From: Roel Kluin <12o3l@tiscali.nl> 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 Cc: Krzysztof Helt Cc: Antonino Daplas Cc: Geert Uytterhoeven Signed-off-by: Andrew Morton --- drivers/video/atafb.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff -puN drivers/video/atafb.c~atafb-test-virtual-screen-range-before-subtraction-on-unsigned drivers/video/atafb.c --- a/drivers/video/atafb.c~atafb-test-virtual-screen-range-before-subtraction-on-unsigned +++ a/drivers/video/atafb.c @@ -2593,13 +2593,16 @@ static void atafb_copyarea(struct fb_inf 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)) { _