[FFmpeg-devel] [PATCH 1/2] avformat/mxfdec: Fix integer overflow in next position in mxf_read_local_tags()

[Michael Niedermayer]

Fixes: signed integer overflow: 9223372036854775723 + 8192 cannot be represented in type 'long'
Fixes: 29072/clusterfuzz-testcase-minimized-ffmpeg_dem_MXF_fuzzer-4812604904177664

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 | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/libavformat/mxfdec.c b/libavformat/mxfdec.c
index 4c932e954c..f1167761f9 100644
--- a/libavformat/mxfdec.c
+++ b/libavformat/mxfdec.c
@@ -2865,8 +2865,10 @@ static int mxf_read_local_tags(MXFContext *mxf, KLVPacket *klv, MXFMetadataReadF
         int ret;
         int tag = avio_rb16(pb);
         int size = avio_rb16(pb); /* KLV specified by 0x53 */
-        uint64_t next = avio_tell(pb) + size;
+        uint64_t next = avio_tell(pb);
         UID uid = {0};
+        if (next > INT64_MAX - size)
+            size = 0;
 
         av_log(mxf->fc, AV_LOG_TRACE, "local tag %#04x size %d\n", tag, size);
         if (!size) { /* ignore empty tag, needed for some files with empty UMID tag */
-- 
2.17.1