[FFmpeg-cvslog] avcodec/ulti: Check number of blocks at init

[Michael Niedermayer]

ffmpeg | branch: release/3.4 | Michael Niedermayer <michael at niedermayer.cc> | Mon Jan 15 19:03:48 2018 +0100| [540f4467c8258b29c52be4dc0506a83ac29888bc] | committer: Michael Niedermayer

avcodec/ulti: Check number of blocks at init

Fixes: Timeout
Fixes: 4832/clusterfuzz-testcase-4699096590843904

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
(cherry picked from commit 725353525e73bbe5b6b4d01528252675f2417a02)
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=540f4467c8258b29c52be4dc0506a83ac29888bc
---

 libavcodec/ulti.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/libavcodec/ulti.c b/libavcodec/ulti.c
index e6f4374981..9e4c088b10 100644
--- a/libavcodec/ulti.c
+++ b/libavcodec/ulti.c
@@ -50,6 +50,8 @@ static av_cold int ulti_decode_init(AVCodecContext *avctx)
     s->width = avctx->width;
     s->height = avctx->height;
     s->blocks = (s->width / 8) * (s->height / 8);
+    if (s->blocks == 0)
+        return AVERROR_INVALIDDATA;
     avctx->pix_fmt = AV_PIX_FMT_YUV410P;
     s->ulti_codebook = ulti_codebook;