xscreensaver-6.07-0002-convert_ximage_to_rgba32-avoid-integer-overflow-on-l.patch

From b6aacc5eb73ef0d41bdff9cd62672d4dc7a62e0d Mon Sep 17 00:00:00 2001
From: XScreenSaver owners <xscreensaver-owner@fedoraproject.org>
Date: Fri, 1 Sep 2023 17:32:57 +0900
Subject: [PATCH 2/2] convert_ximage_to_rgba32: avoid integer overflow on left
 shift

gcc -fsanitize=undefined shows the following undefined behavior:

../../../hacks/glx/grab-ximage.c:213:21: runtime error: left shift of 255 by 24 places cannot be represented in type 'int'

This is because of integral promotion from unsigned char to int, not to unsigned int.

To avoid this error, cast to unsigned long type.
---
 hacks/glx/grab-ximage.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/hacks/glx/grab-ximage.c b/hacks/glx/grab-ximage.c
index defefda..9d3a2d6 100644
--- a/hacks/glx/grab-ximage.c
+++ b/hacks/glx/grab-ximage.c
@@ -207,10 +207,10 @@ convert_ximage_to_rgba32 (Screen *screen, XImage *image)
             sb = spread_map[2][sb];
           }
 
-        cp = ((sr << crpos) |
+        cp = ((((unsigned long)sr) << crpos) |
               (sg << cgpos) |
               (sb << cbpos) |
-              (0xFF << capos));
+              (0xFFUL << capos));
 
         XPutPixel (to, x, y, cp);
       }
-- 
2.41.0