l2tp: fix a race in l2tp_ip_sendmsg()
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>
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 @@
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 @@
*/
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();
