[FFmpeg-devel] [PATCH 4/8] avformat/mxfdec: Fix file position addition

[James Almer]

On 2/4/2021 3:43 PM, Tomas Härdin wrote:
> mån 2021-02-01 klockan 23:31 +0100 skrev Michael Niedermayer:
>> Not sure this is the best solution, maybe a more general solution
>> limiting the avio_tell() output to less than 63bit would be a better
>> option
> 
> Probably, since this is likely to happen in more places
> 
>> Fixes: signed integer overflow: 9223372036854775805 + 4 cannot be represented in type 'long'
>> Fixes: 29927/clusterfuzz-testcase-minimized-ffmpeg_dem_MXF_fuzzer-5579985228267520
>>
>> 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, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/libavformat/mxfdec.c b/libavformat/mxfdec.c
>> index afff20402d..97a1b749fe 100644
>> --- a/libavformat/mxfdec.c
>> +++ b/libavformat/mxfdec.c
>> @@ -2861,7 +2861,7 @@ static int mxf_read_local_tags(MXFContext *mxf, KLVPacket *klv, MXFMetadataReadF
>>           return AVERROR(ENOMEM);
>>       if (ctx_size)
>>           mxf_metadataset_init(ctx, type);
>> -    while (avio_tell(pb) + 4 < klv_end && !avio_feof(pb)) {
>> +    while (avio_tell(pb) + (uint64_t)4 < klv_end && !avio_feof(pb)) {
> 
> Why not cast avio_tell() instead?

Or use 4ULL

> 
> /Tomas
> 
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