diff mbox

[net,2/5] l2tp: hold socket before dropping lock in l2tp_ip{,6}_recv()

Message ID 7e2a79e6e3e72996a3c184e8259c993a7cbcc15b.1480360512.git.g.nault@alphalink.fr
State Changes Requested, archived
Delegated to: David Miller
Headers show

Commit Message

Guillaume Nault Nov. 28, 2016, 7:39 p.m. UTC 
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>
---
 net/l2tp/l2tp_ip.c  | 11 ++++++-----
 net/l2tp/l2tp_ip6.c | 11 ++++++-----
 2 files changed, 12 insertions(+), 10 deletions(-)
diff mbox

Patch

diff --git a/net/l2tp/l2tp_ip.c b/net/l2tp/l2tp_ip.c
index 1f57094..4d1c942 100644
--- a/net/l2tp/l2tp_ip.c
+++ b/net/l2tp/l2tp_ip.c
@@ -183,14 +183,15 @@  static int l2tp_ip_recv(struct sk_buff *skb)
 
 		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
--- a/net/l2tp/l2tp_ip6.c
+++ b/net/l2tp/l2tp_ip6.c
@@ -198,14 +198,15 @@  static int l2tp_ip6_recv(struct sk_buff *skb)
 		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;