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Subject[PATCH 4.14 16/59] bonding: update nest level on unlink
Date
4.14-stable review patch.  If anyone has any objections, please let me know.

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

From: Willem de Bruijn <willemb@google.com>

[ Upstream commit 001e465f09a18857443489a57e74314a3368c805 ]

A network device stack with multiple layers of bonding devices can
trigger a false positive lockdep warning. Adding lockdep nest levels
fixes this. Update the level on both enslave and unlink, to avoid the
following series of events ..

ip netns add test
ip netns exec test bash
ip link set dev lo addr 00:11:22:33:44:55
ip link set dev lo down

ip link add dev bond1 type bond
ip link add dev bond2 type bond

ip link set dev lo master bond1
ip link set dev bond1 master bond2

ip link set dev bond1 nomaster
ip link set dev bond2 master bond1

.. from still generating a splat:

[ 193.652127] ======================================================
[ 193.658231] WARNING: possible circular locking dependency detected
[ 193.664350] 4.20.0 #8 Not tainted
[ 193.668310] ------------------------------------------------------
[ 193.674417] ip/15577 is trying to acquire lock:
[ 193.678897] 00000000a40e3b69 (&(&bond->stats_lock)->rlock#3/3){+.+.}, at: bond_get_stats+0x58/0x290
[ 193.687851]
but task is already holding lock:
[ 193.693625] 00000000807b9d9f (&(&bond->stats_lock)->rlock#2/2){+.+.}, at: bond_get_stats+0x58/0x290

[..]

[ 193.851092] lock_acquire+0xa7/0x190
[ 193.855138] _raw_spin_lock_nested+0x2d/0x40
[ 193.859878] bond_get_stats+0x58/0x290
[ 193.864093] dev_get_stats+0x5a/0xc0
[ 193.868140] bond_get_stats+0x105/0x290
[ 193.872444] dev_get_stats+0x5a/0xc0
[ 193.876493] rtnl_fill_stats+0x40/0x130
[ 193.880797] rtnl_fill_ifinfo+0x6c5/0xdc0
[ 193.885271] rtmsg_ifinfo_build_skb+0x86/0xe0
[ 193.890091] rtnetlink_event+0x5b/0xa0
[ 193.894320] raw_notifier_call_chain+0x43/0x60
[ 193.899225] netdev_change_features+0x50/0xa0
[ 193.904044] bond_compute_features.isra.46+0x1ab/0x270
[ 193.909640] bond_enslave+0x141d/0x15b0
[ 193.913946] do_set_master+0x89/0xa0
[ 193.918016] do_setlink+0x37c/0xda0
[ 193.921980] __rtnl_newlink+0x499/0x890
[ 193.926281] rtnl_newlink+0x48/0x70
[ 193.930238] rtnetlink_rcv_msg+0x171/0x4b0
[ 193.934801] netlink_rcv_skb+0xd1/0x110
[ 193.939103] rtnetlink_rcv+0x15/0x20
[ 193.943151] netlink_unicast+0x3b5/0x520
[ 193.947544] netlink_sendmsg+0x2fd/0x3f0
[ 193.951942] sock_sendmsg+0x38/0x50
[ 193.955899] ___sys_sendmsg+0x2ba/0x2d0
[ 193.960205] __x64_sys_sendmsg+0xad/0x100
[ 193.964687] do_syscall_64+0x5a/0x460
[ 193.968823] entry_SYSCALL_64_after_hwframe+0x49/0xbe

Fixes: 7e2556e40026 ("bonding: avoid lockdep confusion in bond_get_stats()")
Reported-by: syzbot <syzkaller@googlegroups.com>
Signed-off-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/net/bonding/bond_main.c | 3 +++
1 file changed, 3 insertions(+)

--- a/drivers/net/bonding/bond_main.c
+++ b/drivers/net/bonding/bond_main.c
@@ -1928,6 +1928,9 @@ static int __bond_release_one(struct net
if (!bond_has_slaves(bond)) {
bond_set_carrier(bond);
eth_hw_addr_random(bond_dev);
+ bond->nest_level = SINGLE_DEPTH_NESTING;
+ } else {
+ bond->nest_level = dev_get_nest_level(bond_dev) + 1;
}

unblock_netpoll_tx();

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