[FFmpeg-devel] [PATCH 1/2] avformat/matroskadec: Check desc_bytes

[Andreas Rheinhardt]

Andreas Rheinhardt:
> Michael Niedermayer:
>> Fixes: Division by 0
>> Fixes: 44035/clusterfuzz-testcase-minimized-ffmpeg_dem_WEBM_DASH_MANIFEST_fuzzer-4826721386364928
>>
>> 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 5a9acfb247..f433391a16 100644
>> --- a/libavformat/matroskadec.c
>> +++ b/libavformat/matroskadec.c
>> @@ -4216,6 +4216,8 @@ static int64_t webm_dash_manifest_compute_bandwidth(AVFormatContext *s, int64_t
>>              do {
>>                  int64_t desc_bytes = desc_end.end_offset - desc_beg.start_offset;
>>                  int64_t desc_ns = desc_end.end_time_ns - desc_beg.start_time_ns;
>> +                if (desc_bytes <= 0)
>> +                    return -1;
>>                  double desc_sec = desc_ns / nano_seconds_per_second;
>>                  double calc_bits_per_second = (desc_bytes * 8) / desc_sec;
>>  
> 
> This should give a declaration-after-statement error.
> 

s/error/warning/

- Andreas