Re: possible deadlock in dev_uc_sync

From: syzbot
Date: Mon Oct 12 2020 - 03:03:16 EST


syzbot has found a reproducer for the following issue on:

HEAD commit: 3dd0130f Merge branch 'akpm' (patches from Andrew)
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=16b36120500000
kernel config: https://syzkaller.appspot.com/x/.config?x=c06bcf3cc963d91c
dashboard link: https://syzkaller.appspot.com/bug?extid=4a0f7bc34e3997a6c7df
compiler: gcc (GCC) 10.1.0-syz 20200507
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=105cbfb8500000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=13193ce8500000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+4a0f7bc34e3997a6c7df@xxxxxxxxxxxxxxxxxxxxxxxxx

======================================================
WARNING: possible circular locking dependency detected
5.9.0-rc8-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor655/7496 is trying to acquire lock:
ffff888092808280 (&dev_addr_list_lock_key/2){+...}-{2:2}, at: netif_addr_lock include/linux/netdevice.h:4281 [inline]
ffff888092808280 (&dev_addr_list_lock_key/2){+...}-{2:2}, at: dev_uc_sync+0xdc/0x190 net/core/dev_addr_lists.c:640

but task is already holding lock:
ffff888087efa280 (&macvlan_netdev_addr_lock_key/1){+...}-{2:2}, at: netif_addr_lock_bh include/linux/netdevice.h:4292 [inline]
ffff888087efa280 (&macvlan_netdev_addr_lock_key/1){+...}-{2:2}, at: dev_set_rx_mode net/core/dev.c:8274 [inline]
ffff888087efa280 (&macvlan_netdev_addr_lock_key/1){+...}-{2:2}, at: __dev_open+0x368/0x4d0 net/core/dev.c:1529

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&macvlan_netdev_addr_lock_key/1){+...}-{2:2}:
_raw_spin_lock_nested+0x30/0x40 kernel/locking/spinlock.c:361
netif_addr_lock include/linux/netdevice.h:4281 [inline]
dev_uc_sync+0xdc/0x190 net/core/dev_addr_lists.c:640
bond_hw_addr_swap drivers/net/bonding/bond_main.c:740 [inline]
bond_change_active_slave+0xc3d/0x20d0 drivers/net/bonding/bond_main.c:1007
bond_select_active_slave+0x28d/0xa40 drivers/net/bonding/bond_main.c:1093
bond_enslave+0x4441/0x49a0 drivers/net/bonding/bond_main.c:1947
do_set_master+0x1c8/0x220 net/core/rtnetlink.c:2517
__rtnl_newlink+0x132a/0x1740 net/core/rtnetlink.c:3469
rtnl_newlink+0x64/0xa0 net/core/rtnetlink.c:3500
rtnetlink_rcv_msg+0x44e/0xad0 net/core/rtnetlink.c:5563
netlink_rcv_skb+0x15a/0x430 net/netlink/af_netlink.c:2470
netlink_unicast_kernel net/netlink/af_netlink.c:1304 [inline]
netlink_unicast+0x533/0x7d0 net/netlink/af_netlink.c:1330
netlink_sendmsg+0x856/0xd90 net/netlink/af_netlink.c:1919
sock_sendmsg_nosec net/socket.c:651 [inline]
sock_sendmsg+0xcf/0x120 net/socket.c:671
____sys_sendmsg+0x6e8/0x810 net/socket.c:2353
___sys_sendmsg+0xf3/0x170 net/socket.c:2407
__sys_sendmsg+0xe5/0x1b0 net/socket.c:2440
do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xa9

-> #0 (&dev_addr_list_lock_key/2){+...}-{2:2}:
check_prev_add kernel/locking/lockdep.c:2496 [inline]
check_prevs_add kernel/locking/lockdep.c:2601 [inline]
validate_chain kernel/locking/lockdep.c:3218 [inline]
__lock_acquire+0x2a96/0x5780 kernel/locking/lockdep.c:4441
lock_acquire+0x1f3/0xaf0 kernel/locking/lockdep.c:5029
_raw_spin_lock_nested+0x30/0x40 kernel/locking/spinlock.c:361
netif_addr_lock include/linux/netdevice.h:4281 [inline]
dev_uc_sync+0xdc/0x190 net/core/dev_addr_lists.c:640
macvlan_set_mac_lists+0x55/0x110 drivers/net/macvlan.c:802
__dev_set_rx_mode+0x1e2/0x2e0 net/core/dev.c:8269
dev_set_rx_mode net/core/dev.c:8275 [inline]
__dev_open+0x370/0x4d0 net/core/dev.c:1529
dev_open net/core/dev.c:1557 [inline]
dev_open+0xe8/0x150 net/core/dev.c:1550
bond_enslave+0x927/0x49a0 drivers/net/bonding/bond_main.c:1728
do_set_master+0x1c8/0x220 net/core/rtnetlink.c:2517
__rtnl_newlink+0x132a/0x1740 net/core/rtnetlink.c:3469
rtnl_newlink+0x64/0xa0 net/core/rtnetlink.c:3500
rtnetlink_rcv_msg+0x44e/0xad0 net/core/rtnetlink.c:5563
netlink_rcv_skb+0x15a/0x430 net/netlink/af_netlink.c:2470
netlink_unicast_kernel net/netlink/af_netlink.c:1304 [inline]
netlink_unicast+0x533/0x7d0 net/netlink/af_netlink.c:1330
netlink_sendmsg+0x856/0xd90 net/netlink/af_netlink.c:1919
sock_sendmsg_nosec net/socket.c:651 [inline]
sock_sendmsg+0xcf/0x120 net/socket.c:671
____sys_sendmsg+0x6e8/0x810 net/socket.c:2353
___sys_sendmsg+0xf3/0x170 net/socket.c:2407
__sys_sendmsg+0xe5/0x1b0 net/socket.c:2440
do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xa9

other info that might help us debug this:

Possible unsafe locking scenario:

CPU0 CPU1
---- ----
lock(&macvlan_netdev_addr_lock_key/1);
lock(&dev_addr_list_lock_key/2);
lock(&macvlan_netdev_addr_lock_key/1);
lock(&dev_addr_list_lock_key/2);

*** DEADLOCK ***

2 locks held by syz-executor655/7496:
#0: ffffffff8b150908 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:72 [inline]
#0: ffffffff8b150908 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x3f9/0xad0 net/core/rtnetlink.c:5560
#1: ffff888087efa280 (&macvlan_netdev_addr_lock_key/1){+...}-{2:2}, at: netif_addr_lock_bh include/linux/netdevice.h:4292 [inline]
#1: ffff888087efa280 (&macvlan_netdev_addr_lock_key/1){+...}-{2:2}, at: dev_set_rx_mode net/core/dev.c:8274 [inline]
#1: ffff888087efa280 (&macvlan_netdev_addr_lock_key/1){+...}-{2:2}, at: __dev_open+0x368/0x4d0 net/core/dev.c:1529

stack backtrace:
CPU: 0 PID: 7496 Comm: syz-executor655 Not tainted 5.9.0-rc8-syzkaller #0
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+0x198/0x1fd lib/dump_stack.c:118
check_noncircular+0x324/0x3e0 kernel/locking/lockdep.c:1827
check_prev_add kernel/locking/lockdep.c:2496 [inline]
check_prevs_add kernel/locking/lockdep.c:2601 [inline]
validate_chain kernel/locking/lockdep.c:3218 [inline]
__lock_acquire+0x2a96/0x5780 kernel/locking/lockdep.c:4441
lock_acquire+0x1f3/0xaf0 kernel/locking/lockdep.c:5029
_raw_spin_lock_nested+0x30/0x40 kernel/locking/spinlock.c:361
netif_addr_lock include/linux/netdevice.h:4281 [inline]
dev_uc_sync+0xdc/0x190 net/core/dev_addr_lists.c:640
macvlan_set_mac_lists+0x55/0x110 drivers/net/macvlan.c:802
__dev_set_rx_mode+0x1e2/0x2e0 net/core/dev.c:8269
dev_set_rx_mode net/core/dev.c:8275 [inline]
__dev_open+0x370/0x4d0 net/core/dev.c:1529
dev_open net/core/dev.c:1557 [inline]
dev_open+0xe8/0x150 net/core/dev.c:1550
bond_enslave+0x927/0x49a0 drivers/net/bonding/bond_main.c:1728
do_set_master+0x1c8/0x220 net/core/rtnetlink.c:2517
__rtnl_newlink+0x132a/0x1740 net/core/rtnetlink.c:3469
rtnl_newlink+0x64/0xa0 net/core/rtnetlink.c:3500
rtnetlink_rcv_msg+0x44e/0xad0 net/core/rtnetlink.c:5563
netlink_rcv_skb+0x15a/0x430 net/netlink/af_netlink.c:2470
netlink_unicast_kernel net/netlink/af_netlink.c:1304 [inline]
netlink_unicast+0x533/0x7d0 net/netlink/af_netlink.c:1330
netlink_sendmsg+0x856/0xd90 net/netlink/af_netlink.c:1919
sock_sendmsg_nosec net/socket.c:651 [inline]
sock_sendmsg+0xcf/0x120 net/socket.c:671
____sys_sendmsg+0x6e8/0x810 net/socket.c:2353
___sys_sendmsg+0xf3/0x170 net/socket.c:2407
__sys_sendmsg+0xe5/0x1b0 net/socket.c:2440
do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x449b39
Code: e8 cc 0c 03 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 0b 06 fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007fb38e3d4d98 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00000000006dfca8 RCX: 0000000000449b39
RDX: 0000000000000000 RSI: 0000000020000340 RDI: 0000000000000008
RBP: 00000000006dfca0 R08: 00007fb38e3d5700 R09: 0000000000000000
R10: 00007fb38e3d5700 R11: 0000000000000246 R12: 00000000006dfcac
R13: 00000000000003ff R14: 0000003f797fa400 R15: 070d00100000003c
bond9: (slave macvlan9): Enslaving as an active interface with a down link