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: Antonino Daplas Signed-off-by: Andrew Morton --- drivers/video/vga16fb.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff -puN drivers/video/vga16fb.c~vga16fb-test-virtual-screen-range-before-subtraction-on-unsigned drivers/video/vga16fb.c --- a/drivers/video/vga16fb.c~vga16fb-test-virtual-screen-range-before-subtraction-on-unsigned +++ a/drivers/video/vga16fb.c @@ -1087,12 +1087,15 @@ static void vga16fb_copyarea(struct fb_i width = x2 - dx; height = y2 - dy; + if (sx + dx < old_dx || sy + dy < old_dy) + return; + /* update sx1,sy1 */ sx += (dx - old_dx); sy += (dy - old_dy); /* the source must be completely inside the virtual screen */ - if (sx < 0 || sy < 0 || (sx + width) > vxres || (sy + height) > vyres) + if (sx + width > vxres || sy + height > vyres) return; switch (info->fix.type) { _