[FFmpeg-devel] [PATCH 2/5] avcodec/vc1_block: Fix invalid left shift in vc1_decode_p_mb()

[Paul B Mahol]

lgtm

On 10/2/19, Michael Niedermayer <michael at niedermayer.cc> wrote:
> Fixes: left shift of negative value -6
> Fixes:
> 17810/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_VC1_fuzzer-5638541240958976
>
> 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/vc1_block.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/libavcodec/vc1_block.c b/libavcodec/vc1_block.c
> index fe7dbf8b1d..f1c9f41f30 100644
> --- a/libavcodec/vc1_block.c
> +++ b/libavcodec/vc1_block.c
> @@ -1481,7 +1481,7 @@ static int vc1_decode_p_mb(VC1Context *v)
>
> v->vc1dsp.vc1_inv_trans_8x8(v->block[v->cur_blk_idx][block_map[i]]);
>                      if (v->rangeredfrm)
>                          for (j = 0; j < 64; j++)
> -                            v->block[v->cur_blk_idx][block_map[i]][j] <<=
> 1;
> +                            v->block[v->cur_blk_idx][block_map[i]][j] *= 2;
>                      block_cbp   |= 0xF << (i << 2);
>                      block_intra |= 1 << i;
>                  } else if (is_coded[i]) {
> --
> 2.23.0
>
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