[FFmpeg-devel] [PATCH] avformat/matroskadec: Check pre_ns

[Michael Niedermayer]

Fixes: division by 0
Fixes: 44615/clusterfuzz-testcase-minimized-ffmpeg_dem_WEBM_DASH_MANIFEST_fuzzer-6681108677263360

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
---
 libavformat/matroskadec.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/libavformat/matroskadec.c b/libavformat/matroskadec.c
index 31e5111225..91f3567692 100644
--- a/libavformat/matroskadec.c
+++ b/libavformat/matroskadec.c
@@ -4205,6 +4205,8 @@ static int64_t webm_dash_manifest_compute_bandwidth(AVFormatContext *s, int64_t
             // prebuffered.
             pre_bytes = desc_end.end_offset - desc_end.start_offset;
             pre_ns = desc_end.end_time_ns - desc_end.start_time_ns;
+            if (pre_ns <= 0)
+                return -1;
             pre_sec = pre_ns / nano_seconds_per_second;
             prebuffer_bytes +=
                 pre_bytes * ((temp_prebuffer_ns / nano_seconds_per_second) / pre_sec);
-- 
2.17.1