[FFmpeg-cvslog] avcodec/clearvideo: Check for 0 tile_shift

[Michael Niedermayer]

ffmpeg | branch: release/4.4 | Michael Niedermayer <michael at niedermayer.cc> | Mon Apr 19 16:46:08 2021 +0200| [a6bd1bdd12e95d7a3aa2fbcd57494f0d7b1f6dcb] | committer: Michael Niedermayer

avcodec/clearvideo: Check for 0 tile_shift

Fixes: shift exponent -1 is negative
Fixes: 33401/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_CLEARVIDEO_fuzzer-5908683596890112

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 63e75e09aef5836330a2786f0a9229ed82239e6b)
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=a6bd1bdd12e95d7a3aa2fbcd57494f0d7b1f6dcb
---

 libavcodec/clearvideo.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/libavcodec/clearvideo.c b/libavcodec/clearvideo.c
index 79ba88857c..b3ccb51334 100644
--- a/libavcodec/clearvideo.c
+++ b/libavcodec/clearvideo.c
@@ -722,8 +722,8 @@ static av_cold int clv_decode_init(AVCodecContext *avctx)
     }
 
     c->tile_shift = av_log2(c->tile_size);
-    if (1U << c->tile_shift != c->tile_size) {
-        av_log(avctx, AV_LOG_ERROR, "Tile size: %d, is not power of 2.\n", c->tile_size);
+    if (1U << c->tile_shift != c->tile_size || c->tile_shift < 1) {
+        av_log(avctx, AV_LOG_ERROR, "Tile size: %d, is not power of 2 > 1\n", c->tile_size);
         return AVERROR_INVALIDDATA;
     }