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authorEric Dumazet <edumazet@google.com>2012-06-08 06:25:00 +0000
committerBen Hutchings <ben@decadent.org.uk>2012-07-12 04:32:13 +0100
commit5b73845cd7629c3b944542999b8e69989a4dd70e (patch)
tree6861d6bcecbca187fc142cc46eba925d871d3fa3 /net/l2tp
parent43f06c88b9293b6bfb5724757c0c9e7d9e2b2103 (diff)
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l2tp: fix a race in l2tp_ip_sendmsg()
[ Upstream commit 4399a4df98a63e30fd16e9d0cecc46ea92269e8f ] Commit 081b1b1bb27f (l2tp: fix l2tp_ip_sendmsg() route handling) added a race, in case IP route cache is disabled. In this case, we should not do the dst_release(&rt->dst), since it'll free the dst immediately, instead of waiting a RCU grace period. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: James Chapman <jchapman@katalix.com> Cc: Denys Fedoryshchenko <denys@visp.net.lb> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Diffstat (limited to 'net/l2tp')
-rw-r--r--net/l2tp/l2tp_ip.c9
1 files changed, 6 insertions, 3 deletions
diff --git a/net/l2tp/l2tp_ip.c b/net/l2tp/l2tp_ip.c
index 2fbbe1f..6c7e609 100644
--- a/net/l2tp/l2tp_ip.c
+++ b/net/l2tp/l2tp_ip.c
@@ -515,10 +515,12 @@ static int l2tp_ip_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *m
sk->sk_bound_dev_if);
if (IS_ERR(rt))
goto no_route;
- if (connected)
+ if (connected) {
sk_setup_caps(sk, &rt->dst);
- else
- dst_release(&rt->dst); /* safe since we hold rcu_read_lock */
+ } else {
+ skb_dst_set(skb, &rt->dst);
+ goto xmit;
+ }
}
/* We dont need to clone dst here, it is guaranteed to not disappear.
@@ -526,6 +528,7 @@ static int l2tp_ip_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *m
*/
skb_dst_set_noref(skb, &rt->dst);
+xmit:
/* Queue the packet to IP for output */
rc = ip_queue_xmit(skb, &inet->cork.fl);
rcu_read_unlock();