Re: [FFmpeg-devel] [PATCH 2/2] avcodec/hevc_ps: Dont leave invalid cpb_cnt_minus1 in the context

[Michael Niedermayer <michael@niedermayer.cc>]

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On Wed, Oct 18, 2023 at 03:17:41PM +0200, Andreas Rheinhardt wrote:
> Michael Niedermayer:
> > Fixes: index 32 out of bounds for type 'uint32_t [32]'
> > Fixes: 63003/clusterfuzz-testcase-minimized-ffmpeg_DEMUXER_fuzzer-4685160840560640
> > 
> > Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
> > Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
> > ---
> >  libavcodec/hevc_ps.c | 1 +
> >  1 file changed, 1 insertion(+)
> > 
> > diff --git a/libavcodec/hevc_ps.c b/libavcodec/hevc_ps.c
> > index a6b64b92e3..f4365ef5b5 100644
> > --- a/libavcodec/hevc_ps.c
> > +++ b/libavcodec/hevc_ps.c
> > @@ -421,6 +421,7 @@ static int decode_hrd(GetBitContext *gb, int common_inf_present,
> >              if (hdr->cpb_cnt_minus1[i] > 31) {
> >                  av_log(NULL, AV_LOG_ERROR, "nb_cpb %d invalid\n",
> >                         hdr->cpb_cnt_minus1[i]);
> > +                hdr->cpb_cnt_minus1[i] = 0;
> >                  return AVERROR_INVALIDDATA;
> >              }
> >          }
> 
> There is a second issue here: There can be truncation during the
> previous assignment, because cpb_cnt_minus1 is uint8_t. So this should
> be fixed by properly checking the value and only putting it in the
> parameter set after it has been validated (which also avoids having to
> reset it).

ok, will apply with that

thx

[...]
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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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