syzbot

======================================================
WARNING: possible circular locking dependency detected
6.7.0-rc6-syzkaller-00010-g2cf4f94d8e86 #0 Not tainted
------------------------------------------------------
syz-executor244/5073 is trying to acquire lock:
ffff88807c4c0e10 ((work_completion)(&hdev->tx_work)){+.+.}-{0:0}, at: __flush_work+0xfa/0xa10 kernel/workqueue.c:3400

but task is already holding lock:
ffff88807c4c1108 (&hdev->req_lock){+.+.}-{3:3}, at: hci_dev_do_close+0x26/0x90 net/bluetooth/hci_core.c:552

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #3 (&hdev->req_lock){+.+.}-{3:3}:
       __mutex_lock_common kernel/locking/mutex.c:603 [inline]
       __mutex_lock+0x175/0x9d0 kernel/locking/mutex.c:747
       hci_dev_do_close+0x26/0x90 net/bluetooth/hci_core.c:552
       hci_rfkill_set_block+0x1b9/0x200 net/bluetooth/hci_core.c:956
       rfkill_set_block+0x200/0x550 net/rfkill/core.c:346
       rfkill_fop_write+0x2d4/0x570 net/rfkill/core.c:1305
       vfs_write+0x2a4/0xdf0 fs/read_write.c:582
       ksys_write+0x1f0/0x250 fs/read_write.c:637
       do_syscall_x64 arch/x86/entry/common.c:52 [inline]
       do_syscall_64+0x40/0x110 arch/x86/entry/common.c:83
       entry_SYSCALL_64_after_hwframe+0x63/0x6b

-> #2 (rfkill_global_mutex){+.+.}-{3:3}:
       __mutex_lock_common kernel/locking/mutex.c:603 [inline]
       __mutex_lock+0x175/0x9d0 kernel/locking/mutex.c:747
       rfkill_register+0x3a/0xb30 net/rfkill/core.c:1075
       hci_register_dev+0x43a/0xd40 net/bluetooth/hci_core.c:2658
       __vhci_create_device+0x393/0x800 drivers/bluetooth/hci_vhci.c:437
       vhci_create_device drivers/bluetooth/hci_vhci.c:478 [inline]
       vhci_get_user drivers/bluetooth/hci_vhci.c:535 [inline]
       vhci_write+0x2c7/0x470 drivers/bluetooth/hci_vhci.c:615
       call_write_iter include/linux/fs.h:2020 [inline]
       new_sync_write fs/read_write.c:491 [inline]
       vfs_write+0x64f/0xdf0 fs/read_write.c:584
       ksys_write+0x12f/0x250 fs/read_write.c:637
       do_syscall_x64 arch/x86/entry/common.c:52 [inline]
       do_syscall_64+0x40/0x110 arch/x86/entry/common.c:83
       entry_SYSCALL_64_after_hwframe+0x63/0x6b

-> #1 (&data->open_mutex){+.+.}-{3:3}:
       __mutex_lock_common kernel/locking/mutex.c:603 [inline]
       __mutex_lock+0x175/0x9d0 kernel/locking/mutex.c:747
       vhci_send_frame+0x67/0xa0 drivers/bluetooth/hci_vhci.c:78
       hci_send_frame+0x220/0x470 net/bluetooth/hci_core.c:3042
       hci_sched_acl_pkt net/bluetooth/hci_core.c:3654 [inline]
       hci_sched_acl net/bluetooth/hci_core.c:3739 [inline]
       hci_tx_work+0x1456/0x1e40 net/bluetooth/hci_core.c:3838
       process_one_work+0x886/0x15d0 kernel/workqueue.c:2627
       process_scheduled_works kernel/workqueue.c:2700 [inline]
       worker_thread+0x8b9/0x1290 kernel/workqueue.c:2781
       kthread+0x2c6/0x3a0 kernel/kthread.c:388
       ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
       ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:242

-> #0 ((work_completion)(&hdev->tx_work)){+.+.}-{0:0}:
       check_prev_add kernel/locking/lockdep.c:3134 [inline]
       check_prevs_add kernel/locking/lockdep.c:3253 [inline]
       validate_chain kernel/locking/lockdep.c:3869 [inline]
       __lock_acquire+0x2433/0x3b20 kernel/locking/lockdep.c:5137
       lock_acquire kernel/locking/lockdep.c:5754 [inline]
       lock_acquire+0x1ae/0x520 kernel/locking/lockdep.c:5719
       __flush_work+0x103/0xa10 kernel/workqueue.c:3400
       hci_dev_close_sync+0x22d/0x1160 net/bluetooth/hci_sync.c:4982
       hci_dev_do_close+0x2e/0x90 net/bluetooth/hci_core.c:554
       hci_rfkill_set_block+0x1b9/0x200 net/bluetooth/hci_core.c:956
       rfkill_set_block+0x200/0x550 net/rfkill/core.c:346
       rfkill_fop_write+0x2d4/0x570 net/rfkill/core.c:1305
       vfs_write+0x2a4/0xdf0 fs/read_write.c:582
       ksys_write+0x1f0/0x250 fs/read_write.c:637
       do_syscall_x64 arch/x86/entry/common.c:52 [inline]
       do_syscall_64+0x40/0x110 arch/x86/entry/common.c:83
       entry_SYSCALL_64_after_hwframe+0x63/0x6b

other info that might help us debug this:

Chain exists of:
  (work_completion)(&hdev->tx_work) --> rfkill_global_mutex --> &hdev->req_lock

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&hdev->req_lock);
                               lock(rfkill_global_mutex);
                               lock(&hdev->req_lock);
  lock((work_completion)(&hdev->tx_work));

 *** DEADLOCK ***

2 locks held by syz-executor244/5073:
 #0: ffffffff8ef2caa8 (rfkill_global_mutex){+.+.}-{3:3}, at: rfkill_fop_write+0x16e/0x570 net/rfkill/core.c:1297
 #1: ffff88807c4c1108 (&hdev->req_lock){+.+.}-{3:3}, at: hci_dev_do_close+0x26/0x90 net/bluetooth/hci_core.c:552

stack backtrace:
CPU: 1 PID: 5073 Comm: syz-executor244 Not tainted 6.7.0-rc6-syzkaller-00010-g2cf4f94d8e86 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/17/2023
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xd9/0x1b0 lib/dump_stack.c:106
 check_noncircular+0x317/0x400 kernel/locking/lockdep.c:2187
 check_prev_add kernel/locking/lockdep.c:3134 [inline]
 check_prevs_add kernel/locking/lockdep.c:3253 [inline]
 validate_chain kernel/locking/lockdep.c:3869 [inline]
 __lock_acquire+0x2433/0x3b20 kernel/locking/lockdep.c:5137
 lock_acquire kernel/locking/lockdep.c:5754 [inline]
 lock_acquire+0x1ae/0x520 kernel/locking/lockdep.c:5719
 __flush_work+0x103/0xa10 kernel/workqueue.c:3400
 hci_dev_close_sync+0x22d/0x1160 net/bluetooth/hci_sync.c:4982
 hci_dev_do_close+0x2e/0x90 net/bluetooth/hci_core.c:554
 hci_rfkill_set_block+0x1b9/0x200 net/bluetooth/hci_core.c:956
 rfkill_set_block+0x200/0x550 net/rfkill/core.c:346
 rfkill_fop_write+0x2d4/0x570 net/rfkill/core.c:1305
 vfs_write+0x2a4/0xdf0 fs/read_write.c:582
 ksys_write+0x1f0/0x250 fs/read_write.c:637
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0x40/0x110 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x63/0x6b
RIP: 0033:0x7f9f56d56479
Code: 48 83 c4 28 c3 e8 e7 18 00 00 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 73 01 c3 48 c7 c1 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffebd900428 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f9f56dad043 RCX: 00007f9f56d56479
RDX: 0000000000000008 RSI: 0000000020000000 RDI: 0000000000000003
RBP: 00007ffebd900470 R08: 000000ff00ff0650 R09: 000000ff00ff0650
R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffebd900458
R13: 00007f9f56dda5b0 R14: 0000000000000000 R15: 0000000000000001
 </TASK>