[FFmpeg-cvslog] avcodec/truemotion2: Fix several integer overflows in tm2_motion_block()

[Michael Niedermayer]

ffmpeg | branch: release/4.2 | Michael Niedermayer <michael at niedermayer.cc> | Mon Jul  8 23:00:09 2019 +0200| [a2c8df28c9c6d63d2ce7fb04e9aa677da07246ea] | committer: Michael Niedermayer

avcodec/truemotion2: Fix several integer overflows in tm2_motion_block()

Fixes: 15524/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_TRUEMOTION2_fuzzer-5173148372172800
Fixes: signed integer overflow: 13701388 - -2134868270 cannot be represented in type 'int'

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 9a353ea8766206bd302f3f12ca1d226237542908)
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=a2c8df28c9c6d63d2ce7fb04e9aa677da07246ea
---

 libavcodec/truemotion2.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/libavcodec/truemotion2.c b/libavcodec/truemotion2.c
index a86dd16e0f..5d6dfc24c3 100644
--- a/libavcodec/truemotion2.c
+++ b/libavcodec/truemotion2.c
@@ -764,10 +764,10 @@ static inline void tm2_motion_block(TM2Context *ctx, AVFrame *pic, int bx, int b
     }
     /* calculate deltas */
     Y -= Ystride * 4;
-    ctx->D[0] = Y[3] - last[3];
-    ctx->D[1] = Y[3 + Ystride] - Y[3];
-    ctx->D[2] = Y[3 + Ystride * 2] - Y[3 + Ystride];
-    ctx->D[3] = Y[3 + Ystride * 3] - Y[3 + Ystride * 2];
+    ctx->D[0] = (unsigned)Y[3] - last[3];
+    ctx->D[1] = (unsigned)Y[3 + Ystride] - Y[3];
+    ctx->D[2] = (unsigned)Y[3 + Ystride * 2] - Y[3 + Ystride];
+    ctx->D[3] = (unsigned)Y[3 + Ystride * 3] - Y[3 + Ystride * 2];
     for (i = 0; i < 4; i++)
         last[i] = Y[i + Ystride * 3];
 }