Subject: [PATCH net-next] ipv4: Handle RTA_GATEWAY set to 0

From: David Ahern <[email-masked]>
Date: Wed, 10 Apr 2019 10:05:51 -0700

From: David Ahern <[email-masked]>

Govindarajulu reported a regression with Network Manager which sends an
RTA_GATEWAY attribute with the address set to 0. Fixup the handling of
RTA_GATEWAY to only set fc_gw_family if the gateway address is actually
set.

Fixes: f35b794b3b405 ("ipv4: Prepare fib_config for IPv6 gateway")
Reported-by: Govindarajulu Varadarajan <[email-masked]>
Signed-off-by: David Ahern <[email-masked]>
---
 net/ipv4/fib_frontend.c  | 3 ++-
 net/ipv4/fib_semantics.c | 3 ++-
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/net/ipv4/fib_frontend.c b/net/ipv4/fib_frontend.c
index 310060e67790..d4b63f94f7be 100644
--- a/net/ipv4/fib_frontend.c
+++ b/net/ipv4/fib_frontend.c
@@ -755,8 +755,9 @@ static int rtm_to_fib_config(struct net *net, struct sk_buff *skb,
 			break;
 		case RTA_GATEWAY:
 			has_gw = true;
-			cfg->fc_gw_family = AF_INET;
 			cfg->fc_gw4 = nla_get_be32(attr);
+			if (cfg->fc_gw4)
+				cfg->fc_gw_family = AF_INET;
 			break;
 		case RTA_VIA:
 			has_via = true;
diff --git a/net/ipv4/fib_semantics.c b/net/ipv4/fib_semantics.c
index 017273885eee..779d2be2b135 100644
--- a/net/ipv4/fib_semantics.c
+++ b/net/ipv4/fib_semantics.c
@@ -616,8 +616,9 @@ static int fib_get_nhs(struct fib_info *fi, struct rtnexthop *rtnh,
 				return -EINVAL;
 			}
 			if (nla) {
-				fib_cfg.fc_gw_family = AF_INET;
 				fib_cfg.fc_gw4 = nla_get_in_addr(nla);
+				if (fib_cfg.fc_gw4)
+					fib_cfg.fc_gw_family = AF_INET;
 			} else if (nlav) {
 				ret = fib_gw_from_via(&fib_cfg, nlav, extack);
 				if (ret)
-- 
2.11.0