[FFmpeg-devel] [PATCH v2] avformat/mov: abort reading truncated stts

[Gyan Doshi]

On 2021-12-21 02:18 am, Andreas Rheinhardt wrote:
> Gyan Doshi:
>> Avoids overreading the box and ingesting absurd values into stts_data
>> ---
>>   libavformat/mov.c | 5 +++++
>>   1 file changed, 5 insertions(+)
>>
>> diff --git a/libavformat/mov.c b/libavformat/mov.c
>> index 2aed6e80ef..5a7209837f 100644
>> --- a/libavformat/mov.c
>> +++ b/libavformat/mov.c
>> @@ -2935,6 +2935,11 @@ static int mov_read_stts(MOVContext *c, AVIOContext *pb, MOVAtom atom)
>>       avio_rb24(pb); /* flags */
>>       entries = avio_rb32(pb);
>>   
>> +    if (atom.size < 8 + (int64_t)entries*8) {
>> +        av_log(c->fc, AV_LOG_ERROR, "Truncated STTS box for st %d.\n", 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 might fix the issue with the fuzzer sample Michael gave you, but
> what would stop the fuzzer (or a malicious adversary) from simply using
> a gigantic atom size?

Do you want the comparison to switch to a strict inequality?

Regards,
Gyan