Message ID | 1339172700.6001.128.camel@edumazet-glaptop |
---|---|
State | Accepted, archived |
Delegated to: | David Miller |
Headers | show |
From: Eric Dumazet <eric.dumazet@gmail.com> Date: Fri, 08 Jun 2012 18:25:00 +0200 > From: Eric Dumazet <edumazet@google.com> > > 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> Working with a zero-ref'd object is always playing with fire even when we "know what we are doing" :-) Applied and queued up for -stable, thanks Eric. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/net/l2tp/l2tp_ip.c b/net/l2tp/l2tp_ip.c index 70614e7..61d8b75 100644 --- a/net/l2tp/l2tp_ip.c +++ b/net/l2tp/l2tp_ip.c @@ -464,10 +464,12 @@ 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. @@ -475,6 +477,7 @@ 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();