[PATCH 3.2 42/61] ipv6: fix memory leak with multiple tables during netns destruction

[Ben Hutchings <ben@decadent.org.uk>]

3.2.96-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Sabrina Dubroca <sd@queasysnail.net>

commit ba1cc08d9488c94cb8d94f545305688b72a2a300 upstream.

fib6_net_exit only frees the main and local tables. If another table was
created with fib6_alloc_table, we leak it when the netns is destroyed.

Fix this in the same way ip_fib_net_exit cleans up tables, by walking
through the whole hashtable of fib6_table's. We can get rid of the
special cases for local and main, since they're also part of the
hashtable.

Reproducer:
    ip netns add x
    ip -net x -6 rule add from 6003:1::/64 table 100
    ip netns del x

Reported-by: Jianlin Shi <jishi@redhat.com>
Fixes: 58f09b78b730 ("[NETNS][IPV6] ip6_fib - make it per network namespace")
Signed-off-by: Sabrina Dubroca <sd@queasysnail.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
[bwh: Backported to 3.2:
 - No need to call inetpeer_invalidate_tree()
 - Add the extra iterator variable needed by hlist_for_each_entry_safe()]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
--- a/net/ipv6/ip6_fib.c
+++ b/net/ipv6/ip6_fib.c
@@ -1577,13 +1577,22 @@ out_timer:
 
 static void fib6_net_exit(struct net *net)
 {
+	unsigned int i;
+
 	rt6_ifdown(net, NULL);
 	del_timer_sync(&net->ipv6.ip6_fib_timer);
 
-#ifdef CONFIG_IPV6_MULTIPLE_TABLES
-	kfree(net->ipv6.fib6_local_tbl);
-#endif
-	kfree(net->ipv6.fib6_main_tbl);
+	for (i = 0; i < FIB_TABLE_HASHSZ; i++) {
+		struct hlist_head *head = &net->ipv6.fib_table_hash[i];
+		struct hlist_node *node, *tmp;
+		struct fib6_table *tb;
+
+		hlist_for_each_entry_safe(tb, node, tmp, head, tb6_hlist) {
+			hlist_del(&tb->tb6_hlist);
+			kfree(tb);
+		}
+	}
+
 	kfree(net->ipv6.fib_table_hash);
 	kfree(net->ipv6.rt6_stats);
 }