l2tp: Fix locking in l2tp_ip.c

Both l2tp_ip_connect() and l2tp_ip_sendmsg() must take the socket
lock.  They both modify socket state non-atomically, and in particular
l2tp_ip_sendmsg() increments socket private counters without using
atomic operations.
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/l2tp/l2tp_ip.c b/net/l2tp/l2tp_ip.c
index 8189960..bd0cc0b 100644 (file)
--- a/net/l2tp/l2tp_ip.c
+++ b/net/l2tp/l2tp_ip.c
@@ -311,6 +311,8 @@ static int l2tp_ip_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len
        if (lsa->l2tp_family != AF_INET)
                goto out;
 
+       lock_sock(sk);
+
        sk_dst_reset(sk);
 
        oif = sk->sk_bound_dev_if;
@@ -356,6 +358,7 @@ static int l2tp_ip_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len
 
        rc = 0;
 out:
+       release_sock(sk);
        return rc;
 }
 
@@ -420,18 +423,23 @@ static int l2tp_ip_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *m
        int connected = 0;
        __be32 daddr;
 
+       lock_sock(sk);
+
+       rc = -ENOTCONN;
        if (sock_flag(sk, SOCK_DEAD))
-               return -ENOTCONN;
+               goto out;
 
        /* Get and verify the address. */
        if (msg->msg_name) {
                struct sockaddr_l2tpip *lip = (struct sockaddr_l2tpip *) msg->msg_name;
+               rc = -EINVAL;
                if (msg->msg_namelen < sizeof(*lip))
-                       return -EINVAL;
+                       goto out;
 
                if (lip->l2tp_family != AF_INET) {
+                       rc = -EAFNOSUPPORT;
                        if (lip->l2tp_family != AF_UNSPEC)
-                               return -EAFNOSUPPORT;
+                               goto out;
                }
 
                daddr = lip->l2tp_addr.s_addr;
@@ -510,12 +518,15 @@ error:
                lsa->tx_errors++;
        }
 
+out:
+       release_sock(sk);
        return rc;
 
 no_route:
        IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTNOROUTES);
        kfree_skb(skb);
-       return -EHOSTUNREACH;
+       rc = -EHOSTUNREACH;
+       goto out;
 }
 
 static int l2tp_ip_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,