[FFmpeg-cvslog] avcodec/ilbcdec: Fix integer overflow in construct_vector()

[Michael Niedermayer]

ffmpeg | branch: release/4.1 | Michael Niedermayer <michael at niedermayer.cc> | Tue Jan 15 00:02:25 2019 +0100| [62f5325ca30a3cc27c625bb468d65e2e4bfd7996] | committer: Michael Niedermayer

avcodec/ilbcdec: Fix integer overflow in construct_vector()

webrtc contains explicit code to ignore the undefined behavior (RTC_NO_SANITIZE / OverflowingAddS32S32ToS32())

Probably fixes: Integer overflow (unreproducable here)
Probably fixes: 12215/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_ILBC_fuzzer-5767142427852800

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 c95d0fb23917c35886f3b62daa05af20d2700a1e)
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=62f5325ca30a3cc27c625bb468d65e2e4bfd7996
---

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

diff --git a/libavcodec/ilbcdec.c b/libavcodec/ilbcdec.c
index 50012c0231..643547f4ab 100644
--- a/libavcodec/ilbcdec.c
+++ b/libavcodec/ilbcdec.c
@@ -745,7 +745,7 @@ static void construct_vector (
     for (j = 0; j < veclen; j++) {
         a32 = SPL_MUL_16_16(*gainPtr++, cbvec0[j]);
         a32 += SPL_MUL_16_16(*gainPtr++, cbvec1[j]);
-        a32 += SPL_MUL_16_16(*gainPtr, cbvec2[j]);
+        a32 += (unsigned)SPL_MUL_16_16(*gainPtr, cbvec2[j]);
         gainPtr -= 2;
         decvector[j] = (a32 + 8192) >> 14;
     }