drivers/char/vt.c: use memdup_user

Use memdup_user when user data is immediately copied into the
allocated region.

The semantic patch that makes this change is as follows:
(http://coccinelle.lip6.fr/)

// <smpl>
@@
expression from,to,size,flag;
position p;
identifier l1,l2;
@@

-  to = \(kmalloc@p\|kzalloc@p\)(size,flag);
+  to = memdup_user(from,size);
   if (
-      to==NULL
+      IS_ERR(to)
                 || ...) {
   <+... when != goto l1;
-  -ENOMEM
+  PTR_ERR(to)
   ...+>
   }
-  if (copy_from_user(to, from, size) != 0) {
-    <+... when != goto l2;
-    -EFAULT
-    ...+>
-  }
// </smpl>

Signed-off-by: Julia Lawall <julia@diku.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/char/vt.c

@@ -3967,13 +3967,9 @@ static int con_font_set(struct vc_data *vc, struct console_font_op *op)
 	font.charcount = op->charcount;
 	font.height = op->height;
 	font.width = op->width;
-	font.data = kmalloc(size, GFP_KERNEL);
-	if (!font.data)
-		return -ENOMEM;
-	if (copy_from_user(font.data, op->data, size)) {
-		kfree(font.data);
-		return -EFAULT;
-	}
+	font.data = memdup_user(op->data, size);
+	if (IS_ERR(font.data))
+		return PTR_ERR(font.data);
 	acquire_console_sem();
 	if (vc->vc_sw->con_font_set)
 		rc = vc->vc_sw->con_font_set(vc, &font, op->flags);