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>

1 files changed, 15 insertions, 4 deletions

diff --git a/net/l2tp/l2tp_ip.c b/net/l2tp/l2tp_ip.c
index 81899600abe2..bd0cc0b8f32f 100644
--- 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,