[FFmpeg-cvslog] avcodec/ac3dec_fixed: Fix integer overflow in scale_coefs()

[Michael Niedermayer]

ffmpeg | branch: release/3.0 | Michael Niedermayer <michael at niedermayer.cc> | Sun Jan 14 00:39:39 2018 +0100| [7d5ca21698112b0a9af49c6ac0023b29a2d959c8] | committer: Michael Niedermayer

avcodec/ac3dec_fixed: Fix integer overflow in scale_coefs()

Fixes: runtime error: signed integer overflow: 2147483520 + 128 cannot be represented in type 'int'
Fixes: 4800/clusterfuzz-testcase-minimized-6110372403609600

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 a1f38c75893c852cf19dcf3e4553549ba1e70950)
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=7d5ca21698112b0a9af49c6ac0023b29a2d959c8
---

 libavcodec/ac3dec_fixed.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/libavcodec/ac3dec_fixed.c b/libavcodec/ac3dec_fixed.c
index 56b62548ec..ef5fa5501a 100644
--- a/libavcodec/ac3dec_fixed.c
+++ b/libavcodec/ac3dec_fixed.c
@@ -64,8 +64,8 @@ static void scale_coefs (
     int dynrng,
     int len)
 {
-    int i, shift, round;
-    unsigned mul;
+    int i, shift;
+    unsigned mul, round;
     int temp, temp1, temp2, temp3, temp4, temp5, temp6, temp7;
 
     mul = (dynrng & 0x1f) + 0x20;