[FFmpeg-cvslog] avformat/mlvdec: Check avio_read()

[Michael Niedermayer]

ffmpeg | branch: release/2.8 | Michael Niedermayer <michael at niedermayer.cc> | Wed Dec 25 05:13:02 2024 +0100| [25fcd936d82091cd78cd4e45e68034307edd7210] | committer: Michael Niedermayer

avformat/mlvdec: Check avio_read()

Fixes: use-of-uninitialized-value
Fixes: 383170476/clusterfuzz-testcase-minimized-ffmpeg_dem_MLV_fuzzer-4696002884337664

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Reviewed-by: Peter Ross <pross at xvid.org>
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
(cherry picked from commit bb85423142103d694d97bad1967bd3dc55440e71)
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=25fcd936d82091cd78cd4e45e68034307edd7210
---

 libavformat/mlvdec.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/libavformat/mlvdec.c b/libavformat/mlvdec.c
index 0ed0cb11a2..75b9f12d11 100644
--- a/libavformat/mlvdec.c
+++ b/libavformat/mlvdec.c
@@ -79,13 +79,15 @@ static int check_file_header(AVIOContext *pb, uint64_t guid)
 static void read_string(AVFormatContext *avctx, AVIOContext *pb, const char *tag, unsigned size)
 {
     char * value = av_malloc(size + 1);
+    int ret;
+
     if (!value) {
         avio_skip(pb, size);
         return;
     }
 
-    avio_read(pb, value, size);
-    if (!value[0]) {
+    ret = avio_read(pb, value, size);
+    if (ret != size || !value[0]) {
         av_free(value);
         return;
     }