[FFmpeg-devel] [PATCH 1/2] avcodec/cbs_av1_syntax_template: Set seen_frame_header only after successfull uncompressed_header()

[Michael Niedermayer]

On Sat, Dec 14, 2019 at 03:21:57PM -0300, James Almer wrote:
> On 12/14/2019 2:43 PM, Michael Niedermayer wrote:
> > Fixes: assertion failure
> > Fixes: 19301/clusterfuzz-testcase-minimized-ffmpeg_BSF_AV1_FRAME_MERGE_fuzzer-5743212006473728
> > 
> > Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
> > Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
> > ---
> >  libavcodec/cbs_av1_syntax_template.c | 4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> > 
> > diff --git a/libavcodec/cbs_av1_syntax_template.c b/libavcodec/cbs_av1_syntax_template.c
> > index 523f9359e4..01c180e4af 100644
> > --- a/libavcodec/cbs_av1_syntax_template.c
> > +++ b/libavcodec/cbs_av1_syntax_template.c
> > @@ -1601,8 +1601,6 @@ static int FUNC(frame_header_obu)(CodedBitstreamContext *ctx, RWContext *rw,
> >          else
> >              HEADER("Frame Header");
> >  
> > -        priv->seen_frame_header = 1;
> > -
> >  #ifdef READ
> >          start_pos = get_bits_count(rw);
> >  #else
> > @@ -1611,6 +1609,8 @@ static int FUNC(frame_header_obu)(CodedBitstreamContext *ctx, RWContext *rw,
> >  
> >          CHECK(FUNC(uncompressed_header)(ctx, rw, current));
> >  
> > +        priv->seen_frame_header = 1;
> > +
> >          if (current->show_existing_frame) {
> >              priv->seen_frame_header = 0;
> >          } else {
> 
> What's the assertion that fails? av_assert0(priv->frame_header_ref &&
> priv->frame_header)? If so, then if priv->frame_header_ref fails to be
> allocated and the error is ignored, the same assertion could trigger as
> seen_frame_header will be 1 even after this patch.
> 

> I think you can just remove the above line instead of moving it. Right
> below the call to uncompressed_header() it's going to be set to either 0
> or 1 anyway.

will apply with this suggestion

thx


> Another option could be replacing the assertion for a simple check for
> priv->frame_header_ref that returns invalid data if it's not set.
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Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

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