From: Stefano Brivio <sbrivio@redhat.com>
Date: Thu, 31 Aug 2017 18:11:41 +0200
Subject: ipv4: Don't override return code from ip_route_input_noref()
Patch-mainline: v4.14-rc1
Git-commit: 64327fc811268d4a24de03dac242ea29de6be75f
References: bsc#1061739

After ip_route_input() calls ip_route_input_noref(), another
check on skb_dst() is done, but if this fails, we shouldn't
override the return code from ip_route_input_noref(), as it
could have been more specific (i.e. -EHOSTUNREACH).

This also saves one call to skb_dst_force_safe() and one to
skb_dst() in case the ip_route_input_noref() check fails.

Reported-by: Sabrina Dubroca <sdubroca@redhat.com>
Fixes: 9df16efadd2a ("ipv4: call dst_hold_safe() properly")
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Acked-by: Wei Wang <weiwan@google.com>
Acked-by: Sabrina Dubroca <sd@queasysnail.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Michal Kubecek <mkubecek@suse.cz>

---
 include/net/route.h | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/include/net/route.h b/include/net/route.h
index 4795f5688fca..374a3140a61f 100644
--- a/include/net/route.h
+++ b/include/net/route.h
@@ -183,10 +183,11 @@ static inline int ip_route_input(struct sk_buff *skb, __be32 dst, __be32 src,
 
 	rcu_read_lock();
 	err = ip_route_input_noref(skb, dst, src, tos, devin);
-	if (!err)
+	if (!err) {
 		skb_dst_force_safe(skb);
-	if (!skb_dst(skb))
-		err = -EINVAL;
+		if (!skb_dst(skb))
+			err = -EINVAL;
+	}
 	rcu_read_unlock();
 
 	return err;
-- 
2.14.2