l2tp: drop ->flags from struct pppol2tp_session

This field is not used.

Keep validating user input in PPPIOCSFLAGS. Even though we discard the
value, it would look wrong to succeed if an invalid address was passed
from userspace.
Signed-off-by: NGuillaume Nault <g.nault@alphalink.fr>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/l2tp/l2tp_ppp.c

@@ -127,8 +127,6 @@ struct pppol2tp_session {
 						 * PPPoX socket */
 	struct sock		*__sk;		/* Copy of .sk, for cleanup */
 	struct rcu_head		rcu;		/* For asynchronous release */
-	int			flags;		/* accessed by PPPIOCGFLAGS.
-						 * Unused. */
 };
 
 static int pppol2tp_xmit(struct ppp_channel *chan, struct sk_buff *skb);
@@ -1057,7 +1055,6 @@ static int pppol2tp_session_ioctl(struct l2tp_session *session,
 	int err = 0;
 	struct sock *sk;
 	int val = (int) arg;
-	struct pppol2tp_session *ps = l2tp_session_priv(session);
 	struct l2tp_tunnel *tunnel = session->tunnel;
 	struct pppol2tp_ioc_stats stats;
 
@@ -1134,21 +1131,15 @@ static int pppol2tp_session_ioctl(struct l2tp_session *session,
 
 	case PPPIOCGFLAGS:
 		err = -EFAULT;
-		if (put_user(ps->flags, (int __user *) arg))
+		if (put_user(0, (int __user *)arg))
 			break;
-
-		l2tp_info(session, L2TP_MSG_CONTROL, "%s: get flags=%d\n",
-			  session->name, ps->flags);
 		err = 0;
 		break;
 
 	case PPPIOCSFLAGS:
 		err = -EFAULT;
-		if (get_user(val, (int __user *) arg))
+		if (get_user(val, (int __user *)arg))
 			break;
-		ps->flags = val;
-		l2tp_info(session, L2TP_MSG_CONTROL, "%s: set flags=%d\n",
-			  session->name, ps->flags);
 		err = 0;
 		break;