[Ffmpeg-devel] Maybe (?), robustness patch

[Mean]

Michael Niedermayer wrote:
> Hi
>
> On Sun, Jan 22, 2006 at 05:31:16PM +0000, Mean wrote:
>   
>> Hi,
>>    While trying to create a correct avcC atom with lavformat/x264, i've 
>> made some (interestingly ?) broken mp4 files.
>>    One of them makes lavcodec crash hard, which is bad and uncommon.
>>
>>    The problem is that in that case bit_length ends up being equal to 
>> -1, hence the crash a bit later
>>    I'm not sure it is a fix of great interest since such broken files 
>> should not exist at all, but anyway.
>>
>>    The trivial check that avoids the hard crash is below
>>
>>    One such funny file is available here
>>           
>> http://fixounet.free.fr/avidemux/win32/broken_h264_makes_lavcodec_crash.mp4
>>    No image, but no crash either.
>>
>> Thanks.
>>
>>
>>
>>    Index: h264.c
>> ===================================================================
>> --- h264.c      (revision 1724)
>> +++ h264.c      (working copy)
>> @@ -7458,7 +7458,13 @@
>>         ptr= decode_nal(h, buf + buf_index, &dst_length, &consumed, 
>> h->is_avc ? nalsize : buf_size - buf_index);
>>         if(ptr[dst_length - 1] == 0) dst_length--;
>>         bit_length= 8*dst_length - decode_rbsp_trailing(ptr + 
>> dst_length - 1);
>> -
>> +       /* MEANX */
>> +       if(bit_length<=0)
>> +       {
>> +                av_log(h->s.avctx, AV_LOG_ERROR, "h264: bit length 
>> computing error, broken stream ? \n");
>> +               return -1;
>> +       }
>> +       /* /MEANX */
>>     
>
> can you submit patches without addng your name to every chunk? just imagine
> how ffmpegs source would look like if everyone did this ...
>
> bit_length<0 also needs dst_length=0 and that already seems wrong ...
>
> [...]
>   
Hello,
       Sorry to be thick, but does that mean that a check for dst_length 
is also need or does that mean
    that it is of no interest ?
Thanks