syzbot

======================================================
WARNING: possible circular locking dependency detected
5.15.156-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor281/3988 is trying to acquire lock:
ffff800016b98b68 (rfcomm_mutex){+.+.}-{3:3}, at: rfcomm_dlc_exists+0xb0/0x32c net/bluetooth/rfcomm/core.c:542

but task is already holding lock:
ffff800016b9c4c8 (rfcomm_ioctl_mutex){+.+.}-{3:3}, at: rfcomm_create_dev net/bluetooth/rfcomm/tty.c:485 [inline]
ffff800016b9c4c8 (rfcomm_ioctl_mutex){+.+.}-{3:3}, at: rfcomm_dev_ioctl+0x258/0x2434 net/bluetooth/rfcomm/tty.c:588

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+0x194/0x2154 kernel/locking/mutex.c:596
       __mutex_lock kernel/locking/mutex.c:729 [inline]
       mutex_lock_nested+0xa4/0xf8 kernel/locking/mutex.c:743
       rfcomm_create_dev net/bluetooth/rfcomm/tty.c:485 [inline]
       rfcomm_dev_ioctl+0x258/0x2434 net/bluetooth/rfcomm/tty.c:588
       rfcomm_sock_ioctl+0x98/0xf0 net/bluetooth/rfcomm/sock.c:880
       sock_do_ioctl+0x134/0x2dc net/socket.c:1140
       sock_ioctl+0x4f0/0x8ac net/socket.c:1257
       vfs_ioctl fs/ioctl.c:51 [inline]
       __do_sys_ioctl fs/ioctl.c:874 [inline]
       __se_sys_ioctl fs/ioctl.c:860 [inline]
       __arm64_sys_ioctl+0x14c/0x1c8 fs/ioctl.c:860
       __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
       invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:52
       el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
       do_el0_svc+0x58/0x14c arch/arm64/kernel/syscall.c:181
       el0_svc+0x7c/0x1f0 arch/arm64/kernel/entry-common.c:608
       el0t_64_sync_handler+0x84/0xe4 arch/arm64/kernel/entry-common.c:626
       el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584

-> #2 (sk_lock-AF_BLUETOOTH-BTPROTO_RFCOMM){+.+.}-{0:0}:
       lock_sock_nested+0xec/0x1ec net/core/sock.c:3250
       lock_sock include/net/sock.h:1668 [inline]
       rfcomm_sk_state_change+0x60/0x2c8 net/bluetooth/rfcomm/sock.c:73
       __rfcomm_dlc_close+0x23c/0x634 net/bluetooth/rfcomm/core.c:489
       rfcomm_dlc_close+0x100/0x194 net/bluetooth/rfcomm/core.c:520
       __rfcomm_sock_close+0x138/0x258 net/bluetooth/rfcomm/sock.c:220
       rfcomm_sock_shutdown+0xa8/0x214 net/bluetooth/rfcomm/sock.c:912
       rfcomm_sock_release+0x58/0x114 net/bluetooth/rfcomm/sock.c:933
       __sock_release net/socket.c:649 [inline]
       sock_close+0xb8/0x1fc net/socket.c:1336
       __fput+0x30c/0x7f0 fs/file_table.c:280
       ____fput+0x20/0x30 fs/file_table.c:308
       task_work_run+0x130/0x1e4 kernel/task_work.c:164
       exit_task_work include/linux/task_work.h:32 [inline]
       do_exit+0x670/0x20bc kernel/exit.c:872
       do_group_exit+0x110/0x268 kernel/exit.c:994
       get_signal+0x634/0x1550 kernel/signal.c:2889
       do_signal arch/arm64/kernel/signal.c:890 [inline]
       do_notify_resume+0x3d0/0x32b8 arch/arm64/kernel/signal.c:943
       prepare_exit_to_user_mode arch/arm64/kernel/entry-common.c:133 [inline]
       exit_to_user_mode arch/arm64/kernel/entry-common.c:138 [inline]
       el0_svc+0xfc/0x1f0 arch/arm64/kernel/entry-common.c:609
       el0t_64_sync_handler+0x84/0xe4 arch/arm64/kernel/entry-common.c:626
       el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584

-> #1 (&d->lock){+.+.}-{3:3}:
       __mutex_lock_common+0x194/0x2154 kernel/locking/mutex.c:596
       __mutex_lock kernel/locking/mutex.c:729 [inline]
       mutex_lock_nested+0xa4/0xf8 kernel/locking/mutex.c:743
       __rfcomm_dlc_close+0x200/0x634 net/bluetooth/rfcomm/core.c:487
       rfcomm_dlc_close+0x100/0x194 net/bluetooth/rfcomm/core.c:520
       __rfcomm_sock_close+0x138/0x258 net/bluetooth/rfcomm/sock.c:220
       rfcomm_sock_shutdown+0xa8/0x214 net/bluetooth/rfcomm/sock.c:912
       rfcomm_sock_release+0x58/0x114 net/bluetooth/rfcomm/sock.c:933
       __sock_release net/socket.c:649 [inline]
       sock_close+0xb8/0x1fc net/socket.c:1336
       __fput+0x30c/0x7f0 fs/file_table.c:280
       ____fput+0x20/0x30 fs/file_table.c:308
       task_work_run+0x130/0x1e4 kernel/task_work.c:164
       exit_task_work include/linux/task_work.h:32 [inline]
       do_exit+0x670/0x20bc kernel/exit.c:872
       do_group_exit+0x110/0x268 kernel/exit.c:994
       get_signal+0x634/0x1550 kernel/signal.c:2889
       do_signal arch/arm64/kernel/signal.c:890 [inline]
       do_notify_resume+0x3d0/0x32b8 arch/arm64/kernel/signal.c:943
       prepare_exit_to_user_mode arch/arm64/kernel/entry-common.c:133 [inline]
       exit_to_user_mode arch/arm64/kernel/entry-common.c:138 [inline]
       el0_svc+0xfc/0x1f0 arch/arm64/kernel/entry-common.c:609
       el0t_64_sync_handler+0x84/0xe4 arch/arm64/kernel/entry-common.c:626
       el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584

-> #0 (rfcomm_mutex){+.+.}-{3:3}:
       check_prev_add kernel/locking/lockdep.c:3053 [inline]
       check_prevs_add kernel/locking/lockdep.c:3172 [inline]
       validate_chain kernel/locking/lockdep.c:3788 [inline]
       __lock_acquire+0x32d4/0x7638 kernel/locking/lockdep.c:5012
       lock_acquire+0x240/0x77c kernel/locking/lockdep.c:5623
       __mutex_lock_common+0x194/0x2154 kernel/locking/mutex.c:596
       __mutex_lock kernel/locking/mutex.c:729 [inline]
       mutex_lock_nested+0xa4/0xf8 kernel/locking/mutex.c:743
       rfcomm_dlc_exists+0xb0/0x32c net/bluetooth/rfcomm/core.c:542
       __rfcomm_create_dev net/bluetooth/rfcomm/tty.c:415 [inline]
       rfcomm_create_dev net/bluetooth/rfcomm/tty.c:486 [inline]
       rfcomm_dev_ioctl+0x938/0x2434 net/bluetooth/rfcomm/tty.c:588
       rfcomm_sock_ioctl+0x98/0xf0 net/bluetooth/rfcomm/sock.c:880
       sock_do_ioctl+0x134/0x2dc net/socket.c:1140
       sock_ioctl+0x4f0/0x8ac net/socket.c:1257
       vfs_ioctl fs/ioctl.c:51 [inline]
       __do_sys_ioctl fs/ioctl.c:874 [inline]
       __se_sys_ioctl fs/ioctl.c:860 [inline]
       __arm64_sys_ioctl+0x14c/0x1c8 fs/ioctl.c:860
       __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
       invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:52
       el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
       do_el0_svc+0x58/0x14c arch/arm64/kernel/syscall.c:181
       el0_svc+0x7c/0x1f0 arch/arm64/kernel/entry-common.c:608
       el0t_64_sync_handler+0x84/0xe4 arch/arm64/kernel/entry-common.c:626
       el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584

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-executor281/3988:
 #0: ffff0000dd41b120 (sk_lock-AF_BLUETOOTH-BTPROTO_RFCOMM){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1668 [inline]
 #0: ffff0000dd41b120 (sk_lock-AF_BLUETOOTH-BTPROTO_RFCOMM){+.+.}-{0:0}, at: rfcomm_sock_ioctl+0x88/0xf0 net/bluetooth/rfcomm/sock.c:879
 #1: ffff800016b9c4c8 (rfcomm_ioctl_mutex){+.+.}-{3:3}, at: rfcomm_create_dev net/bluetooth/rfcomm/tty.c:485 [inline]
 #1: ffff800016b9c4c8 (rfcomm_ioctl_mutex){+.+.}-{3:3}, at: rfcomm_dev_ioctl+0x258/0x2434 net/bluetooth/rfcomm/tty.c:588

stack backtrace:
CPU: 0 PID: 3988 Comm: syz-executor281 Not tainted 5.15.156-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
Call trace:
 dump_backtrace+0x0/0x530 arch/arm64/kernel/stacktrace.c:152
 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:216
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x108/0x170 lib/dump_stack.c:106
 dump_stack+0x1c/0x58 lib/dump_stack.c:113
 print_circular_bug+0x150/0x1b8 kernel/locking/lockdep.c:2011
 check_noncircular+0x2cc/0x378 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 kernel/locking/lockdep.c:3788 [inline]
 __lock_acquire+0x32d4/0x7638 kernel/locking/lockdep.c:5012
 lock_acquire+0x240/0x77c kernel/locking/lockdep.c:5623
 __mutex_lock_common+0x194/0x2154 kernel/locking/mutex.c:596
 __mutex_lock kernel/locking/mutex.c:729 [inline]
 mutex_lock_nested+0xa4/0xf8 kernel/locking/mutex.c:743
 rfcomm_dlc_exists+0xb0/0x32c net/bluetooth/rfcomm/core.c:542
 __rfcomm_create_dev net/bluetooth/rfcomm/tty.c:415 [inline]
 rfcomm_create_dev net/bluetooth/rfcomm/tty.c:486 [inline]
 rfcomm_dev_ioctl+0x938/0x2434 net/bluetooth/rfcomm/tty.c:588
 rfcomm_sock_ioctl+0x98/0xf0 net/bluetooth/rfcomm/sock.c:880
 sock_do_ioctl+0x134/0x2dc net/socket.c:1140
 sock_ioctl+0x4f0/0x8ac net/socket.c:1257
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:874 [inline]
 __se_sys_ioctl fs/ioctl.c:860 [inline]
 __arm64_sys_ioctl+0x14c/0x1c8 fs/ioctl.c:860
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:52
 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
 do_el0_svc+0x58/0x14c arch/arm64/kernel/syscall.c:181
 el0_svc+0x7c/0x1f0 arch/arm64/kernel/entry-common.c:608
 el0t_64_sync_handler+0x84/0xe4 arch/arm64/kernel/entry-common.c:626
 el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584