[FFmpeg-devel] [PATCH 2/3] avcodec/adpcm: Fix invalid shifts in ADPCM DTK

[Paul B Mahol]

Trivial change, LGTM

On 10/28/19, Michael Niedermayer <michael at niedermayer.cc> wrote:
> Fixes: left shift of negative value -1
> Fixes:
> 18397/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_ADPCM_DTK_fuzzer-5675653487132672
>
> 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/adpcm.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/libavcodec/adpcm.c b/libavcodec/adpcm.c
> index a8e74522b3..53d8d0be6a 100644
> --- a/libavcodec/adpcm.c
> +++ b/libavcodec/adpcm.c
> @@ -1723,7 +1723,7 @@ static int adpcm_decode_frame(AVCodecContext *avctx,
> void *data,
>                      else
>                          sampledat = sign_extend(byte >> 4, 4);
>
> -                    sampledat = (((sampledat << 12) >> (header & 0xf)) <<
> 6) + prev;
> +                    sampledat = ((sampledat * (1 << 12)) >> (header & 0xf))
> * (1 << 6) + prev;
>                      *samples++ = av_clip_int16(sampledat >> 6);
>                      c->status[channel].sample2 =
> c->status[channel].sample1;
>                      c->status[channel].sample1 = sampledat;
> --
> 2.23.0
>
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