[FFmpeg-devel] [PATCH] avcodec/decode: Clear format on ff_get_buffer() failure

[Michael Niedermayer]

On Tue, Mar 24, 2020 at 10:59:21AM +0100, Anton Khirnov wrote:
> Quoting Michael Niedermayer (2020-03-24 01:41:43)
> > Fixes: out of array access
> > Fixes: 21193/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_WAVPACK_fuzzer-5125168956702720
> > 
> > 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/decode.c | 1 +
> >  1 file changed, 1 insertion(+)
> > 
> > diff --git a/libavcodec/decode.c b/libavcodec/decode.c
> > index af6bb3f952..fb22ef0ef3 100644
> > --- a/libavcodec/decode.c
> > +++ b/libavcodec/decode.c
> > @@ -1972,6 +1972,7 @@ int ff_get_buffer(AVCodecContext *avctx, AVFrame *frame, int flags)
> >      if (ret < 0) {
> >          av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
> >          frame->width = frame->height = 0;
> > +        frame->format = -1;
> 
> This looks ad-hoc. And also unnecessary, since get_buffer_internal() is
> already calling av_frame_unref() on failure.
> Seems it's just missing the cleanup goto on ff_decode_frame_props()
> failure.

will post a patch to fix that cleanup but i have to say that i 
feel a bit uneasy that a fix to out of array access is "not forgetting
cleanup on any path"
Ill add a assert so if another path leads to this, it at least gets
stoped/clearly caught.

Thanks

-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

The greatest way to live with honor in this world is to be what we pretend
to be. -- Socrates
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