net/dccp: 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>
Acked-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/dccp/proto.c

@@ -473,14 +473,9 @@ static int dccp_setsockopt_ccid(struct sock *sk, int type,
 	if (optlen < 1 || optlen > DCCP_FEAT_MAX_SP_VALS)
 		return -EINVAL;
 
-	val = kmalloc(optlen, GFP_KERNEL);
-	if (val == NULL)
-		return -ENOMEM;
-
-	if (copy_from_user(val, optval, optlen)) {
-		kfree(val);
-		return -EFAULT;
-	}
+	val = memdup_user(optval, optlen);
+	if (IS_ERR(val))
+		return PTR_ERR(val);
 
 	lock_sock(sk);
 	if (type == DCCP_SOCKOPT_TX_CCID || type == DCCP_SOCKOPT_CCID)