[FFmpeg-cvslog] avcodec/cllc: Check prefix

[Michael Niedermayer]

ffmpeg | branch: release/3.3 | Michael Niedermayer <michael at niedermayer.cc> | Tue May  9 19:38:46 2017 +0200| [70d3ad7b6fb79b17c44193e9de402496f51ae27a] | committer: Michael Niedermayer

avcodec/cllc: Check prefix

Fixes: runtime error: left shift of 1610706944 by 1 places cannot be represented in type 'int'
Fixes: 1421/clusterfuzz-testcase-minimized-6239947507892224

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/targets/ffmpeg
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
(cherry picked from commit 62c5949beca2c95d6af5c74985467438d2295a66)
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=70d3ad7b6fb79b17c44193e9de402496f51ae27a
---

 libavcodec/cllc.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/libavcodec/cllc.c b/libavcodec/cllc.c
index ec11fc34b0..fe9583796f 100644
--- a/libavcodec/cllc.c
+++ b/libavcodec/cllc.c
@@ -81,6 +81,10 @@ static int read_code_table(CLLCContext *ctx, GetBitContext *gb, VLC *vlc)
 
             count++;
         }
+        if (prefix > (65535 - 256)/2) {
+            vlc->table = NULL;
+            return AVERROR_INVALIDDATA;
+        }
 
         prefix <<= 1;
     }