[FFmpeg-cvslog] avformat/mov: Extend data_size check in mov_read_udta_string()

[Michael Niedermayer]

ffmpeg | branch: master | Michael Niedermayer <michael at niedermayer.cc> | Sun Dec 13 00:08:46 2020 +0100| [74c4c539538e36d8df02de2484b045010d292f2c] | committer: Michael Niedermayer

avformat/mov: Extend data_size check in mov_read_udta_string()

Fixes: signed integer overflow: -2147483634 - 16 cannot be represented in type 'int'
Fixes: 28322/clusterfuzz-testcase-minimized-ffmpeg_dem_MOV_fuzzer-5711888402612224

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=74c4c539538e36d8df02de2484b045010d292f2c
---

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

diff --git a/libavformat/mov.c b/libavformat/mov.c
index f5e0c69ef3..1c07cff6b5 100644
--- a/libavformat/mov.c
+++ b/libavformat/mov.c
@@ -404,7 +404,7 @@ retry:
     if (c->itunes_metadata && atom.size > 8) {
         int data_size = avio_rb32(pb);
         int tag = avio_rl32(pb);
-        if (tag == MKTAG('d','a','t','a') && data_size <= atom.size) {
+        if (tag == MKTAG('d','a','t','a') && data_size <= atom.size && data_size >= 16) {
             data_type = avio_rb32(pb); // type
             avio_rb32(pb); // unknown
             str_size = data_size - 16;