[FFmpeg-devel] [PATCH 5/7] avformat/mvdec: Sanity check SAMPLE_WIDTH

[Peter Ross]

On Wed, Feb 03, 2021 at 12:13:32AM +0100, Michael Niedermayer wrote:
> Fixes: signed integer overflow: 999999999 * 8 cannot be represented in type 'int'
> Fixes: 30048/clusterfuzz-testcase-minimized-ffmpeg_dem_MV_fuzzer-5864289917337600
> 
> 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/mvdec.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/libavformat/mvdec.c b/libavformat/mvdec.c
> index d8f121bea5..ac96e4a808 100644
> --- a/libavformat/mvdec.c
> +++ b/libavformat/mvdec.c
> @@ -159,7 +159,10 @@ static int parse_audio_var(AVFormatContext *avctx, AVStream *st,
>          st->codecpar->sample_rate = var_read_int(pb, size);
>          avpriv_set_pts_info(st, 33, 1, st->codecpar->sample_rate);
>      } else if (!strcmp(name, "SAMPLE_WIDTH")) {
> -        st->codecpar->bits_per_coded_sample = var_read_int(pb, size) * 8;
> +        uint64_t bpc = var_read_int(pb, size) * (uint64_t)8;
> +        if (bpc > 100)
> +            return AVERROR_INVALIDDATA;
> +        st->codecpar->bits_per_coded_sample = bpc;
>      } else
>          return AVERROR_INVALIDDATA;

ok

could tighten it further.  realistically (audio) bits per codeded sample will never >16 here.

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