[FFmpeg-cvslog] avcodec/alacdsp: fix integer overflow in decorrelate_stereo()

[Michael Niedermayer]

ffmpeg | branch: release/3.4 | Michael Niedermayer <michael at niedermayer.cc> | Thu Jul 23 23:34:15 2020 +0200| [50b56b539ec534d661cf1ffb2b4fbc8cb9f6eace] | committer: Michael Niedermayer

avcodec/alacdsp: fix integer overflow in decorrelate_stereo()

Fixes: signed integer overflow: -16777216 * 131 cannot be represented in type 'int'
Fixes: 23835/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_ALAC_fuzzer-5669943160078336
Fixes: 41101/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_ALAC_fuzzer-4636330705944576

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 68457c1e85122ffcadb0c909070dd210095fd2cd)
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=50b56b539ec534d661cf1ffb2b4fbc8cb9f6eace
---

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

diff --git a/libavcodec/alacdsp.c b/libavcodec/alacdsp.c
index 9996eb4319..8718d1b6b1 100644
--- a/libavcodec/alacdsp.c
+++ b/libavcodec/alacdsp.c
@@ -34,7 +34,7 @@ static void decorrelate_stereo(int32_t *buffer[2], int nb_samples,
         a = buffer[0][i];
         b = buffer[1][i];
 
-        a -= (b * decorr_left_weight) >> decorr_shift;
+        a -= (int)(b * (unsigned)decorr_left_weight) >> decorr_shift;
         b += a;
 
         buffer[0][i] = b;