[FFmpeg-devel] [PATCH 2/5] avcodec/cinepak: Skip empty frames

[Tomas Härdin]

tis 2018-04-17 klockan 02:13 +0200 skrev Michael Niedermayer:
> Speeds up decoding from 3 to 0.1 seconds for 6302/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_CINEPAK_fuzzer-5626371985375232
> Fixes: Timeout
> 
> 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/cinepak.c | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/libavcodec/cinepak.c b/libavcodec/cinepak.c
> index ba0589582f..17e3afc35c 100644
> --- a/libavcodec/cinepak.c
> +++ b/libavcodec/cinepak.c
> @@ -444,6 +444,7 @@ static int cinepak_decode_frame(AVCodecContext *avctx,
>      const uint8_t *buf = avpkt->data;
>      int ret = 0, buf_size = avpkt->size;
>      CinepakContext *s = avctx->priv_data;
> +    int num_strips;
>  
>      s->data = buf;
>      s->size = buf_size;
> @@ -451,6 +452,12 @@ static int cinepak_decode_frame(AVCodecContext *avctx,
>      if (s->size < 10)
>          return AVERROR_INVALIDDATA;
>  
> +    num_strips = AV_RB16 (&s->data[8]);
> +
> +    //Empty frame, do not waste time
> +    if (!num_strips)
> +        return buf_size;

Won't this break in case of palette changes?

/Tomas