* [PATCH bpf-next] bpf: drop unnecessary user-triggerable WARN_ONCE in verifierl log
@ 2023-05-16 18:04 Andrii Nakryiko
2023-05-17 5:40 ` patchwork-bot+netdevbpf
0 siblings, 1 reply; 2+ messages in thread
From: Andrii Nakryiko @ 2023-05-16 18:04 UTC (permalink / raw)
To: bpf, ast, daniel, martin.lau
Cc: andrii, kernel-team, syzbot+8b2a08dfbd25fd933d75
It's trivial for user to trigger "verifier log line truncated" warning,
as verifier has a fixed-sized buffer of 1024 bytes (as of now), and there are at
least two pieces of user-provided information that can be output through
this buffer, and both can be arbitrarily sized by user:
- BTF names;
- BTF.ext source code lines strings.
Verifier log buffer should be properly sized for typical verifier state
output. But it's sort-of expected that this buffer won't be long enough
in some circumstances. So let's drop the check. In any case code will
work correctly, at worst truncating a part of a single line output.
Reported-by: syzbot+8b2a08dfbd25fd933d75@syzkaller.appspotmail.com
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
---
kernel/bpf/log.c | 3 ---
1 file changed, 3 deletions(-)
diff --git a/kernel/bpf/log.c b/kernel/bpf/log.c
index 046ddff37a76..850494423530 100644
--- a/kernel/bpf/log.c
+++ b/kernel/bpf/log.c
@@ -62,9 +62,6 @@ void bpf_verifier_vlog(struct bpf_verifier_log *log, const char *fmt,
n = vscnprintf(log->kbuf, BPF_VERIFIER_TMP_LOG_SIZE, fmt, args);
- WARN_ONCE(n >= BPF_VERIFIER_TMP_LOG_SIZE - 1,
- "verifier log line truncated - local buffer too short\n");
-
if (log->level == BPF_LOG_KERNEL) {
bool newline = n > 0 && log->kbuf[n - 1] == '\n';
--
2.34.1
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH bpf-next] bpf: drop unnecessary user-triggerable WARN_ONCE in verifierl log
2023-05-16 18:04 [PATCH bpf-next] bpf: drop unnecessary user-triggerable WARN_ONCE in verifierl log Andrii Nakryiko
@ 2023-05-17 5:40 ` patchwork-bot+netdevbpf
0 siblings, 0 replies; 2+ messages in thread
From: patchwork-bot+netdevbpf @ 2023-05-17 5:40 UTC (permalink / raw)
To: Andrii Nakryiko
Cc: bpf, ast, daniel, martin.lau, kernel-team, syzbot+8b2a08dfbd25fd933d75
Hello:
This patch was applied to bpf/bpf-next.git (master)
by Alexei Starovoitov <ast@kernel.org>:
On Tue, 16 May 2023 11:04:09 -0700 you wrote:
> It's trivial for user to trigger "verifier log line truncated" warning,
> as verifier has a fixed-sized buffer of 1024 bytes (as of now), and there are at
> least two pieces of user-provided information that can be output through
> this buffer, and both can be arbitrarily sized by user:
> - BTF names;
> - BTF.ext source code lines strings.
>
> [...]
Here is the summary with links:
- [bpf-next] bpf: drop unnecessary user-triggerable WARN_ONCE in verifierl log
https://git.kernel.org/bpf/bpf-next/c/cff36398bd4c
You are awesome, thank you!
--
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html
^ permalink raw reply [flat|nested] 2+ messages in thread
end of thread, other threads:[~2023-05-17 5:40 UTC | newest]
Thread overview: 2+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2023-05-16 18:04 [PATCH bpf-next] bpf: drop unnecessary user-triggerable WARN_ONCE in verifierl log Andrii Nakryiko
2023-05-17 5:40 ` patchwork-bot+netdevbpf
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.