syzbot

======================================================
WARNING: possible circular locking dependency detected
6.1.66-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor162/3541 is trying to acquire lock:
ffff88807d390dc0 ((work_completion)(&hdev->tx_work)){+.+.}-{0:0}, at: __flush_work+0xe5/0xad0 kernel/workqueue.c:3072

but task is already holding lock:
ffff88807d3910b8 (&hdev->req_lock){+.+.}-{3:3}, at: hci_dev_do_close net/bluetooth/hci_core.c:552 [inline]
ffff88807d3910b8 (&hdev->req_lock){+.+.}-{3:3}, at: hci_rfkill_set_block+0x129/0x200 net/bluetooth/hci_core.c:956

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #3 (&hdev->req_lock){+.+.}-{3:3}:
       lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5662
       __mutex_lock_common kernel/locking/mutex.c:603 [inline]
       __mutex_lock+0x132/0xd80 kernel/locking/mutex.c:747
       hci_dev_do_close net/bluetooth/hci_core.c:552 [inline]
       hci_rfkill_set_block+0x129/0x200 net/bluetooth/hci_core.c:956
       rfkill_set_block+0x1e7/0x430 net/rfkill/core.c:345
       rfkill_fop_write+0x5b7/0x790 net/rfkill/core.c:1286
       vfs_write+0x2d9/0xba0 fs/read_write.c:582
       ksys_write+0x19c/0x2c0 fs/read_write.c:637
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x63/0xcd

-> #2 (rfkill_global_mutex){+.+.}-{3:3}:
       lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5662
       __mutex_lock_common kernel/locking/mutex.c:603 [inline]
       __mutex_lock+0x132/0xd80 kernel/locking/mutex.c:747
       rfkill_register+0x30/0x880 net/rfkill/core.c:1057
       hci_register_dev+0x4df/0xa40 net/bluetooth/hci_core.c:2655
       __vhci_create_device drivers/bluetooth/hci_vhci.c:339 [inline]
       vhci_create_device+0x3ba/0x6f0 drivers/bluetooth/hci_vhci.c:377
       vhci_get_user drivers/bluetooth/hci_vhci.c:434 [inline]
       vhci_write+0x38b/0x440 drivers/bluetooth/hci_vhci.c:514
       call_write_iter include/linux/fs.h:2248 [inline]
       new_sync_write fs/read_write.c:491 [inline]
       vfs_write+0x7ae/0xba0 fs/read_write.c:584
       ksys_write+0x19c/0x2c0 fs/read_write.c:637
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x63/0xcd

-> #1 (&data->open_mutex){+.+.}-{3:3}:
       lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5662
       __mutex_lock_common kernel/locking/mutex.c:603 [inline]
       __mutex_lock+0x132/0xd80 kernel/locking/mutex.c:747
       vhci_send_frame+0x8a/0xf0 drivers/bluetooth/hci_vhci.c:78
       hci_send_frame+0x1ef/0x370 net/bluetooth/hci_core.c:3035
       hci_sched_acl_pkt net/bluetooth/hci_core.c:3642 [inline]
       hci_sched_acl net/bluetooth/hci_core.c:3727 [inline]
       hci_tx_work+0xec8/0x1ec0 net/bluetooth/hci_core.c:3826
       process_one_work+0x8a9/0x11d0 kernel/workqueue.c:2292
       worker_thread+0xa47/0x1200 kernel/workqueue.c:2439
       kthread+0x28d/0x320 kernel/kthread.c:376
       ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306

-> #0 ((work_completion)(&hdev->tx_work)){+.+.}-{0:0}:
       check_prev_add kernel/locking/lockdep.c:3090 [inline]
       check_prevs_add kernel/locking/lockdep.c:3209 [inline]
       validate_chain+0x1661/0x5950 kernel/locking/lockdep.c:3825
       __lock_acquire+0x125b/0x1f80 kernel/locking/lockdep.c:5049
       lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5662
       __flush_work+0xfe/0xad0 kernel/workqueue.c:3072
       hci_dev_close_sync+0x233/0xfc0 net/bluetooth/hci_sync.c:4936
       hci_dev_do_close net/bluetooth/hci_core.c:554 [inline]
       hci_rfkill_set_block+0x131/0x200 net/bluetooth/hci_core.c:956
       rfkill_set_block+0x1e7/0x430 net/rfkill/core.c:345
       rfkill_fop_write+0x5b7/0x790 net/rfkill/core.c:1286
       vfs_write+0x2d9/0xba0 fs/read_write.c:582
       ksys_write+0x19c/0x2c0 fs/read_write.c:637
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x63/0xcd

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-executor162/3541:
 #0: ffffffff8e544aa8 (rfkill_global_mutex){+.+.}-{3:3}, at: rfkill_fop_write+0x1a5/0x790 net/rfkill/core.c:1278
 #1: ffff88807d3910b8 (&hdev->req_lock){+.+.}-{3:3}, at: hci_dev_do_close net/bluetooth/hci_core.c:552 [inline]
 #1: ffff88807d3910b8 (&hdev->req_lock){+.+.}-{3:3}, at: hci_rfkill_set_block+0x129/0x200 net/bluetooth/hci_core.c:956

stack backtrace:
CPU: 1 PID: 3541 Comm: syz-executor162 Not tainted 6.1.66-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/10/2023
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1e3/0x2cb lib/dump_stack.c:106
 check_noncircular+0x2fa/0x3b0 kernel/locking/lockdep.c:2170
 check_prev_add kernel/locking/lockdep.c:3090 [inline]
 check_prevs_add kernel/locking/lockdep.c:3209 [inline]
 validate_chain+0x1661/0x5950 kernel/locking/lockdep.c:3825
 __lock_acquire+0x125b/0x1f80 kernel/locking/lockdep.c:5049
 lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5662
 __flush_work+0xfe/0xad0 kernel/workqueue.c:3072
 hci_dev_close_sync+0x233/0xfc0 net/bluetooth/hci_sync.c:4936
 hci_dev_do_close net/bluetooth/hci_core.c:554 [inline]
 hci_rfkill_set_block+0x131/0x200 net/bluetooth/hci_core.c:956
 rfkill_set_block+0x1e7/0x430 net/rfkill/core.c:345
 rfkill_fop_write+0x5b7/0x790 net/rfkill/core.c:1286
 vfs_write+0x2d9/0xba0 fs/read_write.c:582
 ksys_write+0x19c/0x2c0 fs/read_write.c:637
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f61a9bcc4b9
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:00007fffa363e038 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f61a9c23043 RCX: 000