| From | Greg Kroah-Hartman <> | Subject | [ 48/61] ipv4: Fix route refcount on pmtu discovery | Date | Tue, 12 Feb 2013 12:35:08 -0800 |
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3.7-stable review patch. If anyone has any objections, please let me know.
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From: Steffen Klassert <steffen.klassert@secunet.com>
[ Upstream commit b44108dbdbaa07c609bb5755e8dd6c2035236251 ]
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> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> --- net/ipv4/route.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-)
--- a/net/ipv4/route.c +++ b/net/ipv4/route.c @@ -985,6 +985,7 @@ void ipv4_sk_update_pmtu(struct sk_buff 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 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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