From mboxrd@z Thu Jan 1 00:00:00 1970 From: Steffen Klassert Subject: [PATCH] ipv4: Fix route refcount on pmtu discovery Date: Tue, 22 Jan 2013 11:01:28 +0100 Message-ID: <20130122100128.GD9147@secunet.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Julian Anastasov , netdev@vger.kernel.org To: David Miller Return-path: Received: from a.mx.secunet.com ([195.81.216.161]:35048 "EHLO a.mx.secunet.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752898Ab3AVKBv (ORCPT ); Tue, 22 Jan 2013 05:01:51 -0500 Content-Disposition: inline Sender: netdev-owner@vger.kernel.org List-ID: git commit 9cb3a50c (ipv4: Invalidate the socket cached route on pmtu events if possible) introduced a refcount problem. We don't get a refcount on the route if we get it from__sk_dst_get(), but we need one if we want to reuse this route because __sk_dst_set() releases the refcount of the old route. This patch adds proper refcount handling for that case. We introduce a 'new' flag to indicate that we are going to use a new route and we release the old route only if we replace it by a new one. Reported-by: Julian Anastasov Signed-off-by: Steffen Klassert --- net/ipv4/route.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/net/ipv4/route.c b/net/ipv4/route.c index 132737a..a0fcc47 100644 --- a/net/ipv4/route.c +++ b/net/ipv4/route.c @@ -985,6 +985,7 @@ void ipv4_sk_update_pmtu(struct sk_buff *skb, struct sock *sk, u32 mtu) struct flowi4 fl4; struct rtable *rt; struct dst_entry *dst; + bool new = false; bh_lock_sock(sk); rt = (struct rtable *) __sk_dst_get(sk); @@ -1000,20 +1001,26 @@ void ipv4_sk_update_pmtu(struct sk_buff *skb, struct sock *sk, u32 mtu) rt = ip_route_output_flow(sock_net(sk), &fl4, sk); if (IS_ERR(rt)) goto out; + + new = true; } __ip_rt_update_pmtu((struct rtable *) rt->dst.path, &fl4, mtu); dst = dst_check(&rt->dst, 0); if (!dst) { + if (new) + dst_release(&rt->dst); + rt = ip_route_output_flow(sock_net(sk), &fl4, sk); if (IS_ERR(rt)) goto out; - dst = &rt->dst; + new = true; } - __sk_dst_set(sk, dst); + if (new) + __sk_dst_set(sk, &rt->dst); out: bh_unlock_sock(sk); -- 1.7.9.5