[FFmpeg-devel] [PATCH 2/5] libavcodec/mvha: Check height before applying median predictor

[Paul B Mahol]

lgtm

On 2/9/20, Michael Niedermayer <michael at niedermayer.cc> wrote:
> Fixes: out of array read
> Fixes:
> 20495/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_MVHA_fuzzer-5711179129552896
>
> Found-by: continuous fuzzing process
> https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
> Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
> ---
>  libavcodec/mvha.c | 12 +++++++-----
>  1 file changed, 7 insertions(+), 5 deletions(-)
>
> diff --git a/libavcodec/mvha.c b/libavcodec/mvha.c
> index afe5e511f2..1ea3bb3d76 100644
> --- a/libavcodec/mvha.c
> +++ b/libavcodec/mvha.c
> @@ -256,12 +256,14 @@ static int decode_frame(AVCodecContext *avctx,
>
>          dst = frame->data[p] + (avctx->height - 1) * frame->linesize[p];
>          s->llviddsp.add_left_pred(dst, dst, width, 0);
> -        dst -= stride;
> -        lefttop = left = dst[0];
> -        for (int y = 1; y < avctx->height; y++) {
> -            s->llviddsp.add_median_pred(dst, dst + stride, dst, width,
> &left, &lefttop);
> -            lefttop = left = dst[0];
> +        if (avctx->height > 1) {
>              dst -= stride;
> +            lefttop = left = dst[0];
> +            for (int y = 1; y < avctx->height; y++) {
> +                s->llviddsp.add_median_pred(dst, dst + stride, dst, width,
> &left, &lefttop);
> +                lefttop = left = dst[0];
> +                dst -= stride;
> +            }
>          }
>      }
>
> --
> 2.17.1
>
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