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

[Andreas Rheinhardt]

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 -

- Andreas