Commits
Mahesh Bandewar committed d4859d749aa
bonding: avoid possible dead-lock
Syzkaller reported this on a slightly older kernel but it's still
applicable to the current kernel -
======================================================
WARNING: possible circular locking dependency detected
4.18.0-next-20180823+ #46 Not tainted
------------------------------------------------------
syz-executor4/26841 is trying to acquire lock:
00000000dd41ef48 ((wq_completion)bond_dev->name){+.+.}, at: flush_workqueue+0x2db/0x1e10 kernel/workqueue.c:2652
but task is already holding lock:
00000000768ab431 (rtnl_mutex){+.+.}, at: rtnl_lock net/core/rtnetlink.c:77 [inline]
00000000768ab431 (rtnl_mutex){+.+.}, at: rtnetlink_rcv_msg+0x412/0xc30 net/core/rtnetlink.c:4708
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #2 (rtnl_mutex){+.+.}:
__mutex_lock_common kernel/locking/mutex.c:925 [inline]
__mutex_lock+0x171/0x1700 kernel/locking/mutex.c:1073
mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1088
rtnl_lock+0x17/0x20 net/core/rtnetlink.c:77
bond_netdev_notify drivers/net/bonding/bond_main.c:1310 [inline]
bond_netdev_notify_work+0x44/0xd0 drivers/net/bonding/bond_main.c:1320
process_one_work+0xc73/0x1aa0 kernel/workqueue.c:2153
worker_thread+0x189/0x13c0 kernel/workqueue.c:2296
kthread+0x35a/0x420 kernel/kthread.c:246
ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:415
-> #1 ((work_completion)(&(&nnw->work)->work)){+.+.}:
process_one_work+0xc0b/0x1aa0 kernel/workqueue.c:2129
worker_thread+0x189/0x13c0 kernel/workqueue.c:2296
kthread+0x35a/0x420 kernel/kthread.c:246
ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:415
-> #0 ((wq_completion)bond_dev->name){+.+.}:
lock_acquire+0x1e4/0x4f0 kernel/locking/lockdep.c:3901
flush_workqueue+0x30a/0x1e10 kernel/workqueue.c:2655
drain_workqueue+0x2a9/0x640 kernel/workqueue.c:2820
destroy_workqueue+0xc6/0x9d0 kernel/workqueue.c:4155
__alloc_workqueue_key+0xef9/0x1190 kernel/workqueue.c:4138
bond_init+0x269/0x940 drivers/net/bonding/bond_main.c:4734
register_netdevice+0x337/0x1100 net/core/dev.c:8410
bond_newlink+0x49/0xa0 drivers/net/bonding/bond_netlink.c:453
rtnl_newlink+0xef4/0x1d50 net/core/rtnetlink.c:3099
rtnetlink_rcv_msg+0x46e/0xc30 net/core/rtnetlink.c:4711
netlink_rcv_skb+0x172/0x440 net/netlink/af_netlink.c:2454
rtnetlink_rcv+0x1c/0x20 net/core/rtnetlink.c:4729
netlink_unicast_kernel net/netlink/af_netlink.c:1317 [inline]
netlink_unicast+0x5a0/0x760 net/netlink/af_netlink.c:1343
netlink_sendmsg+0xa18/0xfc0 net/netlink/af_netlink.c:1908
sock_sendmsg_nosec net/socket.c:622 [inline]
sock_sendmsg+0xd5/0x120 net/socket.c:632
___sys_sendmsg+0x7fd/0x930 net/socket.c:2115
__sys_sendmsg+0x11d/0x290 net/socket.c:2153
__do_sys_sendmsg net/socket.c:2162 [inline]
__se_sys_sendmsg net/socket.c:2160 [inline]
__x64_sys_sendmsg+0x78/0xb0 net/socket.c:2160
do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe
other info that might help us debug this:
Chain exists of:
(wq_completion)bond_dev->name --> (work_completion)(&(&nnw->work)->work) --> rtnl_mutex
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(rtnl_mutex);
lock((work_completion)(&(&nnw->work)->work));
lock(rtnl_mutex);
lock((wq_completion)bond_dev->name);
*** DEADLOCK ***
1 lock held by syz-executor4/26841:
stack backtrace:
CPU: 1 PID: 26841 Comm: syz-executor4 Not tainted 4.18.0-next-20180823+ #46
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_circular_bug.isra.34.cold.55+0x1bd/0x27d kernel/locking/lockdep.c:1222
check_prev_add kernel/locking/lockdep.c:1862 [inline]
check_prevs_add kernel/locking/lockdep.c:1975 [inline]
validate_chain kernel/locking/lockdep.c:2416 [inline]
__lock_acquire+0x3449/0x5020 kernel/locking/lockdep.c:3412
lock_acquire+0x1e4/0x4f0 kernel/locking/lockdep.c:3901
flush_workqueue+0x30a/0x1e10 kernel/workqueue.c:2655
drain_workqueue+0x2a9/0x640 kernel/workqueue.c:2820
destroy_workqueue+0xc6/0x9d0 kernel/workqueue.c:4155
__alloc_workqueue_key+0xef9/0x1190 kernel/workqueue.c:4138
bond_init+0x269/0x940 drivers/net/bonding/bond_main.c:4734
register_netdevice+0x337/0x1100 net/core/dev.c:8410
bond_newlink+0x49/0xa0 drivers/net/bonding/bond_netlink.c:453
rtnl_newlink+0xef4/0x1d50 net/core/rtnetlink.c:3099
rtnetlink_rcv_msg+0x46e/0xc30 net/core/rtnetlink.c:4711
netlink_rcv_skb+0x172/0x440 net/netlink/af_netlink.c:2454
rtnetlink_rcv+0x1c/0x20 net/core/rtnetlink.c:4729
netlink_unicast_kernel net/netlink/af_netlink.c:1317 [inline]
netlink_unicast+0x5a0/0x760 net/netlink/af_netlink.c:1343
netlink_sendmsg+0xa18/0xfc0 net/netlink/af_netlink.c:1908
sock_sendmsg_nosec net/socket.c:622 [inline]
sock_sendmsg+0xd5/0x120 net/socket.c:632
___sys_sendmsg+0x7fd/0x930 net/socket.c:2115
__sys_sendmsg+0x11d/0x290 net/socket.c:2153
__do_sys_sendmsg net/socket.c:2162 [inline]
__se_sys_sendmsg net/socket.c:2160 [inline]
__x64_sys_sendmsg+0x78/0xb0 net/socket.c:2160
do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x457089
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:00007f2df20a5c78 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f2df20a66d4 RCX: 0000000000457089
RDX: 0000000000000000 RSI: 0000000020000180 RDI: 0000000000000003
RBP: 0000000000930140 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 00000000004d40b8 R14: 00000000004c8ad8 R15: 0000000000000001
Signed-off-by: Mahesh Bandewar <maheshb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>