From dc8aea47b928cc153b591b3558829ce42f685074 Mon Sep 17 00:00:00 2001 From: Carlos Llamas Date: Thu, 26 Sep 2024 23:36:12 +0000 Subject: binder: fix node UAF in binder_add_freeze_work() In binder_add_freeze_work() we iterate over the proc->nodes with the proc->inner_lock held. However, this lock is temporarily dropped in order to acquire the node->lock first (lock nesting order). This can race with binder_node_release() and trigger a use-after-free: ================================================================== BUG: KASAN: slab-use-after-free in _raw_spin_lock+0xe4/0x19c Write of size 4 at addr ffff53c04c29dd04 by task freeze/640 CPU: 5 UID: 0 PID: 640 Comm: freeze Not tainted 6.11.0-07343-ga727812a8d45 #17 Hardware name: linux,dummy-virt (DT) Call trace: _raw_spin_lock+0xe4/0x19c binder_add_freeze_work+0x148/0x478 binder_ioctl+0x1e70/0x25ac __arm64_sys_ioctl+0x124/0x190 Allocated by task 637: __kmalloc_cache_noprof+0x12c/0x27c binder_new_node+0x50/0x700 binder_transaction+0x35ac/0x6f74 binder_thread_write+0xfb8/0x42a0 binder_ioctl+0x18f0/0x25ac __arm64_sys_ioctl+0x124/0x190 Freed by task 637: kfree+0xf0/0x330 binder_thread_read+0x1e88/0x3a68 binder_ioctl+0x16d8/0x25ac __arm64_sys_ioctl+0x124/0x190 ================================================================== Fix the race by taking a temporary reference on the node before releasing the proc->inner lock. This ensures the node remains alive while in use. Fixes: d579b04a52a1 ("binder: frozen notification") Cc: stable@vger.kernel.org Reviewed-by: Alice Ryhl Acked-by: Todd Kjos Signed-off-by: Carlos Llamas Link: https://lore.kernel.org/r/20240926233632.821189-2-cmllamas@google.com Signed-off-by: Greg Kroah-Hartman --- drivers/android/binder.c | 7 +++++++ 1 file changed, 7 insertions(+) (limited to 'drivers/android') diff --git a/drivers/android/binder.c b/drivers/android/binder.c index 978740537a1a..4d90203ea048 100644 --- a/drivers/android/binder.c +++ b/drivers/android/binder.c @@ -5552,6 +5552,7 @@ static bool binder_txns_pending_ilocked(struct binder_proc *proc) static void binder_add_freeze_work(struct binder_proc *proc, bool is_frozen) { + struct binder_node *prev = NULL; struct rb_node *n; struct binder_ref *ref; @@ -5560,7 +5561,10 @@ static void binder_add_freeze_work(struct binder_proc *proc, bool is_frozen) struct binder_node *node; node = rb_entry(n, struct binder_node, rb_node); + binder_inc_node_tmpref_ilocked(node); binder_inner_proc_unlock(proc); + if (prev) + binder_put_node(prev); binder_node_lock(node); hlist_for_each_entry(ref, &node->refs, node_entry) { /* @@ -5586,10 +5590,13 @@ static void binder_add_freeze_work(struct binder_proc *proc, bool is_frozen) } binder_inner_proc_unlock(ref->proc); } + prev = node; binder_node_unlock(node); binder_inner_proc_lock(proc); } binder_inner_proc_unlock(proc); + if (prev) + binder_put_node(prev); } static int binder_ioctl_freeze(struct binder_freeze_info *info, -- cgit v1.2.3 From 011e69a1b23011c0db3af4b8293fdd4522cc97b0 Mon Sep 17 00:00:00 2001 From: Carlos Llamas Date: Thu, 26 Sep 2024 23:36:13 +0000 Subject: binder: fix OOB in binder_add_freeze_work() In binder_add_freeze_work() we iterate over the proc->nodes with the proc->inner_lock held. However, this lock is temporarily dropped to acquire the node->lock first (lock nesting order). This can race with binder_deferred_release() which removes the nodes from the proc->nodes rbtree and adds them into binder_dead_nodes list. This leads to a broken iteration in binder_add_freeze_work() as rb_next() will use data from binder_dead_nodes, triggering an out-of-bounds access: ================================================================== BUG: KASAN: global-out-of-bounds in rb_next+0xfc/0x124 Read of size 8 at addr ffffcb84285f7170 by task freeze/660 CPU: 8 UID: 0 PID: 660 Comm: freeze Not tainted 6.11.0-07343-ga727812a8d45 #18 Hardware name: linux,dummy-virt (DT) Call trace: rb_next+0xfc/0x124 binder_add_freeze_work+0x344/0x534 binder_ioctl+0x1e70/0x25ac __arm64_sys_ioctl+0x124/0x190 The buggy address belongs to the variable: binder_dead_nodes+0x10/0x40 [...] ================================================================== This is possible because proc->nodes (rbtree) and binder_dead_nodes (list) share entries in binder_node through a union: struct binder_node { [...] union { struct rb_node rb_node; struct hlist_node dead_node; }; Fix the race by checking that the proc is still alive. If not, simply break out of the iteration. Fixes: d579b04a52a1 ("binder: frozen notification") Cc: stable@vger.kernel.org Reviewed-by: Alice Ryhl Acked-by: Todd Kjos Signed-off-by: Carlos Llamas Link: https://lore.kernel.org/r/20240926233632.821189-3-cmllamas@google.com Signed-off-by: Greg Kroah-Hartman --- drivers/android/binder.c | 2 ++ 1 file changed, 2 insertions(+) (limited to 'drivers/android') diff --git a/drivers/android/binder.c b/drivers/android/binder.c index 4d90203ea048..8bca2de6fa24 100644 --- a/drivers/android/binder.c +++ b/drivers/android/binder.c @@ -5593,6 +5593,8 @@ static void binder_add_freeze_work(struct binder_proc *proc, bool is_frozen) prev = node; binder_node_unlock(node); binder_inner_proc_lock(proc); + if (proc->is_dead) + break; } binder_inner_proc_unlock(proc); if (prev) -- cgit v1.2.3 From 7e20434cbca814cb91a0a261ca0106815ef48e5f Mon Sep 17 00:00:00 2001 From: Carlos Llamas Date: Thu, 26 Sep 2024 23:36:14 +0000 Subject: binder: fix freeze UAF in binder_release_work() When a binder reference is cleaned up, any freeze work queued in the associated process should also be removed. Otherwise, the reference is freed while its ref->freeze.work is still queued in proc->work leading to a use-after-free issue as shown by the following KASAN report: ================================================================== BUG: KASAN: slab-use-after-free in binder_release_work+0x398/0x3d0 Read of size 8 at addr ffff31600ee91488 by task kworker/5:1/211 CPU: 5 UID: 0 PID: 211 Comm: kworker/5:1 Not tainted 6.11.0-rc7-00382-gfc6c92196396 #22 Hardware name: linux,dummy-virt (DT) Workqueue: events binder_deferred_func Call trace: binder_release_work+0x398/0x3d0 binder_deferred_func+0xb60/0x109c process_one_work+0x51c/0xbd4 worker_thread+0x608/0xee8 Allocated by task 703: __kmalloc_cache_noprof+0x130/0x280 binder_thread_write+0xdb4/0x42a0 binder_ioctl+0x18f0/0x25ac __arm64_sys_ioctl+0x124/0x190 invoke_syscall+0x6c/0x254 Freed by task 211: kfree+0xc4/0x230 binder_deferred_func+0xae8/0x109c process_one_work+0x51c/0xbd4 worker_thread+0x608/0xee8 ================================================================== This commit fixes the issue by ensuring any queued freeze work is removed when cleaning up a binder reference. Fixes: d579b04a52a1 ("binder: frozen notification") Cc: stable@vger.kernel.org Acked-by: Todd Kjos Reviewed-by: Alice Ryhl Signed-off-by: Carlos Llamas Link: https://lore.kernel.org/r/20240926233632.821189-4-cmllamas@google.com Signed-off-by: Greg Kroah-Hartman --- drivers/android/binder.c | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'drivers/android') diff --git a/drivers/android/binder.c b/drivers/android/binder.c index 8bca2de6fa24..d955135ee37a 100644 --- a/drivers/android/binder.c +++ b/drivers/android/binder.c @@ -1225,6 +1225,12 @@ static void binder_cleanup_ref_olocked(struct binder_ref *ref) binder_dequeue_work(ref->proc, &ref->death->work); binder_stats_deleted(BINDER_STAT_DEATH); } + + if (ref->freeze) { + binder_dequeue_work(ref->proc, &ref->freeze->work); + binder_stats_deleted(BINDER_STAT_FREEZE); + } + binder_stats_deleted(BINDER_STAT_REF); } -- cgit v1.2.3 From 830d7db744b42c693bf1db7e94db86d7efd91f0e Mon Sep 17 00:00:00 2001 From: Carlos Llamas Date: Thu, 26 Sep 2024 23:36:15 +0000 Subject: binder: fix BINDER_WORK_FROZEN_BINDER debug logs The BINDER_WORK_FROZEN_BINDER type is not handled in the binder_logs entries and it shows up as "unknown work" when logged: proc 649 context binder-test thread 649: l 00 need_return 0 tr 0 ref 13: desc 1 node 8 s 1 w 0 d 0000000053c4c0c3 unknown work: type 10 This patch add the freeze work type and is now logged as such: proc 637 context binder-test thread 637: l 00 need_return 0 tr 0 ref 8: desc 1 node 3 s 1 w 0 d 00000000dc39e9c6 has frozen binder Fixes: d579b04a52a1 ("binder: frozen notification") Cc: stable@vger.kernel.org Acked-by: Todd Kjos Signed-off-by: Carlos Llamas Reviewed-by: Alice Ryhl Link: https://lore.kernel.org/r/20240926233632.821189-5-cmllamas@google.com Signed-off-by: Greg Kroah-Hartman --- drivers/android/binder.c | 3 +++ 1 file changed, 3 insertions(+) (limited to 'drivers/android') diff --git a/drivers/android/binder.c b/drivers/android/binder.c index d955135ee37a..2be9f3559ed7 100644 --- a/drivers/android/binder.c +++ b/drivers/android/binder.c @@ -6408,6 +6408,9 @@ static void print_binder_work_ilocked(struct seq_file *m, case BINDER_WORK_CLEAR_DEATH_NOTIFICATION: seq_printf(m, "%shas cleared death notification\n", prefix); break; + case BINDER_WORK_FROZEN_BINDER: + seq_printf(m, "%shas frozen binder\n", prefix); + break; default: seq_printf(m, "%sunknown work: type %d\n", prefix, w->type); break; -- cgit v1.2.3 From 595ea72efff9fa65bc52b6406e0822f90841f266 Mon Sep 17 00:00:00 2001 From: Carlos Llamas Date: Thu, 26 Sep 2024 23:36:16 +0000 Subject: binder: fix BINDER_WORK_CLEAR_FREEZE_NOTIFICATION debug logs proc 699 context binder-test thread 699: l 00 need_return 0 tr 0 ref 25: desc 1 node 20 s 1 w 0 d 00000000c03e09a3 unknown work: type 11 proc 640 context binder-test thread 640: l 00 need_return 0 tr 0 ref 8: desc 1 node 3 s 1 w 0 d 000000002bb493e1 has cleared freeze notification Fixes: d579b04a52a1 ("binder: frozen notification") Cc: stable@vger.kernel.org Suggested-by: Alice Ryhl Signed-off-by: Carlos Llamas Reviewed-by: Alice Ryhl Acked-by: Todd Kjos Link: https://lore.kernel.org/r/20240926233632.821189-6-cmllamas@google.com Signed-off-by: Greg Kroah-Hartman --- drivers/android/binder.c | 3 +++ 1 file changed, 3 insertions(+) (limited to 'drivers/android') diff --git a/drivers/android/binder.c b/drivers/android/binder.c index 2be9f3559ed7..73dc6cbc1681 100644 --- a/drivers/android/binder.c +++ b/drivers/android/binder.c @@ -6411,6 +6411,9 @@ static void print_binder_work_ilocked(struct seq_file *m, case BINDER_WORK_FROZEN_BINDER: seq_printf(m, "%shas frozen binder\n", prefix); break; + case BINDER_WORK_CLEAR_FREEZE_NOTIFICATION: + seq_printf(m, "%shas cleared freeze notification\n", prefix); + break; default: seq_printf(m, "%sunknown work: type %d\n", prefix, w->type); break; -- cgit v1.2.3 From ca63c66935b978441055e3d87d30225267f99329 Mon Sep 17 00:00:00 2001 From: Carlos Llamas Date: Thu, 26 Sep 2024 23:36:17 +0000 Subject: binder: allow freeze notification for dead nodes Alice points out that binder_request_freeze_notification() should not return EINVAL when the relevant node is dead [1]. The node can die at any point even if the user input is valid. Instead, allow the request to be allocated but skip the initial notification for dead nodes. This avoids propagating unnecessary errors back to userspace. Fixes: d579b04a52a1 ("binder: frozen notification") Cc: stable@vger.kernel.org Suggested-by: Alice Ryhl Link: https://lore.kernel.org/all/CAH5fLghapZJ4PbbkC8V5A6Zay-_sgTzwVpwqk6RWWUNKKyJC_Q@mail.gmail.com/ [1] Signed-off-by: Carlos Llamas Acked-by: Todd Kjos Link: https://lore.kernel.org/r/20240926233632.821189-7-cmllamas@google.com Signed-off-by: Greg Kroah-Hartman --- drivers/android/binder.c | 28 +++++++++++++--------------- 1 file changed, 13 insertions(+), 15 deletions(-) (limited to 'drivers/android') diff --git a/drivers/android/binder.c b/drivers/android/binder.c index 73dc6cbc1681..415fc9759249 100644 --- a/drivers/android/binder.c +++ b/drivers/android/binder.c @@ -3856,7 +3856,6 @@ binder_request_freeze_notification(struct binder_proc *proc, { struct binder_ref_freeze *freeze; struct binder_ref *ref; - bool is_frozen; freeze = kzalloc(sizeof(*freeze), GFP_KERNEL); if (!freeze) @@ -3872,32 +3871,31 @@ binder_request_freeze_notification(struct binder_proc *proc, } binder_node_lock(ref->node); - - if (ref->freeze || !ref->node->proc) { - binder_user_error("%d:%d invalid BC_REQUEST_FREEZE_NOTIFICATION %s\n", - proc->pid, thread->pid, - ref->freeze ? "already set" : "dead node"); + if (ref->freeze) { + binder_user_error("%d:%d BC_REQUEST_FREEZE_NOTIFICATION already set\n", + proc->pid, thread->pid); binder_node_unlock(ref->node); binder_proc_unlock(proc); kfree(freeze); return -EINVAL; } - binder_inner_proc_lock(ref->node->proc); - is_frozen = ref->node->proc->is_frozen; - binder_inner_proc_unlock(ref->node->proc); binder_stats_created(BINDER_STAT_FREEZE); INIT_LIST_HEAD(&freeze->work.entry); freeze->cookie = handle_cookie->cookie; freeze->work.type = BINDER_WORK_FROZEN_BINDER; - freeze->is_frozen = is_frozen; - ref->freeze = freeze; - binder_inner_proc_lock(proc); - binder_enqueue_work_ilocked(&ref->freeze->work, &proc->todo); - binder_wakeup_proc_ilocked(proc); - binder_inner_proc_unlock(proc); + if (ref->node->proc) { + binder_inner_proc_lock(ref->node->proc); + freeze->is_frozen = ref->node->proc->is_frozen; + binder_inner_proc_unlock(ref->node->proc); + + binder_inner_proc_lock(proc); + binder_enqueue_work_ilocked(&freeze->work, &proc->todo); + binder_wakeup_proc_ilocked(proc); + binder_inner_proc_unlock(proc); + } binder_node_unlock(ref->node); binder_proc_unlock(proc); -- cgit v1.2.3 From 1db76ec2b4b206ff943e292a0b55e68ff3443598 Mon Sep 17 00:00:00 2001 From: Carlos Llamas Date: Thu, 26 Sep 2024 23:36:18 +0000 Subject: binder: fix memleak of proc->delivered_freeze If a freeze notification is cleared with BC_CLEAR_FREEZE_NOTIFICATION before calling binder_freeze_notification_done(), then it is detached from its reference (e.g. ref->freeze) but the work remains queued in proc->delivered_freeze. This leads to a memory leak when the process exits as any pending entries in proc->delivered_freeze are not freed: unreferenced object 0xffff38e8cfa36180 (size 64): comm "binder-util", pid 655, jiffies 4294936641 hex dump (first 32 bytes): b8 e9 9e c8 e8 38 ff ff b8 e9 9e c8 e8 38 ff ff .....8.......8.. 0b 00 00 00 00 00 00 00 3c 1f 4b 00 00 00 00 00 ........<.K..... backtrace (crc 95983b32): [<000000000d0582cf>] kmemleak_alloc+0x34/0x40 [<000000009c99a513>] __kmalloc_cache_noprof+0x208/0x280 [<00000000313b1704>] binder_thread_write+0xdec/0x439c [<000000000cbd33bb>] binder_ioctl+0x1b68/0x22cc [<000000002bbedeeb>] __arm64_sys_ioctl+0x124/0x190 [<00000000b439adee>] invoke_syscall+0x6c/0x254 [<00000000173558fc>] el0_svc_common.constprop.0+0xac/0x230 [<0000000084f72311>] do_el0_svc+0x40/0x58 [<000000008b872457>] el0_svc+0x38/0x78 [<00000000ee778653>] el0t_64_sync_handler+0x120/0x12c [<00000000a8ec61bf>] el0t_64_sync+0x190/0x194 This patch fixes the leak by ensuring that any pending entries in proc->delivered_freeze are freed during binder_deferred_release(). Fixes: d579b04a52a1 ("binder: frozen notification") Cc: stable@vger.kernel.org Signed-off-by: Carlos Llamas Reviewed-by: Alice Ryhl Acked-by: Todd Kjos Link: https://lore.kernel.org/r/20240926233632.821189-8-cmllamas@google.com Signed-off-by: Greg Kroah-Hartman --- drivers/android/binder.c | 11 +++++++++++ 1 file changed, 11 insertions(+) (limited to 'drivers/android') diff --git a/drivers/android/binder.c b/drivers/android/binder.c index 415fc9759249..7c09b5e38e32 100644 --- a/drivers/android/binder.c +++ b/drivers/android/binder.c @@ -5155,6 +5155,16 @@ static void binder_release_work(struct binder_proc *proc, } break; case BINDER_WORK_NODE: break; + case BINDER_WORK_CLEAR_FREEZE_NOTIFICATION: { + struct binder_ref_freeze *freeze; + + freeze = container_of(w, struct binder_ref_freeze, work); + binder_debug(BINDER_DEBUG_DEAD_TRANSACTION, + "undelivered freeze notification, %016llx\n", + (u64)freeze->cookie); + kfree(freeze); + binder_stats_deleted(BINDER_STAT_FREEZE); + } break; default: pr_err("unexpected work type, %d, not freed\n", wtype); @@ -6273,6 +6283,7 @@ static void binder_deferred_release(struct binder_proc *proc) binder_release_work(proc, &proc->todo); binder_release_work(proc, &proc->delivered_death); + binder_release_work(proc, &proc->delivered_freeze); binder_debug(BINDER_DEBUG_OPEN_CLOSE, "%s: %d threads %d, nodes %d (ref %d), refs %d, active transactions %d\n", -- cgit v1.2.3 From cb2aeb2ec25884133110ffe5a67ff3cf7dee5ceb Mon Sep 17 00:00:00 2001 From: Carlos Llamas Date: Thu, 26 Sep 2024 23:36:19 +0000 Subject: binder: add delivered_freeze to debugfs output Add the pending proc->delivered_freeze work to the debugfs output. This information was omitted in the original implementation of the freeze notification and can be valuable for debugging issues. Fixes: d579b04a52a1 ("binder: frozen notification") Cc: stable@vger.kernel.org Signed-off-by: Carlos Llamas Acked-by: Todd Kjos Reviewed-by: Alice Ryhl Link: https://lore.kernel.org/r/20240926233632.821189-9-cmllamas@google.com Signed-off-by: Greg Kroah-Hartman --- drivers/android/binder.c | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'drivers/android') diff --git a/drivers/android/binder.c b/drivers/android/binder.c index 7c09b5e38e32..ef353ca13c35 100644 --- a/drivers/android/binder.c +++ b/drivers/android/binder.c @@ -6569,6 +6569,10 @@ static void print_binder_proc(struct seq_file *m, seq_puts(m, " has delivered dead binder\n"); break; } + list_for_each_entry(w, &proc->delivered_freeze, entry) { + seq_puts(m, " has delivered freeze binder\n"); + break; + } binder_inner_proc_unlock(proc); if (!print_all && m->count == header_pos) m->count = start_pos; -- cgit v1.2.3