[FFmpeg-cvslog] avformat/mxfdec: Check llen addition for overflow

[Michael Niedermayer]

ffmpeg | branch: master | Michael Niedermayer <michael at niedermayer.cc> | Wed Dec 25 04:54:32 2024 +0100| [53db3516542c68f5ec92c5cdf8c13d76700ca9d5] | committer: Michael Niedermayer

avformat/mxfdec: Check llen addition for overflow

Fixes: signed integer overflow: 9223372036854775807 + 1 cannot be represented in type 'long'
Fixes: 377971441/clusterfuzz-testcase-minimized-ffmpeg_dem_MXF_fuzzer-4966030696316928

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=53db3516542c68f5ec92c5cdf8c13d76700ca9d5
---

 libavformat/mxfdec.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/libavformat/mxfdec.c b/libavformat/mxfdec.c
index 9ecaa287bb..0d97b3aade 100644
--- a/libavformat/mxfdec.c
+++ b/libavformat/mxfdec.c
@@ -496,6 +496,9 @@ static int klv_read_packet(MXFContext *mxf, KLVPacket *klv, AVIOContext *pb)
     if (length < 0)
         return length;
     klv->length = length;
+    if (klv->offset > INT64_MAX - 16 - llen)
+        return AVERROR_INVALIDDATA;
+
     pos = klv->offset + 16 + llen;
     if (pos > INT64_MAX - length)
         return AVERROR_INVALIDDATA;