syzbot

======================================================
WARNING: possible circular locking dependency detected
6.6.0-rc6-syzkaller-00029-g213f891525c2 #0 Not tainted
------------------------------------------------------
syz-executor415/5062 is trying to acquire lock:
ffffffff8e880088 (rfcomm_mutex){+.+.}-{3:3}, at: rfcomm_dlc_exists+0x5b/0x190 net/bluetooth/rfcomm/core.c:546

but task is already holding lock:
ffffffff8e885008 (rfcomm_ioctl_mutex){+.+.}-{3:3}, at: rfcomm_create_dev net/bluetooth/rfcomm/tty.c:484 [inline]
ffffffff8e885008 (rfcomm_ioctl_mutex){+.+.}-{3:3}, at: rfcomm_dev_ioctl+0x8b9/0x1c50 net/bluetooth/rfcomm/tty.c:587

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #3 (rfcomm_ioctl_mutex){+.+.}-{3:3}:
       __mutex_lock_common kernel/locking/mutex.c:603 [inline]
       __mutex_lock+0x181/0x1340 kernel/locking/mutex.c:747
       rfcomm_create_dev net/bluetooth/rfcomm/tty.c:484 [inline]
       rfcomm_dev_ioctl+0x8b9/0x1c50 net/bluetooth/rfcomm/tty.c:587
       rfcomm_sock_ioctl+0xb0/0xe0 net/bluetooth/rfcomm/sock.c:873
       sock_do_ioctl+0x113/0x270 net/socket.c:1220
       sock_ioctl+0x229/0x6b0 net/socket.c:1339
       vfs_ioctl fs/ioctl.c:51 [inline]
       __do_sys_ioctl fs/ioctl.c:871 [inline]
       __se_sys_ioctl fs/ioctl.c:857 [inline]
       __x64_sys_ioctl+0x18f/0x210 fs/ioctl.c:857
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x38/0xb0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x63/0xcd

-> #2 (sk_lock-AF_BLUETOOTH-BTPROTO_RFCOMM){+.+.}-{0:0}:
       lock_sock_nested+0x3a/0xf0 net/core/sock.c:3505
       lock_sock include/net/sock.h:1722 [inline]
       rfcomm_sk_state_change+0x6d/0x3a0 net/bluetooth/rfcomm/sock.c:73
       __rfcomm_dlc_close+0x285/0x720 net/bluetooth/rfcomm/core.c:493
       rfcomm_dlc_close+0x1e7/0x240 net/bluetooth/rfcomm/core.c:524
       __rfcomm_sock_close+0xa7/0x230 net/bluetooth/rfcomm/sock.c:220
       rfcomm_sock_shutdown+0xd1/0x230 net/bluetooth/rfcomm/sock.c:905
       rfcomm_sock_release+0x5d/0x140 net/bluetooth/rfcomm/sock.c:926
       __sock_release+0xae/0x260 net/socket.c:659
       sock_close+0x1c/0x20 net/socket.c:1419
       __fput+0x3f7/0xa70 fs/file_table.c:384
       task_work_run+0x14d/0x240 kernel/task_work.c:180
       exit_task_work include/linux/task_work.h:38 [inline]
       do_exit+0xa92/0x2a20 kernel/exit.c:874
       do_group_exit+0xd4/0x2a0 kernel/exit.c:1024
       get_signal+0x23ba/0x2790 kernel/signal.c:2892
       arch_do_signal_or_restart+0x90/0x7f0 arch/x86/kernel/signal.c:309
       exit_to_user_mode_loop kernel/entry/common.c:168 [inline]
       exit_to_user_mode_prepare+0x11f/0x240 kernel/entry/common.c:204
       __syscall_exit_to_user_mode_work kernel/entry/common.c:285 [inline]
       syscall_exit_to_user_mode+0x1d/0x60 kernel/entry/common.c:296
       do_syscall_64+0x44/0xb0 arch/x86/entry/common.c:86
       entry_SYSCALL_64_after_hwframe+0x63/0xcd

-> #1 (&d->lock){+.+.}-{3:3}:
       __mutex_lock_common kernel/locking/mutex.c:603 [inline]
       __mutex_lock+0x181/0x1340 kernel/locking/mutex.c:747
       __rfcomm_dlc_close+0x231/0x720 net/bluetooth/rfcomm/core.c:491
       rfcomm_dlc_close+0x1e7/0x240 net/bluetooth/rfcomm/core.c:524
       __rfcomm_sock_close+0xa7/0x230 net/bluetooth/rfcomm/sock.c:220
       rfcomm_sock_shutdown+0xd1/0x230 net/bluetooth/rfcomm/sock.c:905
       rfcomm_sock_release+0x5d/0x140 net/bluetooth/rfcomm/sock.c:926
       __sock_release+0xae/0x260 net/socket.c:659
       sock_close+0x1c/0x20 net/socket.c:1419
       __fput+0x3f7/0xa70 fs/file_table.c:384
       task_work_run+0x14d/0x240 kernel/task_work.c:180
       exit_task_work include/linux/task_work.h:38 [inline]
       do_exit+0xa92/0x2a20 kernel/exit.c:874
       do_group_exit+0xd4/0x2a0 kernel/exit.c:1024
       get_signal+0x23ba/0x2790 kernel/signal.c:2892
       arch_do_signal_or_restart+0x90/0x7f0 arch/x86/kernel/signal.c:309
       exit_to_user_mode_loop kernel/entry/common.c:168 [inline]
       exit_to_user_mode_prepare+0x11f/0x240 kernel/entry/common.c:204
       __syscall_exit_to_user_mode_work kernel/entry/common.c:285 [inline]
       syscall_exit_to_user_mode+0x1d/0x60 kernel/entry/common.c:296
       do_syscall_64+0x44/0xb0 arch/x86/entry/common.c:86
       entry_SYSCALL_64_after_hwframe+0x63/0xcd

-> #0 (rfcomm_mutex){+.+.}-{3:3}:
       check_prev_add kernel/locking/lockdep.c:3134 [inline]
       check_prevs_add kernel/locking/lockdep.c:3253 [inline]
       validate_chain kernel/locking/lockdep.c:3868 [inline]
       __lock_acquire+0x2e3d/0x5de0 kernel/locking/lockdep.c:5136
       lock_acquire kernel/locking/lockdep.c:5753 [inline]
       lock_acquire+0x1ae/0x510 kernel/locking/lockdep.c:5718
       __mutex_lock_common kernel/locking/mutex.c:603 [inline]
       __mutex_lock+0x181/0x1340 kernel/locking/mutex.c:747
       rfcomm_dlc_exists+0x5b/0x190 net/bluetooth/rfcomm/core.c:546
       __rfcomm_create_dev net/bluetooth/rfcomm/tty.c:414 [inline]
       rfcomm_create_dev net/bluetooth/rfcomm/tty.c:485 [inline]
       rfcomm_dev_ioctl+0x999/0x1c50 net/bluetooth/rfcomm/tty.c:587
       rfcomm_sock_ioctl+0xb0/0xe0 net/bluetooth/rfcomm/sock.c:873
       sock_do_ioctl+0x113/0x270 net/socket.c:1220
       sock_ioctl+0x229/0x6b0 net/socket.c:1339
       vfs_ioctl fs/ioctl.c:51 [inline]
       __do_sys_ioctl fs/ioctl.c:871 [inline]
       __se_sys_ioctl fs/ioctl.c:857 [inline]
       __x64_sys_ioctl+0x18f/0x210 fs/ioctl.c:857
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x38/0xb0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x63/0xcd

other info that might help us debug this:

Chain exists of:
  rfcomm_mutex --> sk_lock-AF_BLUETOOTH-BTPROTO_RFCOMM --> rfcomm_ioctl_mutex

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(rfcomm_ioctl_mutex);
                               lock(sk_lock-AF_BLUETOOTH-BTPROTO_RFCOMM);
                               lock(rfcomm_ioctl_mutex);
  lock(rfcomm_mutex);

 *** DEADLOCK ***

2 locks held by syz-executor415/5062:
 #0: ffff8880290d4130 (sk_lock-AF_BLUETOOTH-BTPROTO_RFCOMM){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1722 [inline]
 #0: ffff8880290d4130 (sk_lock-AF_BLUETOOTH-BTPROTO_RFCOMM){+.+.}-{0:0}, at: rfcomm_sock_ioctl+0xa3/0xe0 net/bluetooth/rfcomm/sock.c:872
 #1: ffffffff8e885008 (rfcomm_ioctl_mutex){+.+.}-{3:3}, at: rfcomm_create_dev net/bluetooth/rfcomm/tty.c:484 [inline]
 #1: ffffffff8e885008 (rfcomm_ioctl_mutex){+.+.}-{3:3}, at: rfcomm_dev_ioctl+0x8b9/0x1c50 net/bluetooth/rfcomm/tty.c:587

stack backtrace:
CPU: 0 PID: 5062 Comm: syz-executor415 Not tainted 6.6.0-rc6-syzkaller-00029-g213f891525c2 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/06/2023
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xd9/0x1b0 lib/dump_stack.c:106
 check_noncircular+0x311/0x3f0 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:3868 [inline]
 __lock_acquire+0x2e3d/0x5de0 kernel/locking/lockdep.c:5136
 lock_acquire kernel/locking/lockdep.c:5753 [inline]
 lock_acquire+0x1ae/0x510 kernel/locking/lockdep.c:5718
 __mutex_lock_common kernel/locking/mutex.c:603 [inline]
 __mutex_lock+0x181/0x1340 kernel/locking/mutex.c:747
 rfcomm_dlc_exists+0x5b/0x190 net/bluetooth/rfcomm/core.c:546
 __rfcomm_create_dev net/bluetooth/rfcomm/tty.c:414 [inline]
 rfcomm_create_dev net/bluetooth/rfcomm/tty.c:485 [inline]
 rfcomm_dev_ioctl+0x999/0x1c50 net/bluetooth/rfcomm/tty.c:587
 rfcomm_sock_ioctl+0xb0/0xe0 net/bluetooth/rfcomm/sock.c:873
 sock_do_ioctl+0x113/0x270 net/socket.c:1220
 sock_ioctl+0x229/0x6b0 net/socket.c:1339
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:871 [inline]
 __se_sys_ioctl fs/ioctl.c:857 [inline]
 __x64_sys_ioctl+0x18f/0x210 fs/ioctl.c:857
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x38/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f9e22bc1d09
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 11 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 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffe16448918 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00007f9e22bc1d09
RDX: 0000000020000100 RSI: 00000000400452c8 RDI: 0000000000000005
RBP: 00000000000f4240 R08: 0000000000000000 R09: 0000555500000000
R10: 0000555500000000 R11: 0000000000000246 R12: 00007ffe16448960
R13: 00007ffe16448970 R14: 000000000001ced2 R15: 00007ffe16448930
 </TASK>