[FFmpeg-cvslog] avformat/mxg: clear AV_INPUT_BUFFER_PADDING_SIZE

[Michael Niedermayer]

ffmpeg | branch: master | Michael Niedermayer <michael at niedermayer.cc> | Thu Jul 24 01:05:40 2025 +0200| [1b12e919cfe3bf69038225794330d14575fb78d0] | committer: Michael Niedermayer

avformat/mxg: clear AV_INPUT_BUFFER_PADDING_SIZE

Fixes: use of uninitialized memory
Fixes: 427532813/clusterfuzz-testcase-minimized-ffmpeg_dem_MXG_fuzzer-5661938917113856

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=1b12e919cfe3bf69038225794330d14575fb78d0
---

 libavformat/mxg.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/libavformat/mxg.c b/libavformat/mxg.c
index 6a39873f21..40139d7d3d 100644
--- a/libavformat/mxg.c
+++ b/libavformat/mxg.c
@@ -127,6 +127,8 @@ static int mxg_update_cache(AVFormatContext *s, unsigned int cache_size)
 
     mxg->cache_size += ret;
 
+    memset(mxg->buffer_ptr + mxg->cache_size, 0, AV_INPUT_BUFFER_PADDING_SIZE);
+
     return ret;
 }