[FFmpeg-cvslog] avformat/vividas: check length in read_vblock()

[Michael Niedermayer]

ffmpeg | branch: master | Michael Niedermayer <michael at niedermayer.cc> | Wed Jun 12 14:49:11 2019 +0200| [d8716e3df9ee81909342b0b59f5b6eff052964fd] | committer: Michael Niedermayer

avformat/vividas: check length in read_vblock()

Fixes: out of array access
Fixes: 15166/clusterfuzz-testcase-minimized-ffmpeg_DEMUXER_fuzzer-5731062396747776

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=d8716e3df9ee81909342b0b59f5b6eff052964fd
---

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

diff --git a/libavformat/vividas.c b/libavformat/vividas.c
index 51fdb4a31e..753328245d 100644
--- a/libavformat/vividas.c
+++ b/libavformat/vividas.c
@@ -205,7 +205,7 @@ static uint8_t *read_vblock(AVIOContext *src, uint32_t *size,
     decode_block(tmp, tmp, 4, key, k2, align);
 
     n = get_v(tmp);
-    if (!n)
+    if (n < 4)
         return NULL;
 
     buf = av_malloc(n);