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Message-ID: <3476064a-e484-29c5-3aa5-6871e1904042@gmail.com>
Date:   Thu, 14 Sep 2023 21:49:38 +0900
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Subject: Re: [syzbot] possible deadlock in team_del_slave (2)
To:     syzbot <syzbot+1c71587a1a09de7fbde3@syzkaller.appspotmail.com>,
        davem@davemloft.net, edumazet@google.com, jiri@resnulli.us,
        kuba@kernel.org, linux-kernel@vger.kernel.org,
        netdev@vger.kernel.org, pabeni@redhat.com,
        syzkaller-bugs@googlegroups.com
References: <00000000000008229305f374404a@google.com>
From:   Taehee Yoo <ap420073@gmail.com>
In-Reply-To: <00000000000008229305f374404a@google.com>
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On 2023. 1. 30. 오후 2:11, syzbot wrote:

Hi,

 > Hello,
 >
 > syzbot found the following issue on:
 >
 > HEAD commit:    83abd4d4c4be Merge tag 'platform-drivers-x86-v6.2-3' 
of gi..
 > git tree:       upstream
 > console output: https://syzkaller.appspot.com/x/log.txt?x=1169c315480000
 > kernel config: 
https://syzkaller.appspot.com/x/.config?x=1adb0905dddc79ba
 > dashboard link: 
https://syzkaller.appspot.com/bug?extid=1c71587a1a09de7fbde3
 > compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU 
Binutils for Debian) 2.35.2
 >
 > Unfortunately, I don't have any reproducer for this issue yet.
 >
 > Downloadable assets:
 > disk image: 
https://storage.googleapis.com/syzbot-assets/27a2378a1d32/disk-83abd4d4.raw.xz
 > vmlinux: 
https://storage.googleapis.com/syzbot-assets/311b7677d1f2/vmlinux-83abd4d4.xz
 > kernel image: 
https://storage.googleapis.com/syzbot-assets/eac6c271be29/bzImage-83abd4d4.xz
 >
 > IMPORTANT: if you fix the issue, please add the following tag to the 
commit:
 > Reported-by: syzbot+1c71587a1a09de7fbde3@syzkaller.appspotmail.com
 >
 > ======================================================
 > WARNING: possible circular locking dependency detected
 > 6.2.0-rc5-syzkaller-00108-g83abd4d4c4be #0 Not tainted
 > ------------------------------------------------------
 > syz-executor.5/19937 is trying to acquire lock:
 > ffff88801ed2ecf8 (team->team_lock_key#2){+.+.}-{3:3}, at: 
team_del_slave+0x31/0x1c0 drivers/net/team/team.c:1998
 >
 > but task is already holding lock:
 > ffff888036730728 (&rdev->wiphy.mtx){+.+.}-{3:3}, at: 
nl80211_del_interface+0xfb/0x190 net/wireless/nl80211.c:4328
 >
 > which lock already depends on the new lock.
 >
 >
 > the existing dependency chain (in reverse order) is:
 >
 > -> #1 (&rdev->wiphy.mtx){+.+.}-{3:3}:
 >         __mutex_lock_common kernel/locking/mutex.c:603 [inline]
 >         __mutex_lock+0x12f/0x1360 kernel/locking/mutex.c:747
 >         wiphy_lock include/net/cfg80211.h:5633 [inline]
 >         ieee80211_open net/mac80211/iface.c:437 [inline]
 >         ieee80211_open+0x193/0x250 net/mac80211/iface.c:424
 >         __dev_open+0x297/0x4d0 net/core/dev.c:1417
 >         dev_open net/core/dev.c:1453 [inline]
 >         dev_open+0xec/0x150 net/core/dev.c:1446
 >         team_port_add drivers/net/team/team.c:1215 [inline]
 >         team_add_slave+0xa03/0x1c70 drivers/net/team/team.c:1984
 >         do_set_master+0x1c8/0x220 net/core/rtnetlink.c:2617
 >         do_setlink+0x89b/0x3bb0 net/core/rtnetlink.c:2820
 >         __rtnl_newlink+0xd69/0x1840 net/core/rtnetlink.c:3590
 >         rtnl_newlink+0x68/0xa0 net/core/rtnetlink.c:3637
 >         rtnetlink_rcv_msg+0x43e/0xca0 net/core/rtnetlink.c:6141
 >         netlink_rcv_skb+0x165/0x440 net/netlink/af_netlink.c:2574
 >         netlink_unicast_kernel net/netlink/af_netlink.c:1339 [inline]
 >         netlink_unicast+0x547/0x7f0 net/netlink/af_netlink.c:1365
 >         netlink_sendmsg+0x91b/0xe10 net/netlink/af_netlink.c:1942
 >         sock_sendmsg_nosec net/socket.c:714 [inline]
 >         sock_sendmsg+0xd3/0x120 net/socket.c:734
 >         ____sys_sendmsg+0x712/0x8c0 net/socket.c:2476
 >         ___sys_sendmsg+0x110/0x1b0 net/socket.c:2530
 >         __sys_sendmsg+0xf7/0x1c0 net/socket.c:2559
 >         do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 >         do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
 >         entry_SYSCALL_64_after_hwframe+0x63/0xcd
 >
 > -> #0 (team->team_lock_key#2){+.+.}-{3:3}:
 >         check_prev_add kernel/locking/lockdep.c:3097 [inline]
 >         check_prevs_add kernel/locking/lockdep.c:3216 [inline]
 >         validate_chain kernel/locking/lockdep.c:3831 [inline]
 >         __lock_acquire+0x2a43/0x56d0 kernel/locking/lockdep.c:5055
 >         lock_acquire kernel/locking/lockdep.c:5668 [inline]
 >         lock_acquire+0x1e3/0x630 kernel/locking/lockdep.c:5633
 >         __mutex_lock_common kernel/locking/mutex.c:603 [inline]
 >         __mutex_lock+0x12f/0x1360 kernel/locking/mutex.c:747
 >         team_del_slave+0x31/0x1c0 drivers/net/team/team.c:1998
 >         team_device_event+0xd7/0xad0 drivers/net/team/team.c:3022
 >         notifier_call_chain+0xb5/0x200 kernel/notifier.c:87
 >         call_netdevice_notifiers_info+0xb5/0x130 net/core/dev.c:1944
 >         call_netdevice_notifiers_extack net/core/dev.c:1982 [inline]
 >         call_netdevice_notifiers net/core/dev.c:1996 [inline]
 >         unregister_netdevice_many_notify+0xa2b/0x19e0 
net/core/dev.c:10839
 >         unregister_netdevice_many net/core/dev.c:10895 [inline]
 >         unregister_netdevice_queue+0x2e5/0x3c0 net/core/dev.c:10776
 >         unregister_netdevice include/linux/netdevice.h:3059 [inline]
 >         _cfg80211_unregister_wdev+0x64a/0x830 net/wireless/core.c:1157
 >         ieee80211_if_remove+0x1e3/0x390 net/mac80211/iface.c:2228
 >         ieee80211_del_iface+0x16/0x20 net/mac80211/cfg.c:202
 >         rdev_del_virtual_intf net/wireless/rdev-ops.h:62 [inline]
 >         cfg80211_remove_virtual_intf+0x10a/0x3b0 net/wireless/util.c:2497
 >         nl80211_del_interface+0x106/0x190 net/wireless/nl80211.c:4330
 >         genl_family_rcv_msg_doit.isra.0+0x1e6/0x2d0 
net/netlink/genetlink.c:968
 >         genl_family_rcv_msg net/netlink/genetlink.c:1048 [inline]
 >         genl_rcv_msg+0x4ff/0x7e0 net/netlink/genetlink.c:1065
 >         netlink_rcv_skb+0x165/0x440 net/netlink/af_netlink.c:2574
 >         genl_rcv+0x28/0x40 net/netlink/genetlink.c:1076
 >         netlink_unicast_kernel net/netlink/af_netlink.c:1339 [inline]
 >         netlink_unicast+0x547/0x7f0 net/netlink/af_netlink.c:1365
 >         netlink_sendmsg+0x91b/0xe10 net/netlink/af_netlink.c:1942
 >         sock_sendmsg_nosec net/socket.c:714 [inline]
 >         sock_sendmsg+0xd3/0x120 net/socket.c:734
 >         ____sys_sendmsg+0x712/0x8c0 net/socket.c:2476
 >         ___sys_sendmsg+0x110/0x1b0 net/socket.c:2530
 >         __sys_sendmsg+0xf7/0x1c0 net/socket.c:2559
 >         do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 >         do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
 >         entry_SYSCALL_64_after_hwframe+0x63/0xcd
 >
 > other info that might help us debug this:
 >
 >   Possible unsafe locking scenario:
 >
 >         CPU0                    CPU1
 >         ----                    ----
 >    lock(&rdev->wiphy.mtx);
 >                                 lock(team->team_lock_key#2);
 >                                 lock(&rdev->wiphy.mtx);
 >    lock(team->team_lock_key#2);
 >
 >   *** DEADLOCK ***
 >
 > 3 locks held by syz-executor.5/19937:
 >   #0: ffffffff8e14f8d0 (cb_lock){++++}-{3:3}, at: genl_rcv+0x19/0x40 
net/netlink/genetlink.c:1075
 >   #1: ffffffff8e0b4328 (rtnl_mutex){+.+.}-{3:3}, at: 
nl80211_pre_doit+0xb4/0xab0 net/wireless/nl80211.c:16161
 >   #2: ffff888036730728 (&rdev->wiphy.mtx){+.+.}-{3:3}, at: 
nl80211_del_interface+0xfb/0x190 net/wireless/nl80211.c:4328
 >
 > stack backtrace:
 > CPU: 0 PID: 19937 Comm: syz-executor.5 Not tainted 
6.2.0-rc5-syzkaller-00108-g83abd4d4c4be #0
 > Hardware name: Google Google Compute Engine/Google Compute Engine, 
BIOS Google 01/12/2023
 > Call Trace:
 >   <TASK>
 >   __dump_stack lib/dump_stack.c:88 [inline]
 >   dump_stack_lvl+0xd1/0x138 lib/dump_stack.c:106
 >   check_noncircular+0x25f/0x2e0 kernel/locking/lockdep.c:2177
 >   check_prev_add kernel/locking/lockdep.c:3097 [inline]
 >   check_prevs_add kernel/locking/lockdep.c:3216 [inline]
 >   validate_chain kernel/locking/lockdep.c:3831 [inline]
 >   __lock_acquire+0x2a43/0x56d0 kernel/locking/lockdep.c:5055
 >   lock_acquire kernel/locking/lockdep.c:5668 [inline]
 >   lock_acquire+0x1e3/0x630 kernel/locking/lockdep.c:5633
 >   __mutex_lock_common kernel/locking/mutex.c:603 [inline]
 >   __mutex_lock+0x12f/0x1360 kernel/locking/mutex.c:747
 >   team_del_slave+0x31/0x1c0 drivers/net/team/team.c:1998
 >   team_device_event+0xd7/0xad0 drivers/net/team/team.c:3022
 >   notifier_call_chain+0xb5/0x200 kernel/notifier.c:87
 >   call_netdevice_notifiers_info+0xb5/0x130 net/core/dev.c:1944
 >   call_netdevice_notifiers_extack net/core/dev.c:1982 [inline]
 >   call_netdevice_notifiers net/core/dev.c:1996 [inline]
 >   unregister_netdevice_many_notify+0xa2b/0x19e0 net/core/dev.c:10839
 >   unregister_netdevice_many net/core/dev.c:10895 [inline]
 >   unregister_netdevice_queue+0x2e5/0x3c0 net/core/dev.c:10776
 >   unregister_netdevice include/linux/netdevice.h:3059 [inline]
 >   _cfg80211_unregister_wdev+0x64a/0x830 net/wireless/core.c:1157
 >   ieee80211_if_remove+0x1e3/0x390 net/mac80211/iface.c:2228
 >   ieee80211_del_iface+0x16/0x20 net/mac80211/cfg.c:202
 >   rdev_del_virtual_intf net/wireless/rdev-ops.h:62 [inline]
 >   cfg80211_remove_virtual_intf+0x10a/0x3b0 net/wireless/util.c:2497
 >   nl80211_del_interface+0x106/0x190 net/wireless/nl80211.c:4330
 >   genl_family_rcv_msg_doit.isra.0+0x1e6/0x2d0 net/netlink/genetlink.c:968
 >   genl_family_rcv_msg net/netlink/genetlink.c:1048 [inline]
 >   genl_rcv_msg+0x4ff/0x7e0 net/netlink/genetlink.c:1065
 >   netlink_rcv_skb+0x165/0x440 net/netlink/af_netlink.c:2574
 >   genl_rcv+0x28/0x40 net/netlink/genetlink.c:1076
 >   netlink_unicast_kernel net/netlink/af_netlink.c:1339 [inline]
 >   netlink_unicast+0x547/0x7f0 net/netlink/af_netlink.c:1365
 >   netlink_sendmsg+0x91b/0xe10 net/netlink/af_netlink.c:1942
 >   sock_sendmsg_nosec net/socket.c:714 [inline]
 >   sock_sendmsg+0xd3/0x120 net/socket.c:734
 >   ____sys_sendmsg+0x712/0x8c0 net/socket.c:2476
 >   ___sys_sendmsg+0x110/0x1b0 net/socket.c:2530
 >   __sys_sendmsg+0xf7/0x1c0 net/socket.c:2559
 >   do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 >   do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
 >   entry_SYSCALL_64_after_hwframe+0x63/0xcd
 > RIP: 0033:0x7fbab9c8c0c9
 > Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 f1 19 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 b8 ff ff ff f7 d8 64 89 01 48
 > RSP: 002b:00007fbaba92a168 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
 > RAX: ffffffffffffffda RBX: 00007fbab9dabf80 RCX: 00007fbab9c8c0c9
 > RDX: 0000000000000000 RSI: 0000000020001000 RDI: 0000000000000004
 > RBP: 00007fbab9ce7ae9 R08: 0000000000000000 R09: 0000000000000000
 > R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
 > R13: 00007ffff9cf40df R14: 00007fbaba92a300 R15: 0000000000022000
 >   </TASK>
 > team0: Port device wlan0 removed

I found a reproducer:
    modprobe mac80211_hwsim
    ip link add team0 type team
    ip link set wlan0 master team0
    ip link set wlan1 master team0
    modprobe -rv mac80211_hwsim

I'm going to send a patch[1], which removes team->lock completely.
This issue will disappear.

[1] https://marc.info/?l=linux-netdev&m=169414027416070&w=2

 >
 >
 > ---
 > This report is generated by a bot. It may contain errors.
 > See https://goo.gl/tpsmEJ for more information about syzbot.
 > syzbot engineers can be reached at syzkaller@googlegroups.com.
 >
 > syzbot will keep track of this issue. See:
 > https://goo.gl/tpsmEJ#status for how to communicate with syzbot.