Commit b44108db authored Jan 22, 2013 by Steffen Klassert Committed by David S. Miller Jan 22, 2013

ipv4: Fix route refcount on pmtu discovery



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 <ja@ssi.bg>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent 0c8729c9

net/ipv4/route.c

+9 −2

Original line number	Diff line number	Diff line
		@@ -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);

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