[PATCH 3.16 294/328] team: Forbid enslaving team device to itself

Ben Hutchings
2018-12-09T22:02:36Z

From: Ido Schimmel <idosch@mellanox.com>

commit 471b83bd8bbe4e89743683ef8ecb78f7029d8288 upstream.

team's ndo_add_slave() acquires 'team->lock' and later tries to open the
newly enslaved device via dev_open(). This emits a 'NETDEV_UP' event
that causes the VLAN driver to add VLAN 0 on the team device. team's
ndo_vlan_rx_add_vid() will also try to acquire 'team->lock' and
deadlock.

Fix this by checking early at the enslavement function that a team
device is not being enslaved to itself.

A similar check was added to the bond driver in commit 09a89c219baf
("bonding: disallow enslaving a bond to itself").

WARNING: possible recursive locking detected
4.18.0-rc7+ #176 Not tainted
--------------------------------------------
syz-executor4/6391 is trying to acquire lock:
(____ptrval____) (&team->lock){+.+.}, at: team_vlan_rx_add_vid+0x3b/0x1e0 drivers/net/team/team.c:1868

but task is already holding lock:
(____ptrval____) (&team->lock){+.+.}, at: team_add_slave+0xdb/0x1c30 drivers/net/team/team.c:1947

other info that might help us debug this:
Possible unsafe locking scenario:

CPU0
----
lock(&team->lock);
lock(&team->lock);

*** DEADLOCK ***

May be due to missing lock nesting notation

2 locks held by syz-executor4/6391:
#0: (____ptrval____) (rtnl_mutex){+.+.}, at: rtnl_lock net/core/rtnetlink.c:77 [inline]
#0: (____ptrval____) (rtnl_mutex){+.+.}, at: rtnetlink_rcv_msg+0x412/0xc30 net/core/rtnetlink.c:4662
#1: (____ptrval____) (&team->lock){+.+.}, at: team_add_slave+0xdb/0x1c30 drivers/net/team/team.c:1947

stack backtrace:
CPU: 1 PID: 6391 Comm: syz-executor4 Not tainted 4.18.0-rc7+ #176
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x1c9/0x2b4 lib/dump_stack.c:113
print_deadlock_bug kernel/locking/lockdep.c:1765 [inline]
check_deadlock kernel/locking/lockdep.c:1809 [inline]
validate_chain kernel/locking/lockdep.c:2405 [inline]
__lock_acquire.cold.64+0x1fb/0x486 kernel/locking/lockdep.c:3435
lock_acquire+0x1e4/0x540 kernel/locking/lockdep.c:3924
__mutex_lock_common kernel/locking/mutex.c:757 [inline]
__mutex_lock+0x176/0x1820 kernel/locking/mutex.c:894
mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:909
team_vlan_rx_add_vid+0x3b/0x1e0 drivers/net/team/team.c:1868
vlan_add_rx_filter_info+0x14a/0x1d0 net/8021q/vlan_core.c:210
__vlan_vid_add net/8021q/vlan_core.c:278 [inline]
vlan_vid_add+0x63e/0x9d0 net/8021q/vlan_core.c:308
vlan_device_event.cold.12+0x2a/0x2f net/8021q/vlan.c:381
notifier_call_chain+0x180/0x390 kernel/notifier.c:93
__raw_notifier_call_chain kernel/notifier.c:394 [inline]
raw_notifier_call_chain+0x2d/0x40 kernel/notifier.c:401
call_netdevice_notifiers_info+0x3f/0x90 net/core/dev.c:1735
call_netdevice_notifiers net/core/dev.c:1753 [inline]
dev_open+0x173/0x1b0 net/core/dev.c:1433
team_port_add drivers/net/team/team.c:1219 [inline]
team_add_slave+0xa8b/0x1c30 drivers/net/team/team.c:1948
do_set_master+0x1c9/0x220 net/core/rtnetlink.c:2248
do_setlink+0xba4/0x3e10 net/core/rtnetlink.c:2382
rtnl_setlink+0x2a9/0x400 net/core/rtnetlink.c:2636
rtnetlink_rcv_msg+0x46e/0xc30 net/core/rtnetlink.c:4665
netlink_rcv_skb+0x172/0x440 net/netlink/af_netlink.c:2455
rtnetlink_rcv+0x1c/0x20 net/core/rtnetlink.c:4683
netlink_unicast_kernel net/netlink/af_netlink.c:1317 [inline]
netlink_unicast+0x5a0/0x760 net/netlink/af_netlink.c:1343
netlink_sendmsg+0xa18/0xfd0 net/netlink/af_netlink.c:1908
sock_sendmsg_nosec net/socket.c:642 [inline]
sock_sendmsg+0xd5/0x120 net/socket.c:652
___sys_sendmsg+0x7fd/0x930 net/socket.c:2126
__sys_sendmsg+0x11d/0x290 net/socket.c:2164
__do_sys_sendmsg net/socket.c:2173 [inline]
__se_sys_sendmsg net/socket.c:2171 [inline]
__x64_sys_sendmsg+0x78/0xb0 net/socket.c:2171
do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x456b29
Code: fd b4 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 cb b4 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f9706bf8c78 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f9706bf96d4 RCX: 0000000000456b29
RDX: 0000000000000000 RSI: 0000000020000240 RDI: 0000000000000004
RBP: 00000000009300a0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 00000000004d3548 R14: 00000000004c8227 R15: 0000000000000000

Fixes: 87002b03baab ("net: introduce vlan_vid_[add/del] and use them instead of direct [add/kill]_vid ndo calls")
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Reported-and-tested-by: syzbot+bd051aba086537515cdb@syzkaller.appspotmail.com
Signed-off-by: David S. Miller <davem@davemloft.net>
[bwh: Backported to 3.16: drop the extack message]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
--- a/drivers/net/team/team.c
+++ b/drivers/net/team/team.c
@@ -1124,6 +1124,11 @@ static int team_port_add(struct team *te
return -EBUSY;
}

+ if (dev == port_dev) {
+ netdev_err(dev, "Cannot enslave team device to itself\n");
+ return -EINVAL;
+ }
+
if (port_dev->features & NETIF_F_VLAN_CHALLENGED &&
vlan_uses_dev(dev)) {
netdev_err(dev, "Device %s is VLAN challenged and team device has VLAN set up\n",