linux-kernel - [PATCH AUTOSEL 6.14 631/642] bpf: abort verification if env->cur_state->loop

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Message-Id: <20250505221419.2672473-631-sashal@kernel.org>
Date: Mon,  5 May 2025 18:14:07 -0400
From: Sasha Levin <sashal@...nel.org>
To: linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Cc: Eduard Zingerman <eddyz87@...il.com>,
	Andrii Nakryiko <andrii.nakryiko@...il.com>,
	Andrii Nakryiko <andrii@...nel.org>,
	Alexei Starovoitov <ast@...nel.org>,
	Sasha Levin <sashal@...nel.org>,
	daniel@...earbox.net,
	bpf@...r.kernel.org
Subject: [PATCH AUTOSEL 6.14 631/642] bpf: abort verification if env->cur_state->loop_entry != NULL

From: Eduard Zingerman <eddyz87@...il.com>

[ Upstream commit f3c2d243a36ef23be07bc2bce7c6a5cb6e07d9e3 ]

In addition to warning abort verification with -EFAULT.
If env->cur_state->loop_entry != NULL something is irrecoverably
buggy.

Fixes: bbbc02b7445e ("bpf: copy_verifier_state() should copy 'loop_entry' field")
Suggested-by: Andrii Nakryiko <andrii.nakryiko@...il.com>
Signed-off-by: Eduard Zingerman <eddyz87@...il.com>
Acked-by: Andrii Nakryiko <andrii@...nel.org>
Link: https://lore.kernel.org/r/20250225003838.135319-1-eddyz87@gmail.com
Signed-off-by: Alexei Starovoitov <ast@...nel.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 kernel/bpf/verifier.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 4392436ba7511..1841467c4f2e5 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -19265,8 +19265,10 @@ static int do_check(struct bpf_verifier_env *env)
 						return err;
 					break;
 				} else {
-					if (WARN_ON_ONCE(env->cur_state->loop_entry))
-						env->cur_state->loop_entry = NULL;
+					if (WARN_ON_ONCE(env->cur_state->loop_entry)) {
+						verbose(env, "verifier bug: env->cur_state->loop_entry != NULL\n");
+						return -EFAULT;
+					}
 					do_print_state = true;
 					continue;
 				}
-- 
2.39.5