From 1c0face9d4024bf942096297937759bdf0e1aeac Mon Sep 17 00:00:00 2001
From: Roel Kluin <12o3l@tiscali.nl>
Date: Wed, 23 Jul 2008 21:31:18 -0700
Subject: [PATCH] atafb: test virtual screen range before subtraction on
 unsigned

dx and dy are u32's, so the test should occur before the subtraction

Signed-off-by: Roel Kluin <12o3l@tiscali.nl>
Cc: Tim Schmielau <tim@physik3.uni-rostock.de>
Cc: Krzysztof Helt <krzysztof.h1@wp.pl>
Cc: Antonino Daplas <adaplas@pol.net>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
 drivers/video/atafb.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/video/atafb.c b/drivers/video/atafb.c
index fa55d356b535..77eb8b34fbfa 100644
--- a/drivers/video/atafb.c
+++ b/drivers/video/atafb.c
@@ -2593,13 +2593,16 @@ static void atafb_copyarea(struct fb_info *info, const struct fb_copyarea *area)
 	width = x2 - dx;
 	height = y2 - dy;
 
+	if (area->sx + dx < area->dx || area->sy + dy < area->dy)
+		return;
+
 	/* update sx,sy */
 	sx = area->sx + (dx - area->dx);
 	sy = area->sy + (dy - area->dy);
 
 	/* the source must be completely inside the virtual screen */
-	if (sx < 0 || sy < 0 || (sx + width) > info->var.xres_virtual ||
-	    (sy + height) > info->var.yres_virtual)
+	if (sx + width > info->var.xres_virtual ||
+			sy + height > info->var.yres_virtual)
 		return;
 
 	if (dy > sy || (dy == sy && dx > sx)) {