staging: xgifb: use display information in info not in var for panning

We must not use any information in the passed var besides xoffset,
yoffset and vmode as otherwise applications might abuse it.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: Aaro Koskinen <aaro.koskinen@iki.fi>
Cc: Arnaud Patard <apatard@mandriva.com>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>

drivers/staging/xgifb/XGI_main_26.c

@@ -1365,26 +1365,16 @@ static int XGIfb_do_set_var(struct fb_var_screeninfo *var, int isactive,
 }
 
 #ifdef XGIFB_PAN
-static int XGIfb_pan_var(struct fb_var_screeninfo *var)
+static int XGIfb_pan_var(struct fb_var_screeninfo *var, struct fb_info *info)
 {
 	unsigned int base;
 
 	/* printk("Inside pan_var"); */
 
-	if (var->xoffset > (var->xres_virtual - var->xres)) {
-		/* printk("Pan: xo: %d xv %d xr %d\n",
-			var->xoffset, var->xres_virtual, var->xres); */
-		return -EINVAL;
-	}
-	if (var->yoffset > (var->yres_virtual - var->yres)) {
-		/* printk("Pan: yo: %d yv %d yr %d\n",
-			var->yoffset, var->yres_virtual, var->yres); */
-		return -EINVAL;
-	}
-	base = var->yoffset * var->xres_virtual + var->xoffset;
+	base = var->yoffset * info->var.xres_virtual + var->xoffset;
 
 	/* calculate base bpp dep. */
-	switch (var->bits_per_pixel) {
+	switch (info->var.bits_per_pixel) {
 	case 16:
 		base >>= 1;
 		break;
@@ -1682,9 +1672,9 @@ static int XGIfb_pan_display(struct fb_var_screeninfo *var,
 
 	/* printk("\nInside pan_display:\n"); */
 
-	if (var->xoffset > (var->xres_virtual - var->xres))
+	if (var->xoffset > (info->var.xres_virtual - info->var.xres))
 		return -EINVAL;
-	if (var->yoffset > (var->yres_virtual - var->yres))
+	if (var->yoffset > (info->var.yres_virtual - info->var.yres))
 		return -EINVAL;
 
 	if (var->vmode & FB_VMODE_YWRAP) {
@@ -1697,7 +1687,7 @@ static int XGIfb_pan_display(struct fb_var_screeninfo *var,
 						> info->var.yres_virtual)
 			return -EINVAL;
 	}
-	err = XGIfb_pan_var(var);
+	err = XGIfb_pan_var(var, info);
 	if (err < 0)
 		return err;