l2tp: hold socket before dropping lock in l2tp_ip{, 6}_recv()

Socket must be held while under the protection of the l2tp lock; there
is no guarantee that sk remains valid after the read_unlock_bh() call.

Same issue for l2tp_ip and l2tp_ip6.

Signed-off-by: Guillaume Nault <g.nault@alphalink.fr>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/l2tp/l2tp_ip.c b/net/l2tp/l2tp_ip.c
index 1f57094..4d1c942 100644 (file)
--- a/net/l2tp/l2tp_ip.c
+++ b/net/l2tp/l2tp_ip.c
@@ -183,14 +183,15 @@ pass_up:
 
                read_lock_bh(&l2tp_ip_lock);
                sk = __l2tp_ip_bind_lookup(net, iph->daddr, 0, tunnel_id);
+               if (!sk) {
+                       read_unlock_bh(&l2tp_ip_lock);
+                       goto discard;
+               }
+
+               sock_hold(sk);
                read_unlock_bh(&l2tp_ip_lock);
        }
 
-       if (sk == NULL)
-               goto discard;
-
-       sock_hold(sk);
-
        if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb))
                goto discard_put;
 

diff --git a/net/l2tp/l2tp_ip6.c b/net/l2tp/l2tp_ip6.c
index af9abff..e3fc778 100644 (file)
--- a/net/l2tp/l2tp_ip6.c
+++ b/net/l2tp/l2tp_ip6.c
@@ -198,14 +198,15 @@ pass_up:
                read_lock_bh(&l2tp_ip6_lock);
                sk = __l2tp_ip6_bind_lookup(net, &iph->daddr,
                                            0, tunnel_id);
+               if (!sk) {
+                       read_unlock_bh(&l2tp_ip6_lock);
+                       goto discard;
+               }
+
+               sock_hold(sk);
                read_unlock_bh(&l2tp_ip6_lock);
        }
 
-       if (sk == NULL)
-               goto discard;
-
-       sock_hold(sk);
-
        if (!xfrm6_policy_check(sk, XFRM_POLICY_IN, skb))
                goto discard_put;