[PATCH] ip: fix error handling in ip_finish_output2()

[Vasily Kulikov <segoon@openwall.com>]

__neigh_create() returns either a pointer to struct neighbour or PTR_ERR().
But the caller expects it to return either a pointer or NULL.  Replace
the NULL check with IS_ERR() check.

The bug was introduced in a263b3093641fb1ec377582c90986a7fd0625184.

Signed-off-by: Vasily Kulikov <segoon@openwall.com>
---
 Compile tested only.

 net/ipv4/ip_output.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
index ba39a52..76dde25 100644
--- a/net/ipv4/ip_output.c
+++ b/net/ipv4/ip_output.c
@@ -197,7 +197,7 @@ static inline int ip_finish_output2(struct sk_buff *skb)
 	neigh = __ipv4_neigh_lookup_noref(dev, nexthop);
 	if (unlikely(!neigh))
 		neigh = __neigh_create(&arp_tbl, &nexthop, dev, false);
-	if (neigh) {
+	if (!IS_ERR(neigh)) {
 		int res = dst_neigh_output(dst, neigh, skb);
 
 		rcu_read_unlock_bh();
-- 
1.7.0.4