[FFmpeg-devel] [PATCH 5/5] avformat/mpeg: Don't use unintialized value

[Michael Niedermayer]

On Sun, Jan 19, 2020 at 02:43:00PM +0000, Andreas Rheinhardt wrote:
> Michael Niedermayer:
> > On Tue, Oct 22, 2019 at 03:16:45PM +0200, Andreas Rheinhardt wrote:
> >> vobsub_read_packet() didn't check whether an index in array of AVPackets
> >> was valid and therefore used uninitialized values.
> >>
> >> Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt at gmail.com>
> >> ---
> >> Actually I only wanted to use Valgrind to check for memleaks...
> >>
> >>  libavformat/mpeg.c | 4 ++++
> >>  1 file changed, 4 insertions(+)
> >>
> >> diff --git a/libavformat/mpeg.c b/libavformat/mpeg.c
> >> index 73ade71d95..474afd06b9 100644
> >> --- a/libavformat/mpeg.c
> >> +++ b/libavformat/mpeg.c
> >> @@ -930,6 +930,10 @@ static int vobsub_read_packet(AVFormatContext *s, AVPacket *pkt)
> >>          FFDemuxSubtitlesQueue *tmpq = &vobsub->q[i];
> >>          int64_t ts;
> >>          av_assert0(tmpq->nb_subs);
> >> +
> >> +        if (tmpq->current_sub_idx >= tmpq->nb_subs)
> >> +            continue;
> > 
> > How can this issue be reproduced ?
> > 
> > thx
> > 
> > [...]
> 
> Read a VobSub subtitle till the end:
> ffmpeg -i <idx input file> -c copy -f null -

does not reproduce

./ffmpeg  -i fate/sub/vobsub.idx  -c copy   -f null -
Output file #0 does not contain any stream
code does not execute

./ffmpeg  -i fate/sub/vobsub.idx  -c copy -map s  -f null -
the if does not execute

iam obviously doing something wrong, can you provide a unambigous testcase?

Thanks

[...]
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Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

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