On 09/09/2011 03:09 PM, Alex Converse wrote:
> On Fri, Sep 9, 2011 at 12:03 PM, Laurent Aimar <fen...@elivagar.org> wrote:
>> Hi,
>>
>> On Fri, Sep 09, 2011 at 08:16:31AM +0200, Laurent Aimar wrote:
>>> On Fri, Sep 09, 2011 at 02:26:53AM +0200, Michael Niedermayer wrote:
>>>> On Fri, Sep 09, 2011 at 02:05:19AM +0200, Laurent Aimar wrote:
>>>> [...]
>>>>>>> @@ -311,7 +331,12 @@ static inline unsigned int get_bits1(GetBitContext
>>>>>>> *s){
>>>>>>> result <<= index & 7;
>>>>>>> result >>= 8 - 1;
>>>>>>> #endif
>>>>>>> +#ifndef UNCHECK_BITSTREAM_READER
>>>>>>> + if (index < s->size_in_bits)
>>>>>>> + index++;
>>>>>>> +#else
>>>>>>> index++;
>>>>>>> +#endif
>>>>>>
>>>>>> i think this will break error detection of some files with some
>>>>>> decoders because they detect it by an overread having happened
>>>>>>
>>>>>> also it might lead to infinite loops or other unexpected things
>>>>>> as some decoders depend on them
>>>>>> hitting zero padding after the buffer which is guranteed to lead to
>>>>>> vlc decoding failures for them as they have no valid all 0 vlc code
>>>>> I see. A simple way could be to simply add 8 * PADDING_SIZE to the check.
>>>>> I will add that locally.
>>>>
>>>> Iam not sure this is enough
>>>> the problematic case iam thinking of is a decoder that works with
>>>> slices, so the guranteed 0 padding would be farther away if the
>>>> current slice is not the last. mpeg1/2 should be examples of this
>>>> case
>>>>
>>>> maybe just returning 0 after size+something would work better
>>> I wanted to avoid the check while loading the cache, but you're right,
>>> it's probably the simplest solution to avoid the issue you mentionned.
>>> I will provide a patch to do that instead.
>>
>> New patch attached and it's a bit simpler.
>>
>> Now out of bound index is checked when reading the data and the value 0 is
>> returned in such cases. get_bits_count() will then return the real number
>> of bits read.
>>
>> I still have an issue with mpegaudio though. I will try to fix it first and
>> then I will do some benchmarks.
>>
>
> You also broke with the following fate tests:
>
> make: *** [fate-cljr] Error 1
> make: *** [fate-creatureshock-avs] Error 1
> make: *** [fate-ea-tqi-adpcm] Error 1
> make: *** [fate-indeo2] Error 1
> make: *** [fate-lossless-tta] Error 136
> make: *** [fate-motionpixels] Error 1
> make: *** [fate-wc3movie-xan] Error 139
> make: *** [fate-ac3-5.1] Error 1
damn. I thought I fixed all the ac3 fate samples, but apparently I
missed this one. It has an incomplete frame. The decoder still doesn't
read past the end of the buffer, just past the end of the bitstream reader.
> make: *** [fate-mp3-float-conf-compl] Error 1
> make: *** [fate-mp3-float-conf-si] Error 1
> make: *** [fate-vsynth1-ffv1] Error 1
> make: *** [fate-vsynth2-ffv1] Error 1
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