[gtk+/gtk-2-18] Avoid integer overflow in gdk_rectangle_intersect
- From: Alexander Larsson <alexl src gnome org>
- To: svn-commits-list gnome org
- Cc:
- Subject: [gtk+/gtk-2-18] Avoid integer overflow in gdk_rectangle_intersect
- Date: Fri, 22 Jan 2010 10:31:39 +0000 (UTC)
commit bb63c9537bb66ca3b7b856ccbe896a8f221f4cbb
Author: Alexander Larsson <alexl redhat com>
Date: Fri Jan 22 09:34:57 2010 +0100
Avoid integer overflow in gdk_rectangle_intersect
If e.g. the right edge of the leftmost rectangle is near MIN_INT, and
the left edge of the rightmost rectangle is large then subtracting these
can lead to an integer overflow, making the resultant "width" falsely
positive, thus returning a very wide result instead of the expected
no-intersection result.
We avoid the overflow by not doing the subtraction unless we know the
result will be positive. There are still risks for overflow if x + width
or y + width is larger than MAXINT, but we won't ever overflow for valid
rects now.
This may fix #607687
(cherry picked from commit 3c618f2f1f2181cb86226515e894f235f35b5fef)
gdk/gdkrectangle.c | 12 ++++++------
1 files changed, 6 insertions(+), 6 deletions(-)
---
diff --git a/gdk/gdkrectangle.c b/gdk/gdkrectangle.c
index 17d7e00..1f06f7d 100644
--- a/gdk/gdkrectangle.c
+++ b/gdk/gdkrectangle.c
@@ -79,7 +79,7 @@ gdk_rectangle_intersect (const GdkRectangle *src1,
GdkRectangle *dest)
{
gint dest_x, dest_y;
- gint dest_w, dest_h;
+ gint dest_x2, dest_y2;
gint return_val;
g_return_val_if_fail (src1 != NULL, FALSE);
@@ -89,17 +89,17 @@ gdk_rectangle_intersect (const GdkRectangle *src1,
dest_x = MAX (src1->x, src2->x);
dest_y = MAX (src1->y, src2->y);
- dest_w = MIN (src1->x + src1->width, src2->x + src2->width) - dest_x;
- dest_h = MIN (src1->y + src1->height, src2->y + src2->height) - dest_y;
+ dest_x2 = MIN (src1->x + src1->width, src2->x + src2->width);
+ dest_y2 = MIN (src1->y + src1->height, src2->y + src2->height);
- if (dest_w > 0 && dest_h > 0)
+ if (dest_x2 > dest_x && dest_y2 > dest_y)
{
if (dest)
{
dest->x = dest_x;
dest->y = dest_y;
- dest->width = dest_w;
- dest->height = dest_h;
+ dest->width = dest_x2 - dest_x;
+ dest->height = dest_y2 - dest_y;
}
return_val = TRUE;
}
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