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>
---
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
