ipv6: initialize route null entry in addrconf_init()

congwang · davem330 · commit 2f460933f58e · 2017-05-04T12:51:24.000-04:00
Andrey reported a crash on init_net.ipv6.ip6_null_entry-&gt;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 &lt;andreyknvl@google.com&gt;
Signed-off-by: Cong Wang &lt;xiyou.wangcong@gmail.com&gt;
Tested-by: Andrey Konovalov &lt;andreyknvl@google.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
diff --git 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
@@ -6573,6 +6573,8 @@ 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
@@ -4027,6 +4027,21 @@ 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;
@@ -4053,17 +4068,6 @@ 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;

Original file line number	Diff line number	Diff line change
`@@ -6573,6 +6573,8 @@ int __init addrconf_init(void)`
`6573`	`6573`	`goto errlo;`
`6574`	`6574`	`}`
`6575`	`6575`
	`6576`	`+ ip6_route_init_special_entries();`
	`6577`	`+`
`6576`	`6578`	`for (i = 0; i < IN6_ADDR_HSIZE; i++)`
`6577`	`6579`	`INIT_HLIST_HEAD(&inet6_addr_lst[i]);`
`6578`	`6580`