[FFmpeg-devel] [PATCH 1/2] avcodec/avpacket: Use av_copy_packet_side_data() in av_packet_copy_props()

James Almer jamrial at gmail.com
Thu May 4 06:09:57 EEST 2017


On 5/3/2017 6:45 AM, Michael Niedermayer wrote:
> On Wed, May 03, 2017 at 12:46:29AM -0300, James Almer wrote:
>> On 5/3/2017 12:21 AM, Michael Niedermayer wrote:
>>> Fixes timeout
>>> Fixes: 1293/clusterfuzz-testcase-minimized-6054752074858496
>>>
>>> Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/targets/ffmpeg
>>> Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
>>> ---
>>>  libavcodec/avpacket.c | 3 +++
>>>  1 file changed, 3 insertions(+)
>>>
>>> diff --git a/libavcodec/avpacket.c b/libavcodec/avpacket.c
>>> index 4bf830bb8a..ff7ee730a4 100644
>>> --- a/libavcodec/avpacket.c
>>> +++ b/libavcodec/avpacket.c
>>> @@ -557,6 +557,9 @@ FF_ENABLE_DEPRECATION_WARNINGS
>>>      dst->flags                = src->flags;
>>>      dst->stream_index         = src->stream_index;
>>>  
>>> +    if (!dst->side_data_elems);
>>> +        return av_copy_packet_side_data(dst, src);.
>>
>> This is a deprecated function, so ideally you'd use something else.
> 
> av_copy_packet_side_data() isnt marked as deprecated in avcodec.h

It should be moved outside the relevant deprecation guards, then, or be
actually deprecated seeing it duplicates the functionality of the more
complete av_packet_copy_props (after its side data copying code is
optimized).

> 
> 
>>
>> How does this fixes the problem anyway? The code below copies the
>> packet's side data as well.
> 
> I suspect calling realloc() repetly to add 1 element each time is
> expensive in some cases like at least some memory debuggers/checkers
> 
> It should always be better to avoid repeatly reallocating
> 
> [...]
> 
> 
> 
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