Commit message: net: hsr: fix memory leak in hsr_dev_finalize()

If hsr_add_port(hsr, hsr_dev, HSR_PT_MASTER) failed to
add port, it directly returns res and forgets to free the node
that allocated in hsr_create_self_node(), and forgets to delete
the node->mac_list linked in hsr->self_node_db.

BUG: memory leak
unreferenced object 0xffff8881cfa0c780 (size 64):
  comm "syz-executor.0", pid 2077, jiffies 4294717969 (age 2415.377s)
  hex dump (first 32 bytes):
    e0 c7 a0 cf 81 88 ff ff 00 02 00 00 00 00 ad de  ................
    00 e6 49 cd 81 88 ff ff c0 9b 87 d0 81 88 ff ff  ..I.............
  backtrace:
    [<00000000e2ff5070>] hsr_dev_finalize+0x736/0x960 [hsr]
    [<000000003ed2e597>] hsr_newlink+0x2b2/0x3e0 [hsr]
    [<000000003fa8c6b6>] __rtnl_newlink+0xf1f/0x1600 net/core/rtnetlink.c:3182
    [<000000001247a7ad>] rtnl_newlink+0x66/0x90 net/core/rtnetlink.c:3240
    [<00000000e7d1b61d>] rtnetlink_rcv_msg+0x54e/0xb90 net/core/rtnetlink.c:5130
    [<000000005556bd3a>] netlink_rcv_skb+0x129/0x340 net/netlink/af_netlink.c:2477
    [<00000000741d5ee6>] netlink_unicast_kernel net/netlink/af_netlink.c:1310 [inline]
    [<00000000741d5ee6>] netlink_unicast+0x49a/0x650 net/netlink/af_netlink.c:1336
    [<000000009d56f9b7>] netlink_sendmsg+0x88b/0xdf0 net/netlink/af_netlink.c:1917
    [<0000000046b35c59>] sock_sendmsg_nosec net/socket.c:621 [inline]
    [<0000000046b35c59>] sock_sendmsg+0xc3/0x100 net/socket.c:631
    [<00000000d208adc9>] __sys_sendto+0x33e/0x560 net/socket.c:1786
    [<00000000b582837a>] __do_sys_sendto net/socket.c:1798 [inline]
    [<00000000b582837a>] __se_sys_sendto net/socket.c:1794 [inline]
    [<00000000b582837a>] __x64_sys_sendto+0xdd/0x1b0 net/socket.c:1794
    [<00000000c866801d>] do_syscall_64+0x147/0x600 arch/x86/entry/common.c:290
    [<00000000fea382d9>] entry_SYSCALL_64_after_hwframe+0x49/0xbe
    [<00000000e01dacb3>] 0xffffffffffffffff

Fixes: c5a759117210 ("net/hsr: Use list_head (and rcu) instead of array for slave devices.")
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Mao Wenan <maowenan@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
CVE: CVE-2019-16995
CWE: CWE-772
Vulnerability description: In the Linux kernel before 5.0.3, a memory leak exits in hsr_dev_finalize() in net/hsr/hsr_device.c if hsr_add_port fails to add a port, which may cause denial of service, aka CID-6caabe7f197d.

Project: linux
File: hsr_device.c

int hsr_dev_finalize(struct net_device *hsr_dev, struct net_device *slave[2],
		     unsigned char multicast_spec, u8 protocol_version)
{
	struct hsr_priv *hsr;
	struct hsr_port *port;
	int res;

	hsr = netdev_priv(hsr_dev);
	INIT_LIST_HEAD(&hsr->ports);
	INIT_LIST_HEAD(&hsr->node_db);
	INIT_LIST_HEAD(&hsr->self_node_db);

	ether_addr_copy(hsr_dev->dev_addr, slave[0]->dev_addr);

	/* Make sure we recognize frames from ourselves in hsr_rcv() */
	res = hsr_create_self_node(&hsr->self_node_db, hsr_dev->dev_addr,
				   slave[1]->dev_addr);
	if (res < 0)
		return res;

	spin_lock_init(&hsr->seqnr_lock);
	/* Overflow soon to find bugs easier: */
	hsr->sequence_nr = HSR_SEQNR_START;
	hsr->sup_sequence_nr = HSR_SUP_SEQNR_START;

	timer_setup(&hsr->announce_timer, hsr_announce, 0);
	timer_setup(&hsr->prune_timer, hsr_prune_nodes, 0);

	ether_addr_copy(hsr->sup_multicast_addr, def_multicast_addr);
	hsr->sup_multicast_addr[ETH_ALEN - 1] = multicast_spec;

	hsr->protVersion = protocol_version;

	/* FIXME: should I modify the value of these?
	 *
	 * - hsr_dev->flags - i.e.
	 *			IFF_MASTER/SLAVE?
	 * - hsr_dev->priv_flags - i.e.
	 *			IFF_EBRIDGE?
	 *			IFF_TX_SKB_SHARING?
	 *			IFF_HSR_MASTER/SLAVE?
	 */

	/* Make sure the 1st call to netif_carrier_on() gets through */
	netif_carrier_off(hsr_dev);
 
 	res = hsr_add_port(hsr, hsr_dev, HSR_PT_MASTER);
 	if (res)
		return res;
 
 	res = register_netdevice(hsr_dev);
 	if (res)
		goto fail;

	res = hsr_add_port(hsr, slave[0], HSR_PT_SLAVE_A);
	if (res)
		goto fail;
	res = hsr_add_port(hsr, slave[1], HSR_PT_SLAVE_B);
	if (res)
		goto fail;

	mod_timer(&hsr->prune_timer, jiffies + msecs_to_jiffies(PRUNE_PERIOD));

	return 0;

 fail:
 	hsr_for_each_port(hsr, port)
 		hsr_del_port(port);
 
 	return res;
 }