net: fix a potential rcu_read_lock() imbalance in rt6_fill_node()
Eric Dumazet [Tue, 27 Mar 2012 09:53:52 +0000 (09:53 +0000)]
Commit f2c31e32b378 (net: fix NULL dereferences in check_peer_redir() )
added a regression in rt6_fill_node(), leading to rcu_read_lock()
imbalance.

Thats because NLA_PUT() can make a jump to nla_put_failure label.

Fix this by using nla_put()

Many thanks to Ben Greear for his help

Reported-by: Ben Greear <greearb@candelatech.com>
Reported-by: Dave Jones <davej@redhat.com>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Tested-by: Ben Greear <greearb@candelatech.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv6/route.c

index 24c456e..496b627 100644 (file)
@@ -2474,8 +2474,12 @@ static int rt6_fill_node(struct net *net,
 
        rcu_read_lock();
        n = dst_get_neighbour_noref(&rt->dst);
-       if (n)
-               NLA_PUT(skb, RTA_GATEWAY, 16, &n->primary_key);
+       if (n) {
+               if (nla_put(skb, RTA_GATEWAY, 16, &n->primary_key) < 0) {
+                       rcu_read_unlock();
+                       goto nla_put_failure;
+               }
+       }
        rcu_read_unlock();
 
        if (rt->dst.dev)