[PATCH] net: route: Fix vrf dst_entry ref count false increasing

From: linmiaohe
Date: Sat May 04 2019 - 04:04:23 EST

From: Suanming.Mou <mousuanming@xxxxxxxxxx>

When config ip in default vrf same as the ip in specified
vrf, fib_lookup will return the route from table local
even if the in device is an enslaved l3mdev. Then the
dst_entry will hold the vrf device rather than loopback
device in local_input of function ip_route_input_slow.
So vrf dst_entry is false increased by route from table

Here is reproduce step:
1.enslave enp4s0 to vrf2, and config ip address:
ip link add vrf2 type vrf table 1
ip link set vrf2 up
ip link set enp4s0 master vrf2
ip addr ad dev enp4s0

2.config same ip in default vrf:
ip addr ad dev enp6s0

3.config peer and ping:
ip vrf exec vrf2 ping -c 3

4.del vrf2 link:
ip link del vrf2

And "unregister_netdevice: waiting for vrf2 to become free.
Usage count = 1" will occur.

Signed-off-by: Suanming.Mou <mousuanming@xxxxxxxxxx>
Signed-off-by: Miaohe Lin <linmiaohe@xxxxxxxxxx>
net/core/fib_rules.c | 5 +++++
1 file changed, 5 insertions(+)

diff --git a/net/core/fib_rules.c b/net/core/fib_rules.c
index ffbb827723a2..1a2c11ed1585 100644
--- a/net/core/fib_rules.c
+++ b/net/core/fib_rules.c
@@ -263,6 +263,11 @@ static int fib_rule_match(struct fib_rule *rule, struct fib_rules_ops *ops,
if (rule->tun_id && (rule->tun_id != fl->flowi_tun_key.tun_id))
goto out;

+ if (!rule->l3mdev &&
+ (netif_index_is_l3_master(rule->fr_net, fl->flowi_iif) ||
+ netif_index_is_l3_master(rule->fr_net, fl->flowi_oif)))
+ goto out;
if (rule->l3mdev && !l3mdev_fib_rule_match(rule->fr_net, fl, arg))
goto out;