[FFmpeg-devel] [PATCH 1/7] avformat/asfdec_o: shrink extradata to the initialized size

[Michael Niedermayer]

On Fri, Apr 23, 2021 at 08:00:16PM +0200, Andreas Rheinhardt wrote:
> Michael Niedermayer:
> > Fixes: OOM
> > Fixes: 27240/clusterfuzz-testcase-minimized-ffmpeg_dem_ASF_O_fuzzer-5937469859823616
> > 
> > Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
> > Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
> > ---
> >  libavformat/asfdec_o.c | 6 +++++-
> >  1 file changed, 5 insertions(+), 1 deletion(-)
> > 
> > diff --git a/libavformat/asfdec_o.c b/libavformat/asfdec_o.c
> > index 6cfcd8b088..d08a09c14d 100644
> > --- a/libavformat/asfdec_o.c
> > +++ b/libavformat/asfdec_o.c
> > @@ -600,8 +600,12 @@ static int parse_video_info(AVIOContext *pb, AVStream *st)
> >          memset(st->codecpar->extradata + st->codecpar->extradata_size , 0,
> >                 AV_INPUT_BUFFER_PADDING_SIZE);
> >          if ((ret = avio_read(pb, st->codecpar->extradata,
> > -                             st->codecpar->extradata_size)) < 0)
> > +                             st->codecpar->extradata_size)) < 0) {
> > +            st->codecpar->extradata_size = 0;
> > +            av_freep(&st->codecpar->extradata);
> >              return ret;
> > +        }
> > +        st->codecpar->extradata_size = ret;
> >      }
> >      return 0;
> >  }
> > 
> How important is it to preserve partially read extradata? If it is not
> important, one could just use ff_get_extradata(); if it is important,
> then memset should be performed after the read, so that the real padding
> of the extradata is zeroed (it is uninitialized with your patch if the
> desired size could not be read).

i guess its not important to preserve, will apply with ff_get_extradata()

thanks

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

"I am not trying to be anyone's saviour, I'm trying to think about the
 future and not be sad" - Elon Musk

-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 195 bytes
Desc: not available
URL: <https://ffmpeg.org/pipermail/ffmpeg-devel/attachments/20210424/8017bcea/attachment.sig>