[FFmpeg-cvslog] avcodec/diracdec: Fix integer overflow in divide3()

[Michael Niedermayer]

ffmpeg | branch: release/3.1 | Michael Niedermayer <michael at niedermayer.cc> | Thu Jul 27 23:49:27 2017 +0200| [6b1c71040d170c66b20d214a17aacefc215cd9c5] | committer: Michael Niedermayer

avcodec/diracdec: Fix integer overflow in divide3()

Fixes: runtime error: signed integer overflow: -1073746548 * 21845 cannot be represented in type 'int'
Fixes: 2729/clusterfuzz-testcase-minimized-5902915464069120

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 c0220c768c7fc933a76c863ebbb0abdf68a88533)
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=6b1c71040d170c66b20d214a17aacefc215cd9c5
---

 libavcodec/diracdec.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/libavcodec/diracdec.c b/libavcodec/diracdec.c
index 160085f852..42518c2681 100644
--- a/libavcodec/diracdec.c
+++ b/libavcodec/diracdec.c
@@ -231,7 +231,7 @@ enum dirac_subband {
 /* magic number division by 3 from schroedinger */
 static inline int divide3(int x)
 {
-    return ((x+1)*21845 + 10922) >> 16;
+    return (int)((x+1U)*21845 + 10922) >> 16;
 }
 
 static DiracFrame *remove_frame(DiracFrame *framelist[], int picnum)