l2tp: ensure sk->dst is still valid

Florian Westphal · davem330 · commit 71b1391a4128 · 2011-11-26T15:57:36.000-05:00
When using l2tp over ipsec, the tunnel will hang when rekeying
occurs. Reason is that the transformer bundle attached to the dst entry
is now in STATE_DEAD and thus xfrm_output_one() drops all packets
(XfrmOutStateExpired increases).

Fix this by calling __sk_dst_check (which drops the stale dst
if xfrm dst-&gt;check callback finds that the bundle is no longer valid).

Cc: James Chapman &lt;jchapman@katalix.com&gt;
Signed-off-by: Florian Westphal &lt;fw@strlen.de&gt;
Acked-by: Eric Dumazet &lt;eric.dumazet@gmail.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
diff --git a/net/l2tp/l2tp_core.c b/net/l2tp/l2tp_core.c
@@ -1072,7 +1072,7 @@ int l2tp_xmit_skb(struct l2tp_session *session, struct sk_buff *skb, int hdr_len
 
 	/* Get routing info from the tunnel socket */
 	skb_dst_drop(skb);
-	skb_dst_set(skb, dst_clone(__sk_dst_get(sk)));
+	skb_dst_set(skb, dst_clone(__sk_dst_check(sk, 0)));
 
 	inet = inet_sk(sk);
 	fl = &inet->cork.fl;
