[PATCH 4.9 18/32] bonding: avoid lockdep confusion in bond_get_stats()

Greg Kroah-Hartman
2018-08-04T09:05:31Z

From: Eric Dumazet <edumazet@google.com>

[ Upstream commit 7e2556e40026a1b0c16f37446ab398d5a5a892e4 ]

syzbot found that the following sequence produces a LOCKDEP splat [1]

ip link add bond10 type bond
ip link add bond11 type bond
ip link set bond11 master bond10

To fix this, we can use the already provided nest_level.

This patch also provides correct nesting for dev->addr_list_lock

[1]
WARNING: possible recursive locking detected
4.18.0-rc6+ #167 Not tainted
--------------------------------------------
syz-executor751/4439 is trying to acquire lock:
(____ptrval____) (&(&bond->stats_lock)->rlock){+.+.}, at: spin_lock include/linux/spinlock.h:310 [inline]
(____ptrval____) (&(&bond->stats_lock)->rlock){+.+.}, at: bond_get_stats+0xb4/0x560 drivers/net/bonding/bond_main.c:3426

but task is already holding lock:
(____ptrval____) (&(&bond->stats_lock)->rlock){+.+.}, at: spin_lock include/linux/spinlock.h:310 [inline]
(____ptrval____) (&(&bond->stats_lock)->rlock){+.+.}, at: bond_get_stats+0xb4/0x560 drivers/net/bonding/bond_main.c:3426

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

CPU0
----
lock(&(&bond->stats_lock)->rlock);
lock(&(&bond->stats_lock)->rlock);

*** DEADLOCK ***

May be due to missing lock nesting notation

3 locks held by syz-executor751/4439:
#0: (____ptrval____) (rtnl_mutex){+.+.}, at: rtnl_lock+0x17/0x20 net/core/rtnetlink.c:77
#1: (____ptrval____) (&(&bond->stats_lock)->rlock){+.+.}, at: spin_lock include/linux/spinlock.h:310 [inline]
#1: (____ptrval____) (&(&bond->stats_lock)->rlock){+.+.}, at: bond_get_stats+0xb4/0x560 drivers/net/bonding/bond_main.c:3426
#2: (____ptrval____) (rcu_read_lock){....}, at: bond_get_stats+0x0/0x560 include/linux/compiler.h:215

stack backtrace:
CPU: 0 PID: 4439 Comm: syz-executor751 Not tainted 4.18.0-rc6+ #167
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
__raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline]
_raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:144
spin_lock include/linux/spinlock.h:310 [inline]
bond_get_stats+0xb4/0x560 drivers/net/bonding/bond_main.c:3426
dev_get_stats+0x10f/0x470 net/core/dev.c:8316
bond_get_stats+0x232/0x560 drivers/net/bonding/bond_main.c:3432
dev_get_stats+0x10f/0x470 net/core/dev.c:8316
rtnl_fill_stats+0x4d/0xac0 net/core/rtnetlink.c:1169
rtnl_fill_ifinfo+0x1aa6/0x3fb0 net/core/rtnetlink.c:1611
rtmsg_ifinfo_build_skb+0xc8/0x190 net/core/rtnetlink.c:3268
rtmsg_ifinfo_event.part.30+0x45/0xe0 net/core/rtnetlink.c:3300
rtmsg_ifinfo_event net/core/rtnetlink.c:3297 [inline]
rtnetlink_event+0x144/0x170 net/core/rtnetlink.c:4716
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]
netdev_features_change net/core/dev.c:1321 [inline]
netdev_change_features+0xb3/0x110 net/core/dev.c:7759
bond_compute_features.isra.47+0x585/0xa50 drivers/net/bonding/bond_main.c:1120
bond_enslave+0x1b25/0x5da0 drivers/net/bonding/bond_main.c:1755
bond_do_ioctl+0x7cb/0xae0 drivers/net/bonding/bond_main.c:3528
dev_ifsioc+0x43c/0xb30 net/core/dev_ioctl.c:327
dev_ioctl+0x1b5/0xcc0 net/core/dev_ioctl.c:493
sock_do_ioctl+0x1d3/0x3e0 net/socket.c:992
sock_ioctl+0x30d/0x680 net/socket.c:1093
vfs_ioctl fs/ioctl.c:46 [inline]
file_ioctl fs/ioctl.c:500 [inline]
do_vfs_ioctl+0x1de/0x1720 fs/ioctl.c:684
ksys_ioctl+0xa9/0xd0 fs/ioctl.c:701
__do_sys_ioctl fs/ioctl.c:708 [inline]
__se_sys_ioctl fs/ioctl.c:706 [inline]
__x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:706
do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x440859
Code: e8 2c af 02 00 48 83 c4 18 c3 0f 1f 80 00 00 00 00 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 3b 10 fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007ffc51a92878 EFLAGS: 00000213 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000440859
RDX: 0000000020000040 RSI: 0000000000008990 RDI: 0000000000000003
RBP: 0000000000000000 R08: 00000000004002c8 R09: 00000000004002c8
R10: 00000000022d5880 R11: 0000000000000213 R12: 0000000000007390
R13: 0000000000401db0 R14: 0000000000000000 R15: 0000000000000000

Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Jay Vosburgh <j.vosburgh@gmail.com>
Cc: Veaceslav Falico <vfalico@gmail.com>
Cc: Andy Gospodarek <andy@greyhouse.net>

Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/net/bonding/bond_main.c | 14 ++++++++++++--
1 file changed, 12 insertions(+), 2 deletions(-)

--- a/drivers/net/bonding/bond_main.c
+++ b/drivers/net/bonding/bond_main.c
@@ -1682,6 +1682,8 @@ int bond_enslave(struct net_device *bond
goto err_upper_unlink;
}

+ bond->nest_level = dev_get_nest_level(bond_dev) + 1;
+
/* If the mode uses primary, then the following is handled by
* bond_change_active_slave().
*/
@@ -1729,7 +1731,6 @@ int bond_enslave(struct net_device *bond
if (bond_mode_uses_xmit_hash(bond))
bond_update_slave_arr(bond, NULL);

- bond->nest_level = dev_get_nest_level(bond_dev);

netdev_info(bond_dev, "Enslaving %s as %s interface with %s link\n",
slave_dev->name,
@@ -3359,6 +3360,13 @@ static void bond_fold_stats(struct rtnl_
}
}

+static int bond_get_nest_level(struct net_device *bond_dev)
+{
+ struct bonding *bond = netdev_priv(bond_dev);
+
+ return bond->nest_level;
+}
+
static struct rtnl_link_stats64 *bond_get_stats(struct net_device *bond_dev,
struct rtnl_link_stats64 *stats)
{
@@ -3367,7 +3375,7 @@ static struct rtnl_link_stats64 *bond_ge
struct list_head *iter;
struct slave *slave;

- spin_lock(&bond->stats_lock);
+ spin_lock_nested(&bond->stats_lock, bond_get_nest_level(bond_dev));
memcpy(stats, &bond->bond_stats, sizeof(*stats));

rcu_read_lock();
@@ -4163,6 +4171,7 @@ static const struct net_device_ops bond_
.ndo_neigh_setup = bond_neigh_setup,
.ndo_vlan_rx_add_vid = bond_vlan_rx_add_vid,
.ndo_vlan_rx_kill_vid = bond_vlan_rx_kill_vid,
+ .ndo_get_lock_subclass = bond_get_nest_level,
#ifdef CONFIG_NET_POLL_CONTROLLER
.ndo_netpoll_setup = bond_netpoll_setup,
.ndo_netpoll_cleanup = bond_netpoll_cleanup,
@@ -4655,6 +4664,7 @@ static int bond_init(struct net_device *
if (!bond->wq)
return -ENOMEM;

+ bond->nest_level = SINGLE_DEPTH_NESTING;
netdev_lockdep_set_classes(bond_dev);

list_add_tail(&bond->bond_list, &bn->dev_list);