[FFmpeg-cvslog] avcodec/wmalosslessdec: Fix integer overflows in revert_inter_ch_decorr()

[Michael Niedermayer]

ffmpeg | branch: release/2.8 | Michael Niedermayer <michael at niedermayer.cc> | Sun Apr 26 21:19:13 2020 +0200| [d8a1e0a79efcb8faf26350060bb57dcd449cd427] | committer: Michael Niedermayer

avcodec/wmalosslessdec: Fix integer overflows in revert_inter_ch_decorr()

Fixes: signed integer overflow: -717241856 + -1434459904 cannot be represented in type 'int'
Fixes: 21405/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_WMALOSSLESS_fuzzer-5677143666458624

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 e9a4c4fe9918220be492a4a9d74c2293fd706be3)
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=d8a1e0a79efcb8faf26350060bb57dcd449cd427
---

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

diff --git a/libavcodec/wmalosslessdec.c b/libavcodec/wmalosslessdec.c
index 0921c16fe5..b2622ddbd3 100644
--- a/libavcodec/wmalosslessdec.c
+++ b/libavcodec/wmalosslessdec.c
@@ -784,8 +784,8 @@ static void revert_inter_ch_decorr(WmallDecodeCtx *s, int tile_size)
     else if (s->is_channel_coded[0] || s->is_channel_coded[1]) {
         int icoef;
         for (icoef = 0; icoef < tile_size; icoef++) {
-            s->channel_residues[0][icoef] -= s->channel_residues[1][icoef] >> 1;
-            s->channel_residues[1][icoef] += s->channel_residues[0][icoef];
+            s->channel_residues[0][icoef] -= (unsigned)(s->channel_residues[1][icoef] >> 1);
+            s->channel_residues[1][icoef] += (unsigned) s->channel_residues[0][icoef];
         }
     }
 }