Re: [FFmpeg-devel] [PATCH 2/2] avcodec/h263dec: Avoid parsing extradata repeatedly

From: Michael Niedermayer <michael@niedermayer.cc>
To: FFmpeg development discussions and patches <ffmpeg-devel@ffmpeg.org>
Subject: Re: [FFmpeg-devel] [PATCH 2/2] avcodec/h263dec: Avoid parsing extradata repeatedly
Date: Mon, 21 Nov 2022 19:53:53 +0100
Message-ID: <20221121185353.GE710311@pb2> (raw)
In-Reply-To: <166903160666.26119.6366120610609027209@lain.khirnov.net>

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On Mon, Nov 21, 2022 at 12:53:26PM +0100, Anton Khirnov wrote:
> Quoting Michael Niedermayer (2022-11-18 00:14:18)
> > Fixes: Timeout
> > Fixes: 52329/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_MPEG4_fuzzer-4716563886637056
> > 
> > Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
> > Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
> > ---
> >  libavcodec/h263dec.c   | 3 ++-
> >  libavcodec/mpegvideo.h | 1 +
> >  2 files changed, 3 insertions(+), 1 deletion(-)
> > 
> > diff --git a/libavcodec/h263dec.c b/libavcodec/h263dec.c
> > index 71b846ba74..4eab43d939 100644
> > --- a/libavcodec/h263dec.c
> > +++ b/libavcodec/h263dec.c
> > @@ -492,11 +492,12 @@ retry:
> >      } else if (CONFIG_MSMPEG4DEC && s->msmpeg4_version) {
> >          ret = ff_msmpeg4_decode_picture_header(s);
> >      } else if (CONFIG_MPEG4_DECODER && avctx->codec_id == AV_CODEC_ID_MPEG4) {
> > -        if (s->avctx->extradata_size && s->picture_number == 0) {
> > +        if (s->avctx->extradata_size && s->picture_number == 0 && !s->extradata_parsed) {
> 
> Wouldn't it make sense to get rid of the picture_number condition now?

I was thinking about droping it too. I dont know why i didnt, you are correct

thx

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