[FFmpeg-cvslog] avcodec/movtextdec: Fix shift overflows in mov_text_init()

[Michael Niedermayer]

ffmpeg | branch: release/4.3 | Michael Niedermayer <michael at niedermayer.cc> | Fri Jun  5 18:22:51 2020 +0200| [611fc7244a1a93b4d0fd652d13a09c52f2dc19f3] | committer: Michael Niedermayer

avcodec/movtextdec: Fix shift overflows in mov_text_init()

Fixes: left shift of 243 by 24 places cannot be represented in type 'int'
Fixes: 22716/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_MOVTEXT_fuzzer-5704263425851392

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 d7a2311a2c5be1e861c3df618d295e7eced8e84b)
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=611fc7244a1a93b4d0fd652d13a09c52f2dc19f3
---

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

diff --git a/libavcodec/movtextdec.c b/libavcodec/movtextdec.c
index 4b4da5e0d9..4a21dbf36d 100644
--- a/libavcodec/movtextdec.c
+++ b/libavcodec/movtextdec.c
@@ -492,10 +492,10 @@ static int mov_text_init(AVCodecContext *avctx) {
         return ff_ass_subtitle_header_full(avctx,
                     m->frame_width, m->frame_height,
                     m->d.font, m->d.fontsize,
-                    (255 - m->d.alpha) << 24 | RGB_TO_BGR(m->d.color),
-                    (255 - m->d.alpha) << 24 | RGB_TO_BGR(m->d.color),
-                    (255 - m->d.back_alpha) << 24 | RGB_TO_BGR(m->d.back_color),
-                    (255 - m->d.back_alpha) << 24 | RGB_TO_BGR(m->d.back_color),
+                    (255U - m->d.alpha) << 24 | RGB_TO_BGR(m->d.color),
+                    (255U - m->d.alpha) << 24 | RGB_TO_BGR(m->d.color),
+                    (255U - m->d.back_alpha) << 24 | RGB_TO_BGR(m->d.back_color),
+                    (255U - m->d.back_alpha) << 24 | RGB_TO_BGR(m->d.back_color),
                     m->d.bold, m->d.italic, m->d.underline,
                     ASS_DEFAULT_BORDERSTYLE, m->d.alignment);
     } else