Merge branch 'fib-tables-fixes'

Alexander Duyck says:

====================
ipv4: Fix memory leaks and reference issues in fib

This series fixes one major issue and one minor issue in the fib tables.

The major issue is that we had lost the functionality that was flushing the
local table entries from main after we had unmerged the two tries.  In
order to regain the functionality I have performed a partial revert and
then moved the functionality for flushing the external entries from main
into fib_unmerge.

The minor issue was a memory leak that could occur in the event that we
weren't able to add an alias to the local trie resulting in the fib alias
being leaked.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/ip_fib.h

@@ -243,6 +243,7 @@ int fib_table_dump(struct fib_table *table, struct sk_buff *skb,
 		   struct netlink_callback *cb);
 int fib_table_flush(struct net *net, struct fib_table *table);
 struct fib_table *fib_trie_unmerge(struct fib_table *main_tb);
+void fib_table_flush_external(struct fib_table *table);
 void fib_free_table(struct fib_table *tb);
 
 #ifndef CONFIG_IP_MULTIPLE_TABLES

net/ipv4/fib_frontend.c

@@ -151,7 +151,7 @@ static void fib_replace_table(struct net *net, struct fib_table *old,
 
 int fib_unmerge(struct net *net)
 {
-	struct fib_table *old, *new;
+	struct fib_table *old, *new, *main_table;
 
 	/* attempt to fetch local table if it has been allocated */
 	old = fib_get_table(net, RT_TABLE_LOCAL);
@@ -162,11 +162,21 @@ int fib_unmerge(struct net *net)
 	if (!new)
 		return -ENOMEM;
 
+	/* table is already unmerged */
+	if (new == old)
+		return 0;
+
 	/* replace merged table with clean table */
-	if (new != old) {
-		fib_replace_table(net, old, new);
-		fib_free_table(old);
-	}
+	fib_replace_table(net, old, new);
+	fib_free_table(old);
+
+	/* attempt to fetch main table if it has been allocated */
+	main_table = fib_get_table(net, RT_TABLE_MAIN);
+	if (!main_table)
+		return 0;
+
+	/* flush local entries from main table */
+	fib_table_flush_external(main_table);
 
 	return 0;
 }

net/ipv4/fib_trie.c

@@ -1743,8 +1743,10 @@ struct fib_table *fib_trie_unmerge(struct fib_table *oldtb)
 				local_l = fib_find_node(lt, &local_tp, l->key);
 
 			if (fib_insert_alias(lt, local_tp, local_l, new_fa,
-					     NULL, l->key))
+					     NULL, l->key)) {
+				kmem_cache_free(fn_alias_kmem, new_fa);
 				goto out;
+			}
 		}
 
 		/* stop loop if key wrapped back to 0 */
@@ -1760,6 +1762,71 @@ out:
 	return NULL;
 }
 
+/* Caller must hold RTNL */
+void fib_table_flush_external(struct fib_table *tb)
+{
+	struct trie *t = (struct trie *)tb->tb_data;
+	struct key_vector *pn = t->kv;
+	unsigned long cindex = 1;
+	struct hlist_node *tmp;
+	struct fib_alias *fa;
+
+	/* walk trie in reverse order */
+	for (;;) {
+		unsigned char slen = 0;
+		struct key_vector *n;
+
+		if (!(cindex--)) {
+			t_key pkey = pn->key;
+
+			/* cannot resize the trie vector */
+			if (IS_TRIE(pn))
+				break;
+
+			/* resize completed node */
+			pn = resize(t, pn);
+			cindex = get_index(pkey, pn);
+
+			continue;
+		}
+
+		/* grab the next available node */
+		n = get_child(pn, cindex);
+		if (!n)
+			continue;
+
+		if (IS_TNODE(n)) {
+			/* record pn and cindex for leaf walking */
+			pn = n;
+			cindex = 1ul << n->bits;
+
+			continue;
+		}
+
+		hlist_for_each_entry_safe(fa, tmp, &n->leaf, fa_list) {
+			/* if alias was cloned to local then we just
+			 * need to remove the local copy from main
+			 */
+			if (tb->tb_id != fa->tb_id) {
+				hlist_del_rcu(&fa->fa_list);
+				alias_free_mem_rcu(fa);
+				continue;
+			}
+
+			/* record local slen */
+			slen = fa->fa_slen;
+		}
+
+		/* update leaf slen */
+		n->slen = slen;
+
+		if (hlist_empty(&n->leaf)) {
+			put_child_root(pn, n->key, NULL);
+			node_free(n);
+		}
+	}
+}
+
 /* Caller must hold RTNL. */
 int fib_table_flush(struct net *net, struct fib_table *tb)
 {