[FFmpeg-devel] [PATCH 1/3] avformat/4xm: Cleanup on GET_LIST_HEADER() failure

[Michael Niedermayer]

On Sun, Jun 07, 2020 at 10:21:56PM +0200, Andreas Rheinhardt wrote:
> Michael Niedermayer:
> > Fixes: memleak
> > Fixes: 23142/clusterfuzz-testcase-minimized-ffmpeg_DEMUXER_fuzzer-5932860820422656
> > 
> > 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/4xm.c | 8 +++++---
> >  1 file changed, 5 insertions(+), 3 deletions(-)
> > 
> > diff --git a/libavformat/4xm.c b/libavformat/4xm.c
> > index aea9226984..5f0504b13e 100644
> > --- a/libavformat/4xm.c
> > +++ b/libavformat/4xm.c
> > @@ -59,8 +59,10 @@
> >  #define GET_LIST_HEADER() \
> >      fourcc_tag = avio_rl32(pb); \
> >      size       = avio_rl32(pb); \
> > -    if (fourcc_tag != LIST_TAG) \
> > -        return AVERROR_INVALIDDATA; \
> > +    if (fourcc_tag != LIST_TAG) { \
> > +        ret = AVERROR_INVALIDDATA; \
> > +        goto fail; \
> > +    } \
> >      fourcc_tag = avio_rl32(pb);
> >  
> >  typedef struct AudioTrack {
> > @@ -210,7 +212,7 @@ static int fourxm_read_header(AVFormatContext *s)
> >      unsigned int size;
> >      int header_size;
> >      FourxmDemuxContext *fourxm = s->priv_data;
> > -    unsigned char *header;
> > +    unsigned char *header = NULL;
> >      int i, ret;
> >  
> >      fourxm->track_count = 0;
> > 
> LGTM.

will apply

thx

> (Alternatively, one could av_freep header immediately after the loop
> before the second occurrence of GET_LIST_HEADER.)

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

Awnsering whenever a program halts or runs forever is
On a turing machine, in general impossible (turings halting problem).
On any real computer, always possible as a real computer has a finite number
of states N, and will either halt in less than N cycles or never halt.
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