[FFmpeg-devel] [PATCH 4/5] avformat/mxfdec: Check index_edit_rate

[Tomas Härdin]

mån 2024-04-08 klockan 21:46 +0200 skrev Marton Balint:
> 
> 
> On Mon, 8 Apr 2024, Tomas Härdin wrote:
> 
> > tor 2024-04-04 klockan 00:51 +0200 skrev Michael Niedermayer:
> > > Fixes: Assertion b >=0 failed at libavutil/mathematics.c:62
> > > Fixes: 67811/clusterfuzz-testcase-minimized-
> > > ffmpeg_dem_MXF_fuzzer-
> > > 5108429687422976
> > > 
> > > 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/mxfdec.c | 3 +++
> > >  1 file changed, 3 insertions(+)
> > > 
> > > diff --git a/libavformat/mxfdec.c b/libavformat/mxfdec.c
> > > index 04de4c1d5e3..233d614f783 100644
> > > --- a/libavformat/mxfdec.c
> > > +++ b/libavformat/mxfdec.c
> > > @@ -1264,6 +1264,9 @@ static int
> > > mxf_read_index_table_segment(void
> > > *arg, AVIOContext *pb, int tag, int
> > >      case 0x3F0B:
> > >          segment->index_edit_rate.num = avio_rb32(pb);
> > >          segment->index_edit_rate.den = avio_rb32(pb);
> > > +        if (segment->index_edit_rate.num <= 0 ||
> > > +            segment->index_edit_rate.den <= 0)
> > > +            return AVERROR_INVALIDDATA;
> > 
> > mxf_compute_index_tables() has a check for index_edit_rate that you
> > probably want to remove as well. It was introduced in c6fff3d, but
> > the
> > files it supposedly fixes aren't in FATE. We shouldn't encourage
> > broken
> > muxers.
> 
> I don't quite get what FATE has to do with it. And the samples
> mentioned 
> in the patch has valid index segment edit rates, only they are
> different 
> from the track edit rate, and the patch was intended to fix that
> case.

Then why does it check against 0/0?

/Tomas