[FFmpeg-cvslog] avformat/mxfdec: Fix file position addition

[Michael Niedermayer]

ffmpeg | branch: release/4.4 | Michael Niedermayer <michael at niedermayer.cc> | Mon Feb  1 19:59:55 2021 +0100| [f0d9b5899ae4c4f6bd58a1cd662e89d4b10a9619] | committer: Michael Niedermayer

avformat/mxfdec: Fix file position addition

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>
(cherry picked from commit f7c3484b2659063043100e8194d5790d2aa1a73c)
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=f0d9b5899ae4c4f6bd58a1cd662e89d4b10a9619
---

 libavformat/mxfdec.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/libavformat/mxfdec.c b/libavformat/mxfdec.c
index 1f372affcb..840484b37e 100644
--- a/libavformat/mxfdec.c
+++ b/libavformat/mxfdec.c
@@ -2903,7 +2903,7 @@ static int mxf_read_local_tags(MXFContext *mxf, KLVPacket *klv, MXFMetadataReadF
         meta = NULL;
         ctx  = mxf;
     }
-    while (avio_tell(pb) + 4 < klv_end && !avio_feof(pb)) {
+    while (avio_tell(pb) + 4ULL < klv_end && !avio_feof(pb)) {
         int ret;
         int tag = avio_rb16(pb);
         int size = avio_rb16(pb); /* KLV specified by 0x53 */