[FFmpeg-cvslog] avcodec/diracdec: Fix overflow in DC computation

[Michael Niedermayer]

ffmpeg | branch: release/3.1 | Michael Niedermayer <michael at niedermayer.cc> | Sun Sep 10 01:32:50 2017 +0200| [10ae5fb2696103f46d74f069f7187883873002a6] | committer: Michael Niedermayer

avcodec/diracdec: Fix overflow in DC computation

Fixes: runtime error: signed integer overflow: 11896 + 2147483646 cannot be represented in type 'int'
Fixes: 3053/clusterfuzz-testcase-minimized-6355082062856192

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 b5995856a4236c27f231210bb08d70688e045192)
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=10ae5fb2696103f46d74f069f7187883873002a6
---

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

diff --git a/libavcodec/diracdec.c b/libavcodec/diracdec.c
index f92ff1b2ea..4f6de7af3d 100644
--- a/libavcodec/diracdec.c
+++ b/libavcodec/diracdec.c
@@ -1343,7 +1343,7 @@ static void decode_block_params(DiracContext *s, DiracArith arith[8], DiracBlock
     if (!block->ref) {
         pred_block_dc(block, stride, x, y);
         for (i = 0; i < 3; i++)
-            block->u.dc[i] += dirac_get_arith_int(arith+1+i, CTX_DC_F1, CTX_DC_DATA);
+            block->u.dc[i] += (unsigned)dirac_get_arith_int(arith+1+i, CTX_DC_F1, CTX_DC_DATA);
         return;
     }