geneve: fix hlist corruption

It's not a good idea to add the same hlist_node to two different hash lists.
This leads to various hard to debug memory corruptions.

Fixes: 8ed66f0e ("geneve: implement support for IPv6-based tunnels")
Cc: John W. Linville <linville@tuxdriver.com>
Signed-off-by: Jiri Benc <jbenc@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/geneve.c

@@ -45,9 +45,17 @@ struct geneve_net {
 
 static unsigned int geneve_net_id;
 
+struct geneve_dev_node {
+	struct hlist_node hlist;
+	struct geneve_dev *geneve;
+};
+
 /* Pseudo network device */
 struct geneve_dev {
-	struct hlist_node  hlist;	/* vni hash table */
+	struct geneve_dev_node hlist4;	/* vni hash table for IPv4 socket */
+#if IS_ENABLED(CONFIG_IPV6)
+	struct geneve_dev_node hlist6;	/* vni hash table for IPv6 socket */
+#endif
 	struct net	   *net;	/* netns for packet i/o */
 	struct net_device  *dev;	/* netdev for geneve tunnel */
 	struct ip_tunnel_info info;
@@ -123,16 +131,16 @@ static struct geneve_dev *geneve_lookup(struct geneve_sock *gs,
 					__be32 addr, u8 vni[])
 {
 	struct hlist_head *vni_list_head;
-	struct geneve_dev *geneve;
+	struct geneve_dev_node *node;
 	__u32 hash;
 
 	/* Find the device for this VNI */
 	hash = geneve_net_vni_hash(vni);
 	vni_list_head = &gs->vni_list[hash];
-	hlist_for_each_entry_rcu(geneve, vni_list_head, hlist) {
-		if (eq_tun_id_and_vni((u8 *)&geneve->info.key.tun_id, vni) &&
-		    addr == geneve->info.key.u.ipv4.dst)
-			return geneve;
+	hlist_for_each_entry_rcu(node, vni_list_head, hlist) {
+		if (eq_tun_id_and_vni((u8 *)&node->geneve->info.key.tun_id, vni) &&
+		    addr == node->geneve->info.key.u.ipv4.dst)
+			return node->geneve;
 	}
 	return NULL;
 }
@@ -142,16 +150,16 @@ static struct geneve_dev *geneve6_lookup(struct geneve_sock *gs,
 					 struct in6_addr addr6, u8 vni[])
 {
 	struct hlist_head *vni_list_head;
-	struct geneve_dev *geneve;
+	struct geneve_dev_node *node;
 	__u32 hash;
 
 	/* Find the device for this VNI */
 	hash = geneve_net_vni_hash(vni);
 	vni_list_head = &gs->vni_list[hash];
-	hlist_for_each_entry_rcu(geneve, vni_list_head, hlist) {
-		if (eq_tun_id_and_vni((u8 *)&geneve->info.key.tun_id, vni) &&
-		    ipv6_addr_equal(&addr6, &geneve->info.key.u.ipv6.dst))
-			return geneve;
+	hlist_for_each_entry_rcu(node, vni_list_head, hlist) {
+		if (eq_tun_id_and_vni((u8 *)&node->geneve->info.key.tun_id, vni) &&
+		    ipv6_addr_equal(&addr6, &node->geneve->info.key.u.ipv6.dst))
+			return node->geneve;
 	}
 	return NULL;
 }
@@ -591,6 +599,7 @@ static int geneve_sock_add(struct geneve_dev *geneve, bool ipv6)
 {
 	struct net *net = geneve->net;
 	struct geneve_net *gn = net_generic(net, geneve_net_id);
+	struct geneve_dev_node *node;
 	struct geneve_sock *gs;
 	__u8 vni[3];
 	__u32 hash;
@@ -609,15 +618,20 @@ static int geneve_sock_add(struct geneve_dev *geneve, bool ipv6)
 out:
 	gs->collect_md = geneve->collect_md;
 #if IS_ENABLED(CONFIG_IPV6)
-	if (ipv6)
+	if (ipv6) {
 		rcu_assign_pointer(geneve->sock6, gs);
-	else
+		node = &geneve->hlist6;
+	} else
 #endif
+	{
 		rcu_assign_pointer(geneve->sock4, gs);
+		node = &geneve->hlist4;
+	}
+	node->geneve = geneve;
 
 	tunnel_id_to_vni(geneve->info.key.tun_id, vni);
 	hash = geneve_net_vni_hash(vni);
-	hlist_add_head_rcu(&geneve->hlist, &gs->vni_list[hash]);
+	hlist_add_head_rcu(&node->hlist, &gs->vni_list[hash]);
 	return 0;
 }
 
@@ -644,8 +658,10 @@ static int geneve_stop(struct net_device *dev)
 {
 	struct geneve_dev *geneve = netdev_priv(dev);
 
-	if (!hlist_unhashed(&geneve->hlist))
-		hlist_del_rcu(&geneve->hlist);
+	hlist_del_init_rcu(&geneve->hlist4.hlist);
+#if IS_ENABLED(CONFIG_IPV6)
+	hlist_del_init_rcu(&geneve->hlist6.hlist);
+#endif
 	geneve_sock_release(geneve);
 	return 0;
 }