[FFmpeg-cvslog] avcodec/ac3dec_fixed: Fix runtime error: left shift of 419 by 23 places cannot be represented in type 'int'

[Michael Niedermayer]

ffmpeg | branch: release/2.8 | Michael Niedermayer <michael at niedermayer.cc> | Sun Jun  4 13:02:51 2017 +0200| [195b5b6cea072741f191f3c2ec981f5f606d6993] | committer: Michael Niedermayer

avcodec/ac3dec_fixed: Fix runtime error: left shift of 419 by 23 places cannot be represented in type 'int'

Fixes: 1352/clusterfuzz-testcase-minimized-5757565017260032

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 136ce8baa4fc16cf38690cb457f7356c00e00a28)
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=195b5b6cea072741f191f3c2ec981f5f606d6993
---

 libavcodec/ac3dec_fixed.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/libavcodec/ac3dec_fixed.c b/libavcodec/ac3dec_fixed.c
index 21756eac1b..d6dee6c5b3 100644
--- a/libavcodec/ac3dec_fixed.c
+++ b/libavcodec/ac3dec_fixed.c
@@ -69,7 +69,7 @@ static void scale_coefs (
     int temp, temp1, temp2, temp3, temp4, temp5, temp6, temp7;
 
     mul = (dynrng & 0x1f) + 0x20;
-    shift = 4 - ((dynrng << 23) >> 28);
+    shift = 4 - (sign_extend(dynrng, 9) >> 5);
     if (shift > 0 ) {
       round = 1 << (shift-1);
       for (i=0; i<len; i+=8) {