[FFmpeg-devel] [PATCH 6/6] avformat/mvi: Check audio_data_size to be non negative

[James Almer]

On 4/10/2021 7:24 PM, Michael Niedermayer wrote:
> Fixes: left shift of negative value -224
> Fixes: 32144/clusterfuzz-testcase-minimized-ffmpeg_dem_MVI_fuzzer-4971479323246592
> 
> 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/mvi.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/libavformat/mvi.c b/libavformat/mvi.c
> index cfdbe5d273..10bf24408f 100644
> --- a/libavformat/mvi.c
> +++ b/libavformat/mvi.c
> @@ -73,7 +73,7 @@ static int read_header(AVFormatContext *s)
>       avio_rl16(pb);
>       avio_r8(pb);
>   
> -    if (frames_count == 0 || mvi->audio_data_size == 0)
> +    if (frames_count == 0 || (int)mvi->audio_data_size <= 0)

Make audio_data_size an int in MviDemuxContext instead of casting it 
here. Also, you could remove it from the context altogether, since it's 
only used in read_header().

>           return AVERROR_INVALIDDATA;
>   
>       if (version != 7 || player_version > 213) {
>