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50 lines
1.7 KiB
50 lines
1.7 KiB
12 months ago
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From 1e20010cd70edd4c26bbc6ce48c57bf36b064aeb Mon Sep 17 00:00:00 2001
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From: XScreenSaver owners <xscreensaver-owner@fedoraproject.org>
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Date: Fri, 1 Sep 2023 17:30:50 +0900
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Subject: [PATCH 1/2] make_ximage: avoid integer overflow on left shift
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gcc -fsanitize=undefined shows the following undefined behavior:
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../../hacks/ximage-loader.c:176:29: runtime error: left shift of 255 by 24 places cannot be represented in type 'int'
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../../hacks/ximage-loader.c:169:29: runtime error: left shift of 255 by 24 places cannot be represented in type 'int'
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This is because of integral promotion from guchar to int, not to unsigned int.
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To avoid this error, cast to unsigned long type.
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---
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hacks/ximage-loader.c | 4 ++--
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1 file changed, 2 insertions(+), 2 deletions(-)
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diff --git a/hacks/ximage-loader.c b/hacks/ximage-loader.c
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index a3f6eb0..152ad9f 100644
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--- a/hacks/ximage-loader.c
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+++ b/hacks/ximage-loader.c
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@@ -159,21 +159,21 @@ make_ximage (Display *dpy, Visual *visual, const char *filename,
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unsigned long rgba = 0;
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switch (chan) {
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case 1:
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- rgba = ((0xFF << 24) |
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+ rgba = ((0xFFUL << 24) |
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(*i << 16) |
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(*i << 8) |
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*i);
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i++;
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break;
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case 3:
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- rgba = ((0xFF << 24) |
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+ rgba = ((0xFFUL << 24) |
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(i[2] << 16) |
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(i[1] << 8) |
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i[0]);
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i += 3;
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break;
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case 4:
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- rgba = ((i[3] << 24) |
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+ rgba = ((((unsigned long)i[3]) << 24) |
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(i[2] << 16) |
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(i[1] << 8) |
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i[0]);
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--
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2.41.0
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