[FFmpeg-devel] [PATCH 1/5] avformat/mxfdec: fix klv_decode_ber_length return value usage

[Marton Balint]

On Sun, 27 May 2018, Tomas Härdin wrote:

> sön 2018-05-27 klockan 21:21 +0200 skrev Marton Balint:
>>> Signed-off-by: Marton Balint <cus at passwd.hu>
>> ---
>>  libavformat/mxfdec.c | 15 ++++++++++++---
>>  1 file changed, 12 insertions(+), 3 deletions(-)
>>
>> diff --git a/libavformat/mxfdec.c b/libavformat/mxfdec.c
>> index 7a42555562..40c9e0c3a9 100644
>> --- a/libavformat/mxfdec.c
>> +++ b/libavformat/mxfdec.c
>> @@ -372,6 +372,8 @@ static int64_t klv_decode_ber_length(AVIOContext *pb)
>>          while (bytes_num--)
>>              size = size << 8 | avio_r8(pb);
>>      }
>> +    if (size > INT64_MAX)
>> +        return AVERROR_INVALIDDATA;
>>      return size;
>>  }
>>  
>> @@ -390,13 +392,17 @@ static int mxf_read_sync(AVIOContext *pb, const uint8_t *key, unsigned size)
>>  
>>  static int klv_read_packet(KLVPacket *klv, AVIOContext *pb)
>>  {
>> +    int64_t length;
>>      if (!mxf_read_sync(pb, mxf_klv_key, 4))
>>          return AVERROR_INVALIDDATA;
>>      klv->offset = avio_tell(pb) - 4;
>>      memcpy(klv->key, mxf_klv_key, 4);
>>      avio_read(pb, klv->key + 4, 12);
>> -    klv->length = klv_decode_ber_length(pb);
>> -    return klv->length == -1 ? -1 : 0;
>> +    length = klv_decode_ber_length(pb);
>> +    if (length < 0)
>> +        return length;
>> +    klv->length = length;
>> +    return 0;
>>  }
>
> This feels like the kind of thing that should have been caught ages
> ago. Are there any other -1's like this hiding in mxfdec? I took a
> quick look but didn't find much

The code was correct before bcd5d979aa377a16d7fa6b9993e269003281af5c 
because klv_decode_ber_length returned explict -1 back then.

Let's just hope no other place requires -1 error code, I can't seem to 
find similar cases either.

Thanks,
Marton