ipv6: initialize route null entry in addrconf_init()

[ Upstream commit 2f460933f58eee3393aba64f0f6d14acb08d1724 ]

Andrey reported a crash on init_net.ipv6.ip6_null_entry->rt6i_idev
since it is always NULL.

This is clearly wrong, we have code to initialize it to loopback_dev,
unfortunately the order is still not correct.

loopback_dev is registered very early during boot, we lose a chance
to re-initialize it in notifier. addrconf_init() is called after
ip6_route_init(), which means we have no chance to correct it.

Fix it by moving this initialization explicitly after
ipv6_add_dev(init_net.loopback_dev) in addrconf_init().

Reported-by: Andrey Konovalov <andreyknvl@google.com>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Tested-by: Andrey Konovalov <andreyknvl@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

3 files changed, 18 insertions, 11 deletions

diff --git a/include/net/ip6_route.h b/include/net/ip6_route.h
index f83e78d071a3..2e347d4545cf 100644
--- a/include/net/ip6_route.h
+++ b/include/net/ip6_route.h
@@ -84,6 +84,7 @@ struct dst_entry *ip6_route_lookup(struct net *net, struct flowi6 *fl6,
 struct rt6_info *ip6_pol_route(struct net *net, struct fib6_table *table,
                                int ifindex, struct flowi6 *fl6, int flags);
 
+void ip6_route_init_special_entries(void);
 int ip6_route_init(void);
 void ip6_route_cleanup(void);
 
diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index e0a083f49227..4d115b5cb231 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -6264,6 +6264,8 @@ int __init addrconf_init(void)
                 goto errlo;
         }
 
+        ip6_route_init_special_entries();
+
         for (i = 0; i < IN6_ADDR_HSIZE; i++)
                 INIT_HLIST_HEAD(&inet6_addr_lst[i]);
 
diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 9f1bc756799a..57081bbf21d6 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -3798,6 +3798,21 @@ static struct notifier_block ip6_route_dev_notifier = {
         .priority = 0,
 };
 
+void __init ip6_route_init_special_entries(void)
+{
+        /* Registering of the loopback is done before this portion of code,
+         * the loopback reference in rt6_info will not be taken, do it
+         * manually for init_net */
+        init_net.ipv6.ip6_null_entry->dst.dev = init_net.loopback_dev;
+        init_net.ipv6.ip6_null_entry->rt6i_idev = in6_dev_get(init_net.loopback_dev);
+  #ifdef CONFIG_IPV6_MULTIPLE_TABLES
+        init_net.ipv6.ip6_prohibit_entry->dst.dev = init_net.loopback_dev;
+        init_net.ipv6.ip6_prohibit_entry->rt6i_idev = in6_dev_get(init_net.loopback_dev);
+        init_net.ipv6.ip6_blk_hole_entry->dst.dev = init_net.loopback_dev;
+        init_net.ipv6.ip6_blk_hole_entry->rt6i_idev = in6_dev_get(init_net.loopback_dev);
+  #endif
+}
+
 int __init ip6_route_init(void)
 {
         int ret;
@@ -3824,17 +3839,6 @@ int __init ip6_route_init(void)
 
         ip6_dst_blackhole_ops.kmem_cachep = ip6_dst_ops_template.kmem_cachep;
 
-        /* Registering of the loopback is done before this portion of code,
-         * the loopback reference in rt6_info will not be taken, do it
-         * manually for init_net */
-        init_net.ipv6.ip6_null_entry->dst.dev = init_net.loopback_dev;
-        init_net.ipv6.ip6_null_entry->rt6i_idev = in6_dev_get(init_net.loopback_dev);
-  #ifdef CONFIG_IPV6_MULTIPLE_TABLES
-        init_net.ipv6.ip6_prohibit_entry->dst.dev = init_net.loopback_dev;
-        init_net.ipv6.ip6_prohibit_entry->rt6i_idev = in6_dev_get(init_net.loopback_dev);
-        init_net.ipv6.ip6_blk_hole_entry->dst.dev = init_net.loopback_dev;
-        init_net.ipv6.ip6_blk_hole_entry->rt6i_idev = in6_dev_get(init_net.loopback_dev);
-  #endif
         ret = fib6_init();
         if (ret)
                 goto out_register_subsys;