======================================================
WARNING: possible circular locking dependency detected
6.12.0-rc1-syzkaller-g2d8bce6e34be #0 Not tainted
------------------------------------------------------
syz.3.872/10002 is trying to acquire lock:
ffff8000928827e8 (rfcomm_mutex){+.+.}-{3:3}, at: rfcomm_dlc_exists+0xb0/0x32c net/bluetooth/rfcomm/core.c:546

but task is already holding lock:
ffff8000928861a8 (rfcomm_ioctl_mutex){+.+.}-{3:3}, at: rfcomm_create_dev net/bluetooth/rfcomm/tty.c:484 [inline]
ffff8000928861a8 (rfcomm_ioctl_mutex){+.+.}-{3:3}, at: rfcomm_dev_ioctl+0x25c/0x231c net/bluetooth/rfcomm/tty.c:584

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+0x190/0x21a0 kernel/locking/mutex.c:608
       __mutex_lock kernel/locking/mutex.c:752 [inline]
       mutex_lock_nested+0x2c/0x38 kernel/locking/mutex.c:804
       rfcomm_create_dev net/bluetooth/rfcomm/tty.c:484 [inline]
       rfcomm_dev_ioctl+0x25c/0x231c net/bluetooth/rfcomm/tty.c:584
       rfcomm_sock_ioctl+0x98/0xf0 net/bluetooth/rfcomm/sock.c:869
       sock_do_ioctl+0x134/0x2d0 net/socket.c:1227
       sock_ioctl+0x4ec/0x838 net/socket.c:1346
       vfs_ioctl fs/ioctl.c:51 [inline]
       __do_sys_ioctl fs/ioctl.c:907 [inline]
       __se_sys_ioctl fs/ioctl.c:893 [inline]
       __arm64_sys_ioctl+0x14c/0x1c8 fs/ioctl.c:893
       __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
       invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:49
       el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:132
       do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151
       el0_svc+0x54/0x168 arch/arm64/kernel/entry-common.c:732
       el0t_64_sync_handler+0x84/0x108 arch/arm64/kernel/entry-common.c:750
       el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:598

-> #2 (sk_lock-AF_BLUETOOTH-BTPROTO_RFCOMM){+.+.}-{0:0}:
       lock_sock_nested+0x5c/0x11c net/core/sock.c:3611
       lock_sock include/net/sock.h:1609 [inline]
       rfcomm_sk_state_change+0x60/0x2c8 net/bluetooth/rfcomm/sock.c:73
       __rfcomm_dlc_close+0x234/0x608 net/bluetooth/rfcomm/core.c:493
       rfcomm_dlc_close+0x100/0x194 net/bluetooth/rfcomm/core.c:524
       __rfcomm_sock_close+0x138/0x258 net/bluetooth/rfcomm/sock.c:220
       rfcomm_sock_shutdown+0xa8/0x214 net/bluetooth/rfcomm/sock.c:901
       rfcomm_sock_release+0x58/0x114 net/bluetooth/rfcomm/sock.c:922
       __sock_release net/socket.c:658 [inline]
       sock_close+0xa4/0x1e8 net/socket.c:1426
       __fput+0x1bc/0x75c fs/file_table.c:431
       ____fput+0x20/0x30 fs/file_table.c:459
       task_work_run+0x230/0x2e0 kernel/task_work.c:228
       get_signal+0x1350/0x152c kernel/signal.c:2690
       do_signal+0x26c/0x4c44 arch/arm64/kernel/signal.c:1587
       do_notify_resume+0x74/0x1f4 arch/arm64/kernel/entry-common.c:148
       exit_to_user_mode_prepare arch/arm64/kernel/entry-common.c:169 [inline]
       exit_to_user_mode arch/arm64/kernel/entry-common.c:178 [inline]
       el0_svc+0xac/0x168 arch/arm64/kernel/entry-common.c:733
       el0t_64_sync_handler+0x84/0x108 arch/arm64/kernel/entry-common.c:750
       el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:598

-> #1 (&d->lock){+.+.}-{3:3}:
       __mutex_lock_common+0x190/0x21a0 kernel/locking/mutex.c:608
       __mutex_lock kernel/locking/mutex.c:752 [inline]
       mutex_lock_nested+0x2c/0x38 kernel/locking/mutex.c:804
       __rfcomm_dlc_close+0x1f8/0x608 net/bluetooth/rfcomm/core.c:491
       rfcomm_dlc_close+0x100/0x194 net/bluetooth/rfcomm/core.c:524
       __rfcomm_sock_close+0x138/0x258 net/bluetooth/rfcomm/sock.c:220
       rfcomm_sock_shutdown+0xa8/0x214 net/bluetooth/rfcomm/sock.c:901
       rfcomm_sock_release+0x58/0x114 net/bluetooth/rfcomm/sock.c:922
       __sock_release net/socket.c:658 [inline]
       sock_close+0xa4/0x1e8 net/socket.c:1426
       __fput+0x1bc/0x75c fs/file_table.c:431
       ____fput+0x20/0x30 fs/file_table.c:459
       task_work_run+0x230/0x2e0 kernel/task_work.c:228
       get_signal+0x1350/0x152c kernel/signal.c:2690
       do_signal+0x26c/0x4c44 arch/arm64/kernel/signal.c:1587
       do_notify_resume+0x74/0x1f4 arch/arm64/kernel/entry-common.c:148
       exit_to_user_mode_prepare arch/arm64/kernel/entry-common.c:169 [inline]
       exit_to_user_mode arch/arm64/kernel/entry-common.c:178 [inline]
       el0_svc+0xac/0x168 arch/arm64/kernel/entry-common.c:733
       el0t_64_sync_handler+0x84/0x108 arch/arm64/kernel/entry-common.c:750
       el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:598

-> #0 (rfcomm_mutex){+.+.}-{3:3}:
       check_prev_add kernel/locking/lockdep.c:3161 [inline]
       check_prevs_add kernel/locking/lockdep.c:3280 [inline]
       validate_chain kernel/locking/lockdep.c:3904 [inline]
       __lock_acquire+0x33f8/0x77c8 kernel/locking/lockdep.c:5202
       lock_acquire+0x240/0x728 kernel/locking/lockdep.c:5825
       __mutex_lock_common+0x190/0x21a0 kernel/locking/mutex.c:608
       __mutex_lock kernel/locking/mutex.c:752 [inline]
       mutex_lock_nested+0x2c/0x38 kernel/locking/mutex.c:804
       rfcomm_dlc_exists+0xb0/0x32c 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+0xd64/0x231c net/bluetooth/rfcomm/tty.c:584
       rfcomm_sock_ioctl+0x98/0xf0 net/bluetooth/rfcomm/sock.c:869
       sock_do_ioctl+0x134/0x2d0 net/socket.c:1227
       sock_ioctl+0x4ec/0x838 net/socket.c:1346
       vfs_ioctl fs/ioctl.c:51 [inline]
       __do_sys_ioctl fs/ioctl.c:907 [inline]
       __se_sys_ioctl fs/ioctl.c:893 [inline]
       __arm64_sys_ioctl+0x14c/0x1c8 fs/ioctl.c:893
       __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
       invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:49
       el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:132
       do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151
       el0_svc+0x54/0x168 arch/arm64/kernel/entry-common.c:732
       el0t_64_sync_handler+0x84/0x108 arch/arm64/kernel/entry-common.c:750
       el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:598

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.3.872/10002:
 #0: ffff0000cff8d258 (sk_lock-AF_BLUETOOTH-BTPROTO_RFCOMM){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1609 [inline]
 #0: ffff0000cff8d258 (sk_lock-AF_BLUETOOTH-BTPROTO_RFCOMM){+.+.}-{0:0}, at: rfcomm_sock_ioctl+0x88/0xf0 net/bluetooth/rfcomm/sock.c:868
 #1: ffff8000928861a8 (rfcomm_ioctl_mutex){+.+.}-{3:3}, at: rfcomm_create_dev net/bluetooth/rfcomm/tty.c:484 [inline]
 #1: ffff8000928861a8 (rfcomm_ioctl_mutex){+.+.}-{3:3}, at: rfcomm_dev_ioctl+0x25c/0x231c net/bluetooth/rfcomm/tty.c:584

stack backtrace:
CPU: 1 UID: 0 PID: 10002 Comm: syz.3.872 Not tainted 6.12.0-rc1-syzkaller-g2d8bce6e34be #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/06/2024
Call trace:
 dump_backtrace+0x1b8/0x1e4 arch/arm64/kernel/stacktrace.c:319
 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:326
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0xe4/0x150 lib/dump_stack.c:120
 dump_stack+0x1c/0x28 lib/dump_stack.c:129
 print_circular_bug+0x154/0x1c0 kernel/locking/lockdep.c:2074
 check_noncircular+0x310/0x404 kernel/locking/lockdep.c:2206
 check_prev_add kernel/locking/lockdep.c:3161 [inline]
 check_prevs_add kernel/locking/lockdep.c:3280 [inline]
 validate_chain kernel/locking/lockdep.c:3904 [inline]
 __lock_acquire+0x33f8/0x77c8 kernel/locking/lockdep.c:5202
 lock_acquire+0x240/0x728 kernel/locking/lockdep.c:5825
 __mutex_lock_common+0x190/0x21a0 kernel/locking/mutex.c:608
 __mutex_lock kernel/locking/mutex.c:752 [inline]
 mutex_lock_nested+0x2c/0x38 kernel/locking/mutex.c:804
 rfcomm_dlc_exists+0xb0/0x32c 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+0xd64/0x231c net/bluetooth/rfcomm/tty.c:584
 rfcomm_sock_ioctl+0x98/0xf0 net/bluetooth/rfcomm/sock.c:869
 sock_do_ioctl+0x134/0x2d0 net/socket.c:1227
 sock_ioctl+0x4ec/0x838 net/socket.c:1346
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:907 [inline]
 __se_sys_ioctl fs/ioctl.c:893 [inline]
 __arm64_sys_ioctl+0x14c/0x1c8 fs/ioctl.c:893
 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
 invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:49
 el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:132
 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151
 el0_svc+0x54/0x168 arch/arm64/kernel/entry-common.c:732
 el0t_64_sync_handler+0x84/0x108 arch/arm64/kernel/entry-common.c:750
 el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:598