This is a note to let you know that I've just added the patch titled
bpf: drop unnecessary user-triggerable WARN_ONCE in verifierl log
to the 6.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
bpf-drop-unnecessary-user-triggerable-warn_once-in-v.patch
and it can be found in the queue-6.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 4350e2f0eea4178f3bb70baa675e31ad71759a97
Author: Andrii Nakryiko <andrii@xxxxxxxxxx>
Date: Tue May 16 11:04:09 2023 -0700
bpf: drop unnecessary user-triggerable WARN_ONCE in verifierl log
[ Upstream commit cff36398bd4c7d322d424433db437f3c3391c491 ]
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@xxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Andrii Nakryiko <andrii@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20230516180409.3549088-1-andrii@xxxxxxxxxx
Signed-off-by: Alexei Starovoitov <ast@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/kernel/bpf/log.c b/kernel/bpf/log.c
index 046ddff37a76d..850494423530e 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';
