[FFmpeg-devel] [PATCH 1/2] avformat/wtvdec: Check len in parse_chunks() to avoid overflow

[Peter Ross]

On Mon, Feb 08, 2021 at 02:29:01PM +0100, Michael Niedermayer wrote:
> Fixes: signed integer overflow: 2147483647 + 7 cannot be represented in type 'int'
> Fixes: 30084/clusterfuzz-testcase-minimized-ffmpeg_dem_WTV_fuzzer-6192261941559296
> 
> 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/wtvdec.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/libavformat/wtvdec.c b/libavformat/wtvdec.c
> index 6c41e3c1a3..7def9d2348 100644
> --- a/libavformat/wtvdec.c
> +++ b/libavformat/wtvdec.c
> @@ -794,7 +794,7 @@ static int parse_chunks(AVFormatContext *s, int mode, int64_t seekts, int *len_p
>  
>          ff_get_guid(pb, &g);
>          len = avio_rl32(pb);
> -        if (len < 32) {
> +        if (len < 32 || len > INT_MAX - 7) {
>              int ret;
>              if (avio_feof(pb))
>                  return AVERROR_EOF;

the + 7 comes from WTV_PAD calculation
looks good

-- Peter
(A907 E02F A6E5 0CD2 34CD 20D2 6760 79C5 AC40 DD6B)