[FFmpeg-devel] [PATCH 3/3] avcodec/huffyuvdec: Check input buffer size

[Michael Niedermayer]

On Mon, Feb 05, 2018 at 10:04:47AM +0100, Paul B Mahol wrote:
> On 2/5/18, Michael Niedermayer <michael at niedermayer.cc> wrote:
> > On Thu, Feb 01, 2018 at 02:36:16AM +0100, Michael Niedermayer wrote:
> >> On Wed, Jan 31, 2018 at 07:56:06PM +0100, Paul B Mahol wrote:
> >> > On 1/31/18, Michael Niedermayer <michael at niedermayer.cc> wrote:
> >> > > Fixes: Timeout
> >> > > Fixes: 5487/clusterfuzz-testcase-4696837035393024
> >> > >
> >> > > 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/huffyuvdec.c | 3 +++
> >> > >  1 file changed, 3 insertions(+)
> >> > >
> >> > > diff --git a/libavcodec/huffyuvdec.c b/libavcodec/huffyuvdec.c
> >> > > index 979c4b9d5c..66357bfb40 100644
> >> > > --- a/libavcodec/huffyuvdec.c
> >> > > +++ b/libavcodec/huffyuvdec.c
> >> > > @@ -919,6 +919,9 @@ static int decode_frame(AVCodecContext *avctx,
> >> > > void
> >> > > *data, int *got_frame,
> >> > >      AVFrame *const p = data;
> >> > >      int table_size = 0, ret;
> >> > >
> >> > > +    if (buf_size < (width * height + 7)/8)
> >> > > +        return AVERROR_INVALIDDATA;
> >> > > +
> >> >
> >> > Are you sure this is enough?
> >>
> >> I dont know if thats the only way the decoder can be made to waste
> >> large amounts of CPU with little input data
> >>
> >> I do belive it stops this specific class of issues though
> >>
> >>
> >> >
> >> > Something similar you had already posted long ago.
> >>
> >> for other decoders, yes. Did i forget a patch for huffyuv ?
> >
> > i will apply this in a few days unless someone has objections or
> > sees some possible imrpovment
> 
> Are you sure this does not break decoding of valid files?

huffyuv encodes samples using huffman codes, the smallest is 1 bit so
w*h bits should be the minimum

Am i missing something ?


[...]
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Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

He who knows, does not speak. He who speaks, does not know. -- Lao Tsu
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