[FFmpeg-devel] [PATCH 3/4] avcodec/vp3: Check input amount in theora_decode_header()

[Michael Niedermayer]

On Sun, Jan 31, 2021 at 09:53:27AM +1100, Peter Ross wrote:
> On Sat, Jan 30, 2021 at 04:00:20PM +0100, Michael Niedermayer wrote:
> > Fixes: Timeout
> > Fixes: 29226/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_THEORA_fuzzer-6195092572471296
> > 
> > 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/vp3.c | 3 +++
> >  1 file changed, 3 insertions(+)
> > 
> > diff --git a/libavcodec/vp3.c b/libavcodec/vp3.c
> > index 2a1da6b062..57c6eb1ff9 100644
> > --- a/libavcodec/vp3.c
> > +++ b/libavcodec/vp3.c
> > @@ -2875,6 +2875,9 @@ static int theora_decode_header(AVCodecContext *avctx, GetBitContext *gb)
> >      int ret;
> >      AVRational fps, aspect;
> >  
> > +    if (get_bits_left(gb) < 206)
> > +        return AVERROR_INVALIDDATA;
> > +
> >      s->theora_header = 0;
> >      s->theora = get_bits(gb, 24);
> >      av_log(avctx, AV_LOG_DEBUG, "Theora bitstream version %X\n", s->theora);
> > -- 
> > 2.17.1
> 
> ok

will apply

thx

[...]

-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Awnsering whenever a program halts or runs forever is
On a turing machine, in general impossible (turings halting problem).
On any real computer, always possible as a real computer has a finite number
of states N, and will either halt in less than N cycles or never halt.
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