[FFmpeg-devel] [PATCH 2/5] avcodec/cbs_mpeg2: Change assertion from bytes to bits

[Michael Niedermayer]

This allows writing empty slices

Fixes: Assertion slice->data_bit_start >= 0 && slice->data_size > slice->data_bit_start / 8 failed at libavcodec/cbs_mpeg2.c:340
Fixes: 19280/clusterfuzz-testcase-minimized-ffmpeg_BSF_MPEG2_METADATA_fuzzer-5632206173372416

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_mpeg2.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/libavcodec/cbs_mpeg2.c b/libavcodec/cbs_mpeg2.c
index 13d871cc89..b5286537db 100644
--- a/libavcodec/cbs_mpeg2.c
+++ b/libavcodec/cbs_mpeg2.c
@@ -337,7 +337,7 @@ static int cbs_mpeg2_write_slice(CodedBitstreamContext *ctx,
         uint8_t *pos = slice->data + slice->data_bit_start / 8;
 
         av_assert0(slice->data_bit_start >= 0 &&
-                   slice->data_size > slice->data_bit_start / 8);
+                   slice->data_size * 8LL >= slice->data_bit_start);
 
         if (slice->data_size * 8 + 8 > put_bits_left(pbc))
             return AVERROR(ENOSPC);
-- 
2.23.0