[FFmpeg-cvslog] avcodec/truemotion2: Fix integer overflow in TM2_RECALC_BLOCK()

[Michael Niedermayer]

ffmpeg | branch: release/2.8 | Michael Niedermayer <michael at niedermayer.cc> | Sat Jan 20 04:10:50 2018 +0100| [25f7121c7b98b3d188e4896d5bdd83ac7da903fe] | committer: Michael Niedermayer

avcodec/truemotion2: Fix integer overflow in TM2_RECALC_BLOCK()

Fixes: signed integer overflow: 1477974040 - -1877995504 cannot be represented in type 'int'
Fixes: 4861/clusterfuzz-testcase-minimized-4570316383715328

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 56a53340ed4cc55898e49c07081311ebb2816630)
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=25f7121c7b98b3d188e4896d5bdd83ac7da903fe
---

 libavcodec/truemotion2.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/libavcodec/truemotion2.c b/libavcodec/truemotion2.c
index 3f98c860b5..b77df57baa 100644
--- a/libavcodec/truemotion2.c
+++ b/libavcodec/truemotion2.c
@@ -433,8 +433,8 @@ static inline int GET_TOK(TM2Context *ctx,int type)
 
 /* recalculate last and delta values for next blocks */
 #define TM2_RECALC_BLOCK(CHR, stride, last, CD) {\
-    CD[0] = CHR[1] - last[1];\
-    CD[1] = (int)CHR[stride + 1] - (int)CHR[1];\
+    CD[0] = (unsigned)CHR[         1] - (unsigned)last[1];\
+    CD[1] = (unsigned)CHR[stride + 1] - (unsigned) CHR[1];\
     last[0] = (int)CHR[stride + 0];\
     last[1] = (int)CHR[stride + 1];}