Re: [FFmpeg-devel] [PATCH 3/5] avformat/mov: Better check for duplicate iloc

[Vignesh Venkatasubramanian <vigneshv-at-google.com@ffmpeg.org>]

On Mon, Apr 17, 2023 at 4:18 PM Michael Niedermayer
<michael@niedermayer.cc> wrote:
>
> On Mon, Apr 17, 2023 at 12:36:26PM +0200, Anton Khirnov wrote:
> > Quoting Michael Niedermayer (2023-04-17 00:25:16)
> > > Fixes: memleak
> > > Fixes: 45982/clusterfuzz-testcase-minimized-ffmpeg_DEMUXER_fuzzer-6674082962997248
> > >
> > > Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
> > > Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
> > > ---
> > >  libavformat/mov.c | 2 +-
> > >  1 file changed, 1 insertion(+), 1 deletion(-)
> > >
> > > diff --git a/libavformat/mov.c b/libavformat/mov.c
> > > index 057fd872b10..6853bb324cf 100644
> > > --- a/libavformat/mov.c
> > > +++ b/libavformat/mov.c
> > > @@ -7777,7 +7777,7 @@ static int mov_read_iloc(MOVContext *c, AVIOContext *pb, MOVAtom atom)
> > >          return 0;
> > >      }
> > >
> > > -    if (c->fc->nb_streams) {
> > > +    if (c->fc->nb_streams || c->avif_info) {
> >
> > This first condition is now redundant, is it not?
>
> Iam not sure

I think the second condition alone should be enough here. Either way,
lgtm (if the current patch is more clearer for readers).

> what exactly happens if a trak occurs before
>

If a trak occurs before, then the condition in the line above should
take care of that case (!c->is_still_picture_avif). Because if a trak
was found, it will not be considered a still picture.

> Iam also not sure what happens if multiple meta tags occur triggering
> the avif stream addition, i may be missing something but the code seems
> not to expect that
>

Multiple meta tags are not allowed in the AVIF/HEIF specification.


> Adding the author of this code to CC
>
> thx
>
> [...]
>
> --
> Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
>
> In a rich man's house there is no place to spit but his face.
> -- Diogenes of Sinope



--
Vignesh
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