[FFmpeg-cvslog] avcodec/diracdec: Use int64 in global mv to prevent overflow

[Michael Niedermayer]

ffmpeg | branch: release/2.8 | Michael Niedermayer <michael at niedermayer.cc> | Sat Feb 17 23:54:44 2018 +0100| [299b981382725c1befb56c8f324ce067783220d6] | committer: Michael Niedermayer

avcodec/diracdec: Use int64 in global mv to prevent overflow

Fixes: runtime error: signed integer overflow: 361 * -6295541 cannot be represented in type 'int'
Fixes: 5911/clusterfuzz-testcase-minimized-6450382197751808

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 cbcbefdc3b4cbc917d2f8b2dd216fb12121a838b)
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=299b981382725c1befb56c8f324ce067783220d6
---

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

diff --git a/libavcodec/diracdec.c b/libavcodec/diracdec.c
index 7c7a31e830..fb54312c49 100644
--- a/libavcodec/diracdec.c
+++ b/libavcodec/diracdec.c
@@ -1186,8 +1186,8 @@ static void global_mv(DiracContext *s, DiracBlock *block, int x, int y, int ref)
     int *c      = s->globalmc[ref].perspective;
 
     int m       = (1<<ep) - (c[0]*x + c[1]*y);
-    int mx      = m * ((A[0][0] * x + A[0][1]*y) + (1<<ez) * b[0]);
-    int my      = m * ((A[1][0] * x + A[1][1]*y) + (1<<ez) * b[1]);
+    int64_t mx  = m * (int64_t)((A[0][0] * x + A[0][1]*y) + (1<<ez) * b[0]);
+    int64_t my  = m * (int64_t)((A[1][0] * x + A[1][1]*y) + (1<<ez) * b[1]);
 
     block->u.mv[ref][0] = (mx + (1<<(ez+ep))) >> (ez+ep);
     block->u.mv[ref][1] = (my + (1<<(ez+ep))) >> (ez+ep);