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

[Tomas Härdin]

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?

/Tomas