USB: gadget: 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: Greg Kroah-Hartman <gregkh@suse.de>

drivers/usb/gadget/inode.c

@@ -1867,13 +1867,9 @@ dev_config (struct file *fd, const char __user *buf, size_t len, loff_t *ptr)
 	buf += 4;
 	length -= 4;
 
-	kbuf = kmalloc (length, GFP_KERNEL);
-	if (!kbuf)
-		return -ENOMEM;
-	if (copy_from_user (kbuf, buf, length)) {
-		kfree (kbuf);
-		return -EFAULT;
-	}
+	kbuf = memdup_user(buf, length);
+	if (IS_ERR(kbuf))
+		return PTR_ERR(kbuf);
 
 	spin_lock_irq (&dev->lock);
 	value = -EINVAL;