[FFmpeg-cvslog] avcodec/snowenc: sign extend a variable before shifting

[James Almer]

ffmpeg | branch: master | James Almer <jamrial at gmail.com> | Tue Aug 13 22:07:17 2024 -0300| [9880fea9306cd86c0907e7ac40716fa233abba14] | committer: James Almer

avcodec/snowenc: sign extend a variable before shifting

Fixes "libavcodec/snowenc.c:718:27: runtime error: left shift of 8509032 by 8 places cannot be represented in type 'int'"
as seen in fate-vsynth2-snow-hpel under ubsan.

Signed-off-by: James Almer <jamrial at gmail.com>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=9880fea9306cd86c0907e7ac40716fa233abba14
---

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

diff --git a/libavcodec/snowenc.c b/libavcodec/snowenc.c
index 0b87d751b8..eac81d0d7c 100644
--- a/libavcodec/snowenc.c
+++ b/libavcodec/snowenc.c
@@ -715,7 +715,7 @@ static int get_dc(SnowEncContext *enc, int mb_x, int mb_y, int plane_index)
     }
     *b= backup;
 
-    return av_clip_uint8( ROUNDED_DIV(ab<<LOG2_OBMC_MAX, aa) ); //FIXME we should not need clipping
+    return av_clip_uint8( ROUNDED_DIV((int64_t)ab<<LOG2_OBMC_MAX, aa) ); //FIXME we should not need clipping
 }
 
 static inline int get_block_bits(SnowContext *s, int x, int y, int w){