[FFmpeg-devel] [PATCH 2/2] avcodec/scpr: Check for min > max in decompress_p()

[Michael Niedermayer]

On Sun, Aug 05, 2018 at 10:08:31AM +0200, Paul B Mahol wrote:
> On 8/5/18, Michael Niedermayer <michael at niedermayer.cc> wrote:
> > Fixes: Timeout
> > Fixes:
> > 9342/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_SCPR_fuzzer-4795990841229312
> >
> > 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/scpr.c | 3 +++
> >  1 file changed, 3 insertions(+)
> >
> > diff --git a/libavcodec/scpr.c b/libavcodec/scpr.c
> > index 72f59d5917..d1e47b09ac 100644
> > --- a/libavcodec/scpr.c
> > +++ b/libavcodec/scpr.c
> > @@ -525,6 +525,9 @@ static int decompress_p(AVCodecContext *avctx,
> >      if (ret < 0)
> >          return ret;
> >
> > +    if (min > max)
> > +        return AVERROR_INVALIDDATA;
> > +
> 
> Shouldn't this check be actually bellow?

yes, fixed, locally


> You sure this does not break valid files?

i found no file that it breaks, beyond this, no iam not sure.
It mostly based on logic thinking that these would not be ordered the
other way, as that seems not usefull

Is there some specification or more files i can test ?


[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Rewriting code that is poorly written but fully understood is good.
Rewriting code that one doesnt understand is a sign that one is less smart
then the original author, trying to rewrite it will not make it better.
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