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

[Michael Niedermayer]

On Tue, Apr 17, 2018 at 10:36:40AM +0200, Tomas Härdin wrote:
> 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?

well, iam not even sure this branch occurs in real
world undamaged files but i think you are correct, it could potentially loose
a palette, ill fix this

Thanks

[...]
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Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

When you are offended at any man's fault, turn to yourself and study your
own failings. Then you will forget your anger. -- Epictetus
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