[FFmpeg-cvslog] avcodec/mjpegdec: Fix integer overflow in ljpeg_decode_rgb_scan()

[Michael Niedermayer]

ffmpeg | branch: release/4.0 | Michael Niedermayer <michael at niedermayer.cc> | Tue Jun  5 02:17:24 2018 +0200| [4b12afccb2c8f507bf30ff9b4ef62f051f2571c8] | committer: Michael Niedermayer

avcodec/mjpegdec: Fix integer overflow in ljpeg_decode_rgb_scan()

Fixes: signed integer overflow: 32768 + 2147450880 cannot be represented in type 'int'
Fixes: 7885/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_THP_fuzzer-5298834394578944

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 936f4a2c2e14ec753e8835f2e820b4cd9aec9a56)
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=4b12afccb2c8f507bf30ff9b4ef62f051f2571c8
---

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

diff --git a/libavcodec/mjpegdec.c b/libavcodec/mjpegdec.c
index 22ca69f841..d1dca84d36 100644
--- a/libavcodec/mjpegdec.c
+++ b/libavcodec/mjpegdec.c
@@ -1078,7 +1078,7 @@ static int ljpeg_decode_rgb_scan(MJpegDecodeContext *s, int nb_components, int p
                     return -1;
 
                 left[i] = buffer[mb_x][i] =
-                    mask & (pred + (dc * (1 << point_transform)));
+                    mask & (pred + (unsigned)(dc * (1 << point_transform)));
             }
 
             if (s->restart_interval && !--s->restart_count) {