syzbot

======================================================
WARNING: possible circular locking dependency detected
5.15.157-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor115/3499 is trying to acquire lock:
ffff88807889cb98 ((work_completion)(&hdev->tx_work)){+.+.}-{0:0}, at: __flush_work+0xcf/0x1a0 kernel/workqueue.c:3090

but task is already holding lock:
ffff88807889cff0 (&hdev->req_lock){+.+.}-{3:3}, at: hci_dev_do_close+0x63/0x1070 net/bluetooth/hci_core.c:1737

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #3 (&hdev->req_lock){+.+.}-{3:3}:
       lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5623
       __mutex_lock_common+0x1da/0x25a0 kernel/locking/mutex.c:596
       __mutex_lock kernel/locking/mutex.c:729 [inline]
       mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
       hci_dev_do_close+0x63/0x1070 net/bluetooth/hci_core.c:1737
       hci_rfkill_set_block+0x114/0x1a0 net/bluetooth/hci_core.c:2235
       rfkill_set_block+0x1e7/0x430 net/rfkill/core.c:345
       rfkill_fop_write+0x5b7/0x790 net/rfkill/core.c:1274
       vfs_write+0x30c/0xe50 fs/read_write.c:592
       ksys_write+0x1a2/0x2c0 fs/read_write.c:647
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x66/0xd0

-> #2 (rfkill_global_mutex){+.+.}-{3:3}:
       lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5623
       __mutex_lock_common+0x1da/0x25a0 kernel/locking/mutex.c:596
       __mutex_lock kernel/locking/mutex.c:729 [inline]
       mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
       rfkill_register+0x30/0x880 net/rfkill/core.c:1045
       hci_register_dev+0x4dd/0xa50 net/bluetooth/hci_core.c:3960
       __vhci_create_device drivers/bluetooth/hci_vhci.c:129 [inline]
       vhci_create_device+0x310/0x590 drivers/bluetooth/hci_vhci.c:153
       vhci_get_user drivers/bluetooth/hci_vhci.c:210 [inline]
       vhci_write+0x382/0x430 drivers/bluetooth/hci_vhci.c:290
       call_write_iter include/linux/fs.h:2172 [inline]
       new_sync_write fs/read_write.c:507 [inline]
       vfs_write+0xacf/0xe50 fs/read_write.c:594
       ksys_write+0x1a2/0x2c0 fs/read_write.c:647
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x66/0xd0

-> #1 (&data->open_mutex){+.+.}-{3:3}:
       lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5623
       __mutex_lock_common+0x1da/0x25a0 kernel/locking/mutex.c:596
       __mutex_lock kernel/locking/mutex.c:729 [inline]
       mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
       vhci_send_frame+0x8a/0xf0 drivers/bluetooth/hci_vhci.c:71
       hci_send_frame+0x1af/0x2f0 net/bluetooth/hci_core.c:4252
       hci_sched_acl_pkt net/bluetooth/hci_core.c:4777 [inline]
       hci_sched_acl net/bluetooth/hci_core.c:4862 [inline]
       hci_tx_work+0xb0b/0x19d0 net/bluetooth/hci_core.c:4933
       process_one_work+0x8a1/0x10c0 kernel/workqueue.c:2310
       worker_thread+0xaca/0x1280 kernel/workqueue.c:2457
       kthread+0x3f6/0x4f0 kernel/kthread.c:334
       ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:300

-> #0 ((work_completion)(&hdev->tx_work)){+.+.}-{0:0}:
       check_prev_add kernel/locking/lockdep.c:3053 [inline]
       check_prevs_add kernel/locking/lockdep.c:3172 [inline]
       validate_chain+0x1649/0x5930 kernel/locking/lockdep.c:3788
       __lock_acquire+0x1295/0x1ff0 kernel/locking/lockdep.c:5012
       lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5623
       __flush_work+0xeb/0x1a0 kernel/workqueue.c:3090
       hci_dev_do_close+0x20a/0x1070 net/bluetooth/hci_core.c:1756
       hci_rfkill_set_block+0x114/0x1a0 net/bluetooth/hci_core.c:2235
       rfkill_set_block+0x1e7/0x430 net/rfkill/core.c:345
       rfkill_fop_write+0x5b7/0x790 net/rfkill/core.c:1274
       vfs_write+0x30c/0xe50 fs/read_write.c:592
       ksys_write+0x1a2/0x2c0 fs/read_write.c:647
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x66/0xd0

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-executor115/3499:
 #0: ffffffff8dc73388 (rfkill_global_mutex){+.+.}-{3:3}, at: rfkill_fop_write+0x1a5/0x790 net/rfkill/core.c:1266
 #1: ffff88807889cff0 (&hdev->req_lock){+.+.}-{3:3}, at: hci_dev_do_close+0x63/0x1070 net/bluetooth/hci_core.c:1737

stack backtrace:
CPU: 1 PID: 3499 Comm: syz-executor115 Not tainted 5.15.157-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1e3/0x2d0 lib/dump_stack.c:106
 check_noncircular+0x2f8/0x3b0 kernel/locking/lockdep.c:2133
 check_prev_add kernel/locking/lockdep.c:3053 [inline]
 check_prevs_add kernel/locking/lockdep.c:3172 [inline]
 validate_chain+0x1649/0x5930 kernel/locking/lockdep.c:3788
 __lock_acquire+0x1295/0x1ff0 kernel/locking/lockdep.c:5012
 lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5623
 __flush_work+0xeb/0x1a0 kernel/workqueue.c:3090
 hci_dev_do_close+0x20a/0x1070 net/bluetooth/hci_core.c:1756
 hci_rfkill_set_block+0x114/0x1a0 net/bluetooth/hci_core.c:2235
 rfkill_set_block+0x1e7/0x430 net/rfkill/core.c:345
 rfkill_fop_write+0x5b7/0x790 net/rfkill/core.c:1274
 vfs_write+0x30c/0xe50 fs/read_write.c:592
 ksys_write+0x1a2/0x2c0 fs/read_write.c:647
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f491fed74b9
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:00007ffe46432408 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f491ff2e043 RCX: 00007f491fed74b9
RDX: 0000000000000008 RSI: 0000000020000080 RDI: 0000000000000003
RBP: 00007ffe46432450 R08: 000000ff00ff0650 R09: 000000ff00ff0650
R10: 0000000000000000 R11: 000000000000024