net: fix a potential rcu_read_lock() imbalance in rt6_fill_node()

BugLink: http://bugs.launchpad.net/bugs/971808

[ Upstream commit 94f826b8076e2cb92242061e92f21b5baa3eccc2 ]

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 6 insertions, 2 deletions

diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index e70e902a5d0..8e600f827fe 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -2411,8 +2411,12 @@ static int rt6_fill_node(struct net *net,
 
         rcu_read_lock();
         n = dst_get_neighbour(&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)