[ 138/149] net: fix a potential rcu_read_lock() imbalance in rt6_fill_node()

[Greg KH]

3.2-stable review patch.  If anyone has any objections, please let me know.

------------------


From: Eric Dumazet <eric.dumazet@xxxxxxxxx>

[ 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@xxxxxxxxxxxxxxx>
Reported-by: Dave Jones <davej@xxxxxxxxxx>
Signed-off-by: Eric Dumazet <eric.dumazet@xxxxxxxxx>
Tested-by: Ben Greear <greearb@xxxxxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 net/ipv6/route.c |    8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -2446,8 +2446,12 @@ 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)


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