l2tp: ensure sk->dst is still valid

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->check callback finds that the bundle is no longer valid).

Cc: James Chapman <jchapman@katalix.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
Acked-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/l2tp/l2tp_core.c b/net/l2tp/l2tp_core.c
index cf0f308abf5e7324aa05a40cfffd4eee166b0d51..89ff8c67943e8af26efe1bac80b306e297921ebd 100644 (file)
--- 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;