[PATCH v1 net-next 4/5] ipv4: fib: Avoid calling fib_trie_table() in fib_new_table() for dying net.

[Kuniyuki Iwashima <kuniyu@google.com>]

We will call ip_fib_net_exit() from ->exit_rtnl().

All fib_table will be destroyed before devices are unregistered.

During device unregistration, inetdev_destroy() could call
fib_del_ifaddr(), which calls fib_magic(RTM_DELROUTE).

fib_magic() calls fib_new_table(), but we do not want to create
a new table after ip_fib_net_exit() destroys all tables.

As a prep, let's add check_net() before fib_trie_table() in
fib_new_table().

fib_trie_table() is also called from fib_trie_unmerge(), but
fib_get_table() fails first in fib_unmerge(), so the same
problem does not occur there.

Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com>
---
 net/ipv4/fib_frontend.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/ipv4/fib_frontend.c b/net/ipv4/fib_frontend.c
index c3e3b5633fd0..d147471d1d8e 100644
--- a/net/ipv4/fib_frontend.c
+++ b/net/ipv4/fib_frontend.c
@@ -88,7 +88,8 @@ struct fib_table *fib_new_table(struct net *net, u32 id)
 	if (id == RT_TABLE_LOCAL && !net->ipv4.fib_has_custom_rules)
 		alias = fib_new_table(net, RT_TABLE_MAIN);
 
-	tb = fib_trie_table(id, alias);
+	if (check_net(net))
+		tb = fib_trie_table(id, alias);
 	if (!tb)
 		return NULL;
 
-- 
2.54.0.1136.gdb2ca164c4-goog