Re: [FFmpeg-devel] [PATCH v2 2/2] avformat/mov: validate box size for stts

[Gyan Doshi <ffmpeg@gyani.pro>]

On 2021-12-23 03:04 am, Michael Niedermayer wrote:
> On Wed, Dec 22, 2021 at 06:17:28PM +0530, Gyan Doshi wrote:
>> ---
>>   libavformat/mov.c | 6 ++++++
>>   1 file changed, 6 insertions(+)
>>
>> diff --git a/libavformat/mov.c b/libavformat/mov.c
>> index 7de95b7ab0..1e44c74944 100644
>> --- a/libavformat/mov.c
>> +++ b/libavformat/mov.c
>> @@ -2969,6 +2969,12 @@ static int mov_read_stts(MOVContext *c, AVIOContext *pb, MOVAtom atom)
>>       avio_rb24(pb); /* flags */
>>       entries = avio_rb32(pb);
>>   
>> +    if (validate_box_size(c, atom, pb, avio_tell(pb)-8, 8+(int64_t)entries*8, 0)) {
>> +        av_log(c->fc, AV_LOG_ERROR, "Invalid or incomplete %s box in stream %d\n",
>> +               av_fourcc2str(atom.type), c->fc->nb_streams-1);
>> +       return AVERROR_INVALIDDATA;
>> +    }
>> +
>>       av_log(c->fc, AV_LOG_TRACE, "track[%u].stts.entries = %u\n",
>>               c->fc->nb_streams-1, entries);
>>   
> this breaks playback of
>
> ./ffplay H263_NM_f.mp4

Sent revised set.

However, do we need to allow this?

The file has multiple invalid boxes. gpac refuses to import it. vlc 
using its default mp4 demuxer does not open it, neither does wmp or firefox.
Seems only avformat users can open the file.

Regards,
Gyan
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