linux-kernel - Re: [syzbot] [net?] possible deadlock in team_port_change

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Date: Thu, 07 Mar 2024 01:50:02 -0800
From: syzbot <syzbot+3c47b5843403a45aef57@...kaller.appspotmail.com>
To: eadavis@...com, linux-kernel@...r.kernel.org, 
	syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [net?] possible deadlock in team_port_change_check (2)

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
possible deadlock in team_port_change_check

veth0_vlan: left promiscuous mode
veth0_vlan: entered promiscuous mode
team0: Device veth0_vlan failed to register rx_handler
============================================
WARNING: possible recursive locking detected
6.8.0-rc7-syzkaller-00051-g67be068d31d4-dirty #0 Not tainted
--------------------------------------------
syz-executor.0/5487 is trying to acquire lock:
ffff88802dce4d00 (team->team_lock_key){+.+.}-{3:3}, at: team_port_change_check+0x51/0x1e0 drivers/net/team/team.c:2999

but task is already holding lock:
ffff88802dce4d00 (team->team_lock_key){+.+.}-{3:3}, at: team_port_add drivers/net/team/team.c:1217 [inline]
ffff88802dce4d00 (team->team_lock_key){+.+.}-{3:3}, at: team_add_slave+0x9bb/0x2710 drivers/net/team/team.c:1977

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

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

 *** DEADLOCK ***

 May be due to missing lock nesting notation

2 locks held by syz-executor.0/5487:
 #0: ffffffff8f375d88 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:79 [inline]
 #0: ffffffff8f375d88 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x82c/0x1040 net/core/rtnetlink.c:6614
 #1: ffff88802dce4d00 (team->team_lock_key){+.+.}-{3:3}, at: team_port_add drivers/net/team/team.c:1217 [inline]
 #1: ffff88802dce4d00 (team->team_lock_key){+.+.}-{3:3}, at: team_add_slave+0x9bb/0x2710 drivers/net/team/team.c:1977

stack backtrace:
CPU: 1 PID: 5487 Comm: syz-executor.0 Not tainted 6.8.0-rc7-syzkaller-00051-g67be068d31d4-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/25/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1e7/0x2e0 lib/dump_stack.c:106
 check_deadlock kernel/locking/lockdep.c:3062 [inline]
 validate_chain+0x15c0/0x58e0 kernel/locking/lockdep.c:3856
 __lock_acquire+0x1345/0x1fd0 kernel/locking/lockdep.c:5137
 lock_acquire+0x1e3/0x530 kernel/locking/lockdep.c:5754
 __mutex_lock_common kernel/locking/mutex.c:608 [inline]
 __mutex_lock+0x136/0xd70 kernel/locking/mutex.c:752
 team_port_change_check+0x51/0x1e0 drivers/net/team/team.c:2999
 team_device_event+0x161/0x5b0 drivers/net/team/team.c:3025
 notifier_call_chain+0x18f/0x3b0 kernel/notifier.c:93
 call_netdevice_notifiers_extack net/core/dev.c:2004 [inline]
 call_netdevice_notifiers net/core/dev.c:2018 [inline]
 dev_close_many+0x33c/0x4c0 net/core/dev.c:1559
 vlan_device_event+0x18b7/0x1de0 net/8021q/vlan.c:449
 notifier_call_chain+0x18f/0x3b0 kernel/notifier.c:93
 call_netdevice_notifiers_extack net/core/dev.c:2004 [inline]
 call_netdevice_notifiers net/core/dev.c:2018 [inline]
 dev_close_many+0x33c/0x4c0 net/core/dev.c:1559
 dev_close+0x1c0/0x2c0 net/core/dev.c:1581
 team_port_add drivers/net/team/team.c:1314 [inline]
 team_add_slave+0x1ac5/0x2710 drivers/net/team/team.c:1977
 do_set_master net/core/rtnetlink.c:2707 [inline]
 do_setlink+0xe58/0x41c0 net/core/rtnetlink.c:2913
 rtnl_setlink+0x40d/0x5a0 net/core/rtnetlink.c:3209
 rtnetlink_rcv_msg+0x885/0x1040 net/core/rtnetlink.c:6617
 netlink_rcv_skb+0x1e3/0x430 net/netlink/af_netlink.c:2543
 netlink_unicast_kernel net/netlink/af_netlink.c:1341 [inline]
 netlink_unicast+0x7ea/0x980 net/netlink/af_netlink.c:1367
 netlink_sendmsg+0xa3b/0xd70 net/netlink/af_netlink.c:1908
 sock_sendmsg_nosec net/socket.c:730 [inline]
 __sock_sendmsg+0x221/0x270 net/socket.c:745
 sock_write_iter+0x2dd/0x400 net/socket.c:1160
 do_iter_readv_writev+0x46c/0x640
 vfs_writev+0x395/0xbb0 fs/read_write.c:971
 do_writev+0x1b1/0x350 fs/read_write.c:1018
 do_syscall_64+0xf9/0x240
 entry_SYSCALL_64_after_hwframe+0x6f/0x77
RIP: 0033:0x7f19b167dda9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 e1 20 00 00 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 73 01 c3 48 c7 c1 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f19b247f0c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000014
RAX: ffffffffffffffda RBX: 00007f19b17abf80 RCX: 00007f19b167dda9
RDX: 0000000000000001 RSI: 0000000020000040 RDI: 0000000000000004
RBP: 00007f19b16ca47a R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000000b R14: 00007f19b17abf80 R15: 00007ffdad2a3d88
 </TASK>


Tested on:

commit:         67be068d Merge tag 'vfs-6.8-release.fixes' of git://gi..
git tree:       https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
console output: https://syzkaller.appspot.com/x/log.txt?x=16f71336180000
kernel config:  https://syzkaller.appspot.com/x/.config?x=c11c5c676adb61f0
dashboard link: https://syzkaller.appspot.com/bug?extid=3c47b5843403a45aef57
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
patch:          https://syzkaller.appspot.com/x/patch.diff?x=15998cea180000