Re: [FFmpeg-devel] [PATCH 3/3] avcodec/evc_parse: Check tid

From: Michael Niedermayer <michael@niedermayer.cc>
To: FFmpeg development discussions and patches <ffmpeg-devel@ffmpeg.org>
Subject: Re: [FFmpeg-devel] [PATCH 3/3] avcodec/evc_parse: Check tid
Date: Tue, 31 Oct 2023 23:00:20 +0100
Message-ID: <20231031220020.GV3543730@pb2> (raw)
In-Reply-To: <013f01da08d5$d6920140$83b603c0$@samsung.com>

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On Fri, Oct 27, 2023 at 03:02:27PM +0200, Dawid Kozinski/Multimedia (PLT) /SRPOL/Staff Engineer/Samsung Electronics wrote:
> 
> 
> 
> 
> > -----Original Message-----
> > From: ffmpeg-devel <ffmpeg-devel-bounces@ffmpeg.org> On Behalf Of
> > Michael Niedermayer
> > Sent: piątek, 13 października 2023 01:28
> > To: FFmpeg development discussions and patches <ffmpeg-devel@ffmpeg.org>
> > Subject: [FFmpeg-devel] [PATCH 3/3] avcodec/evc_parse: Check tid
> > 
> > The check is based on not infinite looping. It is likely a more strict
> check can be
> > done
> > 
> > Fixes: Infinite loop
> > Fixes: 62473/clusterfuzz-testcase-minimized-
> > ffmpeg_BSF_EVC_FRAME_MERGE_fuzzer-5719883750703104
> > Fixes: 62765/clusterfuzz-testcase-minimized-ffmpeg_dem_EVC_fuzzer-
> > 6448531252314112
> > 
> > Found-by: continuous fuzzing process
> > https://protect2.fireeye.com/v1/url?k=06e4faf3-676fefea-06e571bc-
> > 74fe485cbfec-11816a289a0e9c00&q=1&e=16696cd9-38c1-42d0-9196-
> > 8ad7c6d1d0d6&u=https%3A%2F%2Fgithub.com%2Fgoogle%2Foss-
> > fuzz%2Ftree%2Fmaster%2Fprojects%2Fffmpeg
> > Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
> > ---
> >  libavcodec/evc_parse.c | 3 +++
> >  1 file changed, 3 insertions(+)
> > 
> > diff --git a/libavcodec/evc_parse.c b/libavcodec/evc_parse.c index
> > 255706ce61..43b8dabf8b 100644
> > --- a/libavcodec/evc_parse.c
> > +++ b/libavcodec/evc_parse.c
> > @@ -174,6 +174,9 @@ int ff_evc_derive_poc(const EVCParamSets *ps, const
> > EVCParserSliceHeader *sh,
> >          } else {
> >              int SubGopLength = 1 << sps->log2_sub_gop_length;
> > 
> > +            if (tid > (SubGopLength > 1 ? 1 + av_log2(SubGopLength - 1) :
> 0))
> > +                return AVERROR_INVALIDDATA;
> > +
> >              if (tid == 0) {
> >                  poc->PicOrderCntVal = poc->prevPicOrderCntVal +
> SubGopLength;
> >                  poc->DocOffset = 0;
> > --
> 
> 
> Looks good

will apply

thx

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

The educated differ from the uneducated as much as the living from the
dead. -- Aristotle 

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