From a3125bc01884431d30d731461634c8295b6f0529 Mon Sep 17 00:00:00 2001 From: Yazhou Tang Date: Wed, 4 Mar 2026 16:32:27 +0800 Subject: bpf: Reset register ID for BPF_END value tracking When a register undergoes a BPF_END (byte swap) operation, its scalar value is mutated in-place. If this register previously shared a scalar ID with another register (e.g., after an `r1 = r0` assignment), this tie must be broken. Currently, the verifier misses resetting `dst_reg->id` to 0 for BPF_END. Consequently, if a conditional jump checks the swapped register, the verifier incorrectly propagates the learned bounds to the linked register, leading to false confidence in the linked register's value and potentially allowing out-of-bounds memory accesses. Fix this by explicitly resetting `dst_reg->id` to 0 in the BPF_END case to break the scalar tie, similar to how BPF_NEG handles it via `__mark_reg_known`. Fixes: 9d2119984224 ("bpf: Add bitwise tracking for BPF_END") Closes: https://lore.kernel.org/bpf/AMBPR06MB108683CFEB1CB8D9E02FC95ECF17EA@AMBPR06MB10868.eurprd06.prod.outlook.com/ Link: https://lore.kernel.org/bpf/4be25f7442a52244d0dd1abb47bc6750e57984c9.camel@gmail.com/ Reported-by: Guillaume Laporte Co-developed-by: Tianci Cao Signed-off-by: Tianci Cao Co-developed-by: Shenghao Yuan Signed-off-by: Shenghao Yuan Signed-off-by: Yazhou Tang Acked-by: Eduard Zingerman Link: https://lore.kernel.org/r/20260304083228.142016-2-tangyazhou@zju.edu.cn Signed-off-by: Alexei Starovoitov --- kernel/bpf/verifier.c | 7 +++++++ 1 file changed, 7 insertions(+) (limited to 'kernel/bpf') diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 159b25f8269d..df22bfc572e2 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -15910,6 +15910,13 @@ static void scalar_byte_swap(struct bpf_reg_state *dst_reg, struct bpf_insn *ins /* Apply bswap if alu64 or switch between big-endian and little-endian machines */ bool need_bswap = alu64 || (to_le == is_big_endian); + /* + * If the register is mutated, manually reset its scalar ID to break + * any existing ties and avoid incorrect bounds propagation. + */ + if (need_bswap || insn->imm == 16 || insn->imm == 32) + dst_reg->id = 0; + if (need_bswap) { if (insn->imm == 16) dst_reg->var_off = tnum_bswap16(dst_reg->var_off); -- cgit v1.2.3 From 2321a9596d2260310267622e0ad8fbfa6f95378f Mon Sep 17 00:00:00 2001 From: Sachin Kumar Date: Mon, 9 Mar 2026 18:25:42 +0000 Subject: bpf: Fix constant blinding for PROBE_MEM32 stores BPF_ST | BPF_PROBE_MEM32 immediate stores are not handled by bpf_jit_blind_insn(), allowing user-controlled 32-bit immediates to survive unblinded into JIT-compiled native code when bpf_jit_harden >= 1. The root cause is that convert_ctx_accesses() rewrites BPF_ST|BPF_MEM to BPF_ST|BPF_PROBE_MEM32 for arena pointer stores during verification, before bpf_jit_blind_constants() runs during JIT compilation. The blinding switch only matches BPF_ST|BPF_MEM (mode 0x60), not BPF_ST|BPF_PROBE_MEM32 (mode 0xa0). The instruction falls through unblinded. Add BPF_ST|BPF_PROBE_MEM32 cases to bpf_jit_blind_insn() alongside the existing BPF_ST|BPF_MEM cases. The blinding transformation is identical: load the blinded immediate into BPF_REG_AX via mov+xor, then convert the immediate store to a register store (BPF_STX). The rewritten STX instruction must preserve the BPF_PROBE_MEM32 mode so the architecture JIT emits the correct arena addressing (R12-based on x86-64). Cannot use the BPF_STX_MEM() macro here because it hardcodes BPF_MEM mode; construct the instruction directly instead. Fixes: 6082b6c328b5 ("bpf: Recognize addr_space_cast instruction in the verifier.") Reviewed-by: Puranjay Mohan Reviewed-by: Emil Tsalapatis Signed-off-by: Sachin Kumar Acked-by: Daniel Borkmann Link: https://lore.kernel.org/r/Y6IT5VvNRchPBLI5D7JZHBzZrU9rb0ycRJPJzJSXGj7kJlX8RJwZFSM2YZjcDxoQKABkxt1T8Os2gi23PYyFuQe6KkZGWVyfz8K5afdy9ak=@protonmail.com Signed-off-by: Alexei Starovoitov --- kernel/bpf/core.c | 21 +++++++++++++++++++++ 1 file changed, 21 insertions(+) (limited to 'kernel/bpf') diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c index 3ece2da55625..9e126be33755 100644 --- a/kernel/bpf/core.c +++ b/kernel/bpf/core.c @@ -1422,6 +1422,27 @@ static int bpf_jit_blind_insn(const struct bpf_insn *from, *to++ = BPF_ALU64_IMM(BPF_XOR, BPF_REG_AX, imm_rnd); *to++ = BPF_STX_MEM(from->code, from->dst_reg, BPF_REG_AX, from->off); break; + + case BPF_ST | BPF_PROBE_MEM32 | BPF_DW: + case BPF_ST | BPF_PROBE_MEM32 | BPF_W: + case BPF_ST | BPF_PROBE_MEM32 | BPF_H: + case BPF_ST | BPF_PROBE_MEM32 | BPF_B: + *to++ = BPF_ALU64_IMM(BPF_MOV, BPF_REG_AX, imm_rnd ^ + from->imm); + *to++ = BPF_ALU64_IMM(BPF_XOR, BPF_REG_AX, imm_rnd); + /* + * Cannot use BPF_STX_MEM() macro here as it + * hardcodes BPF_MEM mode, losing PROBE_MEM32 + * and breaking arena addressing in the JIT. + */ + *to++ = (struct bpf_insn) { + .code = BPF_STX | BPF_PROBE_MEM32 | + BPF_SIZE(from->code), + .dst_reg = from->dst_reg, + .src_reg = BPF_REG_AX, + .off = from->off, + }; + break; } out: return to - to_buff; -- cgit v1.2.3 From 146bd2a87a65aa407bb17fac70d8d583d19aba06 Mon Sep 17 00:00:00 2001 From: Kumar Kartikeya Dwivedi Date: Thu, 12 Mar 2026 13:53:07 -0700 Subject: bpf: Release module BTF IDR before module unload Gregory reported in [0] that the global_map_resize test when run in repeatedly ends up failing during program load. This stems from the fact that BTF reference has not dropped to zero after the previous run's module is unloaded, and the older module's BTF is still discoverable and visible. Later, in libbpf, load_module_btfs() will find the ID for this stale BTF, open its fd, and then it will be used during program load where later steps taking module reference using btf_try_get_module() fail since the underlying module for the BTF is gone. Logically, once a module is unloaded, it's associated BTF artifacts should become hidden. The BTF object inside the kernel may still remain alive as long its reference counts are alive, but it should no longer be discoverable. To fix this, let us call btf_free_id() from the MODULE_STATE_GOING case for the module unload to free the BTF associated IDR entry, and disable its discovery once module unload returns to user space. If a race happens during unload, the outcome is non-deterministic anyway. However, user space should be able to rely on the guarantee that once it has synchronously established a successful module unload, no more stale artifacts associated with this module can be obtained subsequently. Note that we must be careful to not invoke btf_free_id() in btf_put() when btf_is_module() is true now. There could be a window where the module unload drops a non-terminal reference, frees the IDR, but the same ID gets reused and the second unconditional btf_free_id() ends up releasing an unrelated entry. To avoid a special case for btf_is_module() case, set btf->id to zero to make btf_free_id() idempotent, such that we can unconditionally invoke it from btf_put(), and also from the MODULE_STATE_GOING case. Since zero is an invalid IDR, the idr_remove() should be a noop. Note that we can be sure that by the time we reach final btf_put() for btf_is_module() case, the btf_free_id() is already done, since the module itself holds the BTF reference, and it will call this function for the BTF before dropping its own reference. [0]: https://lore.kernel.org/bpf/cover.1773170190.git.grbell@redhat.com Fixes: 36e68442d1af ("bpf: Load and verify kernel module BTFs") Acked-by: Martin KaFai Lau Suggested-by: Martin KaFai Lau Reported-by: Gregory Bell Reviewed-by: Emil Tsalapatis Signed-off-by: Kumar Kartikeya Dwivedi Link: https://lore.kernel.org/r/20260312205307.1346991-1-memxor@gmail.com Signed-off-by: Alexei Starovoitov --- kernel/bpf/btf.c | 24 ++++++++++++++++++++---- 1 file changed, 20 insertions(+), 4 deletions(-) (limited to 'kernel/bpf') diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c index 4872d2a6c42d..71f9143fe90f 100644 --- a/kernel/bpf/btf.c +++ b/kernel/bpf/btf.c @@ -1787,7 +1787,16 @@ static void btf_free_id(struct btf *btf) * of the _bh() version. */ spin_lock_irqsave(&btf_idr_lock, flags); - idr_remove(&btf_idr, btf->id); + if (btf->id) { + idr_remove(&btf_idr, btf->id); + /* + * Clear the id here to make this function idempotent, since it will get + * called a couple of times for module BTFs: on module unload, and then + * the final btf_put(). btf_alloc_id() starts IDs with 1, so we can use + * 0 as sentinel value. + */ + WRITE_ONCE(btf->id, 0); + } spin_unlock_irqrestore(&btf_idr_lock, flags); } @@ -8115,7 +8124,7 @@ static void bpf_btf_show_fdinfo(struct seq_file *m, struct file *filp) { const struct btf *btf = filp->private_data; - seq_printf(m, "btf_id:\t%u\n", btf->id); + seq_printf(m, "btf_id:\t%u\n", READ_ONCE(btf->id)); } #endif @@ -8197,7 +8206,7 @@ int btf_get_info_by_fd(const struct btf *btf, if (copy_from_user(&info, uinfo, info_copy)) return -EFAULT; - info.id = btf->id; + info.id = READ_ONCE(btf->id); ubtf = u64_to_user_ptr(info.btf); btf_copy = min_t(u32, btf->data_size, info.btf_size); if (copy_to_user(ubtf, btf->data, btf_copy)) @@ -8260,7 +8269,7 @@ int btf_get_fd_by_id(u32 id) u32 btf_obj_id(const struct btf *btf) { - return btf->id; + return READ_ONCE(btf->id); } bool btf_is_kernel(const struct btf *btf) @@ -8382,6 +8391,13 @@ static int btf_module_notify(struct notifier_block *nb, unsigned long op, if (btf_mod->module != module) continue; + /* + * For modules, we do the freeing of BTF IDR as soon as + * module goes away to disable BTF discovery, since the + * btf_try_get_module() on such BTFs will fail. This may + * be called again on btf_put(), but it's ok to do so. + */ + btf_free_id(btf_mod->btf); list_del(&btf_mod->list); if (btf_mod->sysfs_attr) sysfs_remove_bin_file(btf_kobj, btf_mod->sysfs_attr); -- cgit v1.2.3 From 6c2128505f61b504c79a20b89596feba61388112 Mon Sep 17 00:00:00 2001 From: Ihor Solodrai Date: Thu, 19 Mar 2026 17:08:08 -0700 Subject: bpf: Fix exception exit lock checking for subprogs process_bpf_exit_full() passes check_lock = !curframe to check_resource_leak(), which is false in cases when bpf_throw() is called from a static subprog. This makes check_resource_leak() to skip validation of active_rcu_locks, active_preempt_locks, and active_irq_id on exception exits from subprogs. At runtime bpf_throw() unwinds the stack via ORC without releasing any user-acquired locks, which may cause various issues as the result. Fix by setting check_lock = true for exception exits regardless of curframe, since exceptions bypass all intermediate frame cleanup. Update the error message prefix to "bpf_throw" for exception exits to distinguish them from normal BPF_EXIT. Fix reject_subprog_with_rcu_read_lock test which was previously passing for the wrong reason. Test program returned directly from the subprog call without closing the RCU section, so the error was triggered by the unclosed RCU lock on normal exit, not by bpf_throw. Update __msg annotations for affected tests to match the new "bpf_throw" error prefix. The spin_lock case is not affected because they are already checked [1] at the call site in do_check_insn() before bpf_throw can run. [1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/kernel/bpf/verifier.c?h=v7.0-rc4#n21098 Assisted-by: Claude:claude-opus-4-6 Fixes: f18b03fabaa9 ("bpf: Implement BPF exceptions") Signed-off-by: Ihor Solodrai Acked-by: Yonghong Song Acked-by: Kumar Kartikeya Dwivedi Link: https://lore.kernel.org/r/20260320000809.643798-1-ihor.solodrai@linux.dev Signed-off-by: Alexei Starovoitov --- kernel/bpf/verifier.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'kernel/bpf') diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index df22bfc572e2..5c0e6809024f 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -20911,7 +20911,8 @@ static int process_bpf_exit_full(struct bpf_verifier_env *env, * state when it exits. */ int err = check_resource_leak(env, exception_exit, - !env->cur_state->curframe, + exception_exit || !env->cur_state->curframe, + exception_exit ? "bpf_throw" : "BPF_EXIT instruction in main prog"); if (err) return err; -- cgit v1.2.3 From c77b30bd1dcb61f66c640ff7d2757816210c7cb0 Mon Sep 17 00:00:00 2001 From: Jenny Guanni Qu Date: Wed, 11 Mar 2026 01:11:15 +0000 Subject: bpf: Fix undefined behavior in interpreter sdiv/smod for INT_MIN The BPF interpreter's signed 32-bit division and modulo handlers use the kernel abs() macro on s32 operands. The abs() macro documentation (include/linux/math.h) explicitly states the result is undefined when the input is the type minimum. When DST contains S32_MIN (0x80000000), abs((s32)DST) triggers undefined behavior and returns S32_MIN unchanged on arm64/x86. This value is then sign-extended to u64 as 0xFFFFFFFF80000000, causing do_div() to compute the wrong result. The verifier's abstract interpretation (scalar32_min_max_sdiv) computes the mathematically correct result for range tracking, creating a verifier/interpreter mismatch that can be exploited for out-of-bounds map value access. Introduce abs_s32() which handles S32_MIN correctly by casting to u32 before negating, avoiding signed overflow entirely. Replace all 8 abs((s32)...) call sites in the interpreter's sdiv32/smod32 handlers. s32 is the only affected case -- the s64 division/modulo handlers do not use abs(). Fixes: ec0e2da95f72 ("bpf: Support new signed div/mod instructions.") Acked-by: Yonghong Song Acked-by: Mykyta Yatsenko Signed-off-by: Jenny Guanni Qu Link: https://lore.kernel.org/r/20260311011116.2108005-2-qguanni@gmail.com Signed-off-by: Alexei Starovoitov --- kernel/bpf/core.c | 22 ++++++++++++++-------- 1 file changed, 14 insertions(+), 8 deletions(-) (limited to 'kernel/bpf') diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c index 9e126be33755..7b675a451ec8 100644 --- a/kernel/bpf/core.c +++ b/kernel/bpf/core.c @@ -1757,6 +1757,12 @@ bool bpf_opcode_in_insntable(u8 code) } #ifndef CONFIG_BPF_JIT_ALWAYS_ON +/* Absolute value of s32 without undefined behavior for S32_MIN */ +static u32 abs_s32(s32 x) +{ + return x >= 0 ? (u32)x : -(u32)x; +} + /** * ___bpf_prog_run - run eBPF program on a given context * @regs: is the array of MAX_BPF_EXT_REG eBPF pseudo-registers @@ -1921,8 +1927,8 @@ select_insn: DST = do_div(AX, (u32) SRC); break; case 1: - AX = abs((s32)DST); - AX = do_div(AX, abs((s32)SRC)); + AX = abs_s32((s32)DST); + AX = do_div(AX, abs_s32((s32)SRC)); if ((s32)DST < 0) DST = (u32)-AX; else @@ -1949,8 +1955,8 @@ select_insn: DST = do_div(AX, (u32) IMM); break; case 1: - AX = abs((s32)DST); - AX = do_div(AX, abs((s32)IMM)); + AX = abs_s32((s32)DST); + AX = do_div(AX, abs_s32((s32)IMM)); if ((s32)DST < 0) DST = (u32)-AX; else @@ -1976,8 +1982,8 @@ select_insn: DST = (u32) AX; break; case 1: - AX = abs((s32)DST); - do_div(AX, abs((s32)SRC)); + AX = abs_s32((s32)DST); + do_div(AX, abs_s32((s32)SRC)); if (((s32)DST < 0) == ((s32)SRC < 0)) DST = (u32)AX; else @@ -2003,8 +2009,8 @@ select_insn: DST = (u32) AX; break; case 1: - AX = abs((s32)DST); - do_div(AX, abs((s32)IMM)); + AX = abs_s32((s32)DST); + do_div(AX, abs_s32((s32)IMM)); if (((s32)DST < 0) == ((s32)IMM < 0)) DST = (u32)AX; else -- cgit v1.2.3 From c845894ebd6fb43226b3118d6b017942550910c5 Mon Sep 17 00:00:00 2001 From: Daniel Wade Date: Sat, 14 Mar 2026 13:15:20 +1100 Subject: bpf: Fix unsound scalar forking in maybe_fork_scalars() for BPF_OR maybe_fork_scalars() is called for both BPF_AND and BPF_OR when the source operand is a constant. When dst has signed range [-1, 0], it forks the verifier state: the pushed path gets dst = 0, the current path gets dst = -1. For BPF_AND this is correct: 0 & K == 0. For BPF_OR this is wrong: 0 | K == K, not 0. The pushed path therefore tracks dst as 0 when the runtime value is K, producing an exploitable verifier/runtime divergence that allows out-of-bounds map access. Fix this by passing env->insn_idx (instead of env->insn_idx + 1) to push_stack(), so the pushed path re-executes the ALU instruction with dst = 0 and naturally computes the correct result for any opcode. Fixes: bffacdb80b93 ("bpf: Recognize special arithmetic shift in the verifier") Signed-off-by: Daniel Wade Reviewed-by: Amery Hung Acked-by: Eduard Zingerman Link: https://lore.kernel.org/r/20260314021521.128361-2-danjwade95@gmail.com Signed-off-by: Alexei Starovoitov --- kernel/bpf/verifier.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'kernel/bpf') diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 5c0e6809024f..62377bcb66fd 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -15999,7 +15999,7 @@ static int maybe_fork_scalars(struct bpf_verifier_env *env, struct bpf_insn *ins else return 0; - branch = push_stack(env, env->insn_idx + 1, env->insn_idx, false); + branch = push_stack(env, env->insn_idx, env->insn_idx, false); if (IS_ERR(branch)) return PTR_ERR(branch); -- cgit v1.2.3 From bc308be380c136800e1e94c6ce49cb53141d6506 Mon Sep 17 00:00:00 2001 From: Daniel Borkmann Date: Thu, 19 Mar 2026 22:15:06 +0100 Subject: bpf: Fix sync_linked_regs regarding BPF_ADD_CONST32 zext propagation Jenny reported that in sync_linked_regs() the BPF_ADD_CONST32 flag is checked on known_reg (the register narrowed by a conditional branch) instead of reg (the linked target register created by an alu32 operation). Example case with reg: 1. r6 = bpf_get_prandom_u32() 2. r7 = r6 (linked, same id) 3. w7 += 5 (alu32 -- r7 gets BPF_ADD_CONST32, zero-extended by CPU) 4. if w6 < 0xFFFFFFFC goto safe (narrows r6 to [0xFFFFFFFC, 0xFFFFFFFF]) 5. sync_linked_regs() propagates to r7 but does NOT call zext_32_to_64() 6. Verifier thinks r7 is [0x100000001, 0x100000004] instead of [1, 4] Since known_reg above does not have BPF_ADD_CONST32 set above, zext_32_to_64() is never called on alu32-derived linked registers. This causes the verifier to track incorrect 64-bit bounds, while the CPU correctly zero-extends the 32-bit result. The code checking known_reg->id was correct however (see scalars_alu32_wrap selftest case), but the real fix needs to handle both directions - zext propagation should be done when either register has BPF_ADD_CONST32, since the linked relationship involves a 32-bit operation regardless of which side has the flag. Example case with known_reg (exercised also by scalars_alu32_wrap): 1. r1 = r0; w1 += 0x100 (alu32 -- r1 gets BPF_ADD_CONST32) 2. if r1 > 0x80 - known_reg = r1 (has BPF_ADD_CONST32), reg = r0 (doesn't) Hence, fix it by checking for (reg->id | known_reg->id) & BPF_ADD_CONST32. Moreover, sync_linked_regs() also has a soundness issue when two linked registers used different ALU widths: one with BPF_ADD_CONST32 and the other with BPF_ADD_CONST64. The delta relationship between linked registers assumes the same arithmetic width though. When one register went through alu32 (CPU zero-extends the 32-bit result) and the other went through alu64 (no zero-extension), the propagation produces incorrect bounds. Example: r6 = bpf_get_prandom_u32() // fully unknown if r6 >= 0x100000000 goto out // constrain r6 to [0, U32_MAX] r7 = r6 w7 += 1 // alu32: r7.id = N | BPF_ADD_CONST32 r8 = r6 r8 += 2 // alu64: r8.id = N | BPF_ADD_CONST64 if r7 < 0xFFFFFFFF goto out // narrows r7 to [0xFFFFFFFF, 0xFFFFFFFF] At the branch on r7, sync_linked_regs() runs with known_reg=r7 (BPF_ADD_CONST32) and reg=r8 (BPF_ADD_CONST64). The delta path computes: r8 = r7 + (delta_r8 - delta_r7) = 0xFFFFFFFF + (2 - 1) = 0x100000000 Then, because known_reg->id has BPF_ADD_CONST32, zext_32_to_64(r8) is called, truncating r8 to [0, 0]. But r8 used a 64-bit ALU op -- the CPU does NOT zero-extend it. The actual CPU value of r8 is 0xFFFFFFFE + 2 = 0x100000000, not 0. The verifier now underestimates r8's 64-bit bounds, which is a soundness violation. Fix sync_linked_regs() by skipping propagation when the two registers have mixed ALU widths (one BPF_ADD_CONST32, the other BPF_ADD_CONST64). Lastly, fix regsafe() used for path pruning: the existing checks used "& BPF_ADD_CONST" to test for offset linkage, which treated BPF_ADD_CONST32 and BPF_ADD_CONST64 as equivalent. Fixes: 7a433e519364 ("bpf: Support negative offsets, BPF_SUB, and alu32 for linked register tracking") Reported-by: Jenny Guanni Qu Co-developed-by: Puranjay Mohan Signed-off-by: Puranjay Mohan Signed-off-by: Daniel Borkmann Acked-by: Eduard Zingerman Link: https://lore.kernel.org/r/20260319211507.213816-1-daniel@iogearbox.net Signed-off-by: Alexei Starovoitov --- kernel/bpf/verifier.c | 21 +++++++++++++++------ 1 file changed, 15 insertions(+), 6 deletions(-) (limited to 'kernel/bpf') diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 62377bcb66fd..f108c01ff6d0 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -17415,6 +17415,12 @@ static void sync_linked_regs(struct bpf_verifier_env *env, struct bpf_verifier_s continue; if ((reg->id & ~BPF_ADD_CONST) != (known_reg->id & ~BPF_ADD_CONST)) continue; + /* + * Skip mixed 32/64-bit links: the delta relationship doesn't + * hold across different ALU widths. + */ + if (((reg->id ^ known_reg->id) & BPF_ADD_CONST) == BPF_ADD_CONST) + continue; if ((!(reg->id & BPF_ADD_CONST) && !(known_reg->id & BPF_ADD_CONST)) || reg->off == known_reg->off) { s32 saved_subreg_def = reg->subreg_def; @@ -17442,7 +17448,7 @@ static void sync_linked_regs(struct bpf_verifier_env *env, struct bpf_verifier_s scalar32_min_max_add(reg, &fake_reg); scalar_min_max_add(reg, &fake_reg); reg->var_off = tnum_add(reg->var_off, fake_reg.var_off); - if (known_reg->id & BPF_ADD_CONST32) + if ((reg->id | known_reg->id) & BPF_ADD_CONST32) zext_32_to_64(reg); reg_bounds_sync(reg); } @@ -19870,11 +19876,14 @@ static bool regsafe(struct bpf_verifier_env *env, struct bpf_reg_state *rold, * Also verify that new value satisfies old value range knowledge. */ - /* ADD_CONST mismatch: different linking semantics */ - if ((rold->id & BPF_ADD_CONST) && !(rcur->id & BPF_ADD_CONST)) - return false; - - if (rold->id && !(rold->id & BPF_ADD_CONST) && (rcur->id & BPF_ADD_CONST)) + /* + * ADD_CONST flags must match exactly: BPF_ADD_CONST32 and + * BPF_ADD_CONST64 have different linking semantics in + * sync_linked_regs() (alu32 zero-extends, alu64 does not), + * so pruning across different flag types is unsafe. + */ + if (rold->id && + (rold->id & BPF_ADD_CONST) != (rcur->id & BPF_ADD_CONST)) return false; /* Both have offset linkage: offsets must match */ -- cgit v1.2.3