delete) { + migrate_disable(); for (i = 0; i < total; i++) rhtab_delete_elem(rhtab, del_elems[i], NULL, 0); + migrate_enable(); } rcu_read_unlock(); -- cgit v1.2.3