From: Eduard Zingerman Date: Fri, 19 Sep 2025 02:18:36 +0000 (-0700) Subject: bpf: remove redundant REG_LIVE_READ check in stacksafe() X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=12a23f93a50dad7f820ca4326c7e289e7e13fb9f;p=thirdparty%2Fkernel%2Fstable.git bpf: remove redundant REG_LIVE_READ check in stacksafe() stacksafe() is called in exact == NOT_EXACT mode only for states that had been porcessed by clean_verifier_states(). The latter replaces dead stack spills with a series of STACK_INVALID masks. Such masks are already handled by stacksafe(). Signed-off-by: Eduard Zingerman Link: https://lore.kernel.org/r/20250918-callchain-sensitive-liveness-v3-3-c3cd27bacc60@gmail.com Signed-off-by: Alexei Starovoitov --- diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 64186ea0839be..74a96a0d6c8a1 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -18785,13 +18785,6 @@ static bool stacksafe(struct bpf_verifier_env *env, struct bpf_func_state *old, cur->stack[spi].slot_type[i % BPF_REG_SIZE])) return false; - if (!(old->stack[spi].spilled_ptr.live & REG_LIVE_READ) - && exact == NOT_EXACT) { - i += BPF_REG_SIZE - 1; - /* explored state didn't use this */ - continue; - } - if (old->stack[spi].slot_type[i % BPF_REG_SIZE] == STACK_INVALID) continue;