[FFmpeg-devel] [PATCH 03/11] avformat/mxfdec: Check type before setting sub_descriptors_refs

[Andreas Rheinhardt]

Tomas Härdin:
> tis 2020-10-20 klockan 22:56 +0200 skrev Michael Niedermayer:
>> Fixes: memleak
>> Fixes: 26352/clusterfuzz-testcase-minimized-ffmpeg_DEMUXER_fuzzer-5201158714687488
>>
>> Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
>> Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
>> ---
>>  libavformat/mxfdec.c | 2 ++
>>  1 file changed, 2 insertions(+)
>>
>> diff --git a/libavformat/mxfdec.c b/libavformat/mxfdec.c
>> index d16a7af0df..0313cf4a28 100644
>> --- a/libavformat/mxfdec.c
>> +++ b/libavformat/mxfdec.c
>> @@ -1172,6 +1172,8 @@ static int mxf_read_generic_descriptor(void *arg, AVIOContext *pb, int tag, int
>>  
>>      switch(tag) {
>>      case 0x3F01:
>> +        if (descriptor->type != MultipleDescriptor)
>> +            return AVERROR_INVALIDDATA;
>>          return mxf_read_strong_ref_array(pb, &descriptor->sub_descriptors_refs,
>>                                               &descriptor->sub_descriptors_count);
>>      case 0x3002: /* ContainerDuration */
> 
> mxf_read_strong_ref_array() is called in more places than this. A
> better solution would be to make freeing sub_descriptors_refs in
> mxf_free_metadataset() not depends on type
> 
But this is the only place that sets the sub_descriptors_ref.
Do the other tags that lead to certain properties being read (like
frame_layouts) actually make sense for a MultipleDescriptor? If not, why
do Descriptor and MultipleDescriptor share the same parsing function?

- Andreas