[FFmpeg-devel] [PATCH 2/6] avcodec/cbs: Do not assert on traces beyond 255 bits

[Michael Niedermayer]

Fixes: Assertion length < 256 failed at libavcodec/cbs.c:517
Fixes: 62673/clusterfuzz-testcase-minimized-ffmpeg_BSF_TRACE_HEADERS_fuzzer-6490971837431808

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
---
 libavcodec/cbs.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/libavcodec/cbs.c b/libavcodec/cbs.c
index cdd7adebebd..2f5d0334a2a 100644
--- a/libavcodec/cbs.c
+++ b/libavcodec/cbs.c
@@ -514,6 +514,11 @@ void ff_cbs_trace_read_log(void *trace_context,
 
     position = get_bits_count(gbc);
 
+    if (length >= 256) {
+        av_log(ctx->log_ctx, ctx->trace_level, "trace of %d bits truncated at 255\n", length);
+        length = 255;
+    }
+
     av_assert0(length < 256);
     for (i = 0; i < length; i++)
         bits[i] = get_bits1(gbc) ? '1' : '0';
-- 
2.17.1