syzbot

======================================================
WARNING: possible circular locking dependency detected
6.7.0-rc4-syzkaller-00009-gbee0e7762ad2 #0 Not tainted
------------------------------------------------------
syz-executor178/5100 is trying to acquire lock:
ffff888073cfc130 (sk_lock-AF_BLUETOOTH-BTPROTO_RFCOMM){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1720 [inline]
ffff888073cfc130 (sk_lock-AF_BLUETOOTH-BTPROTO_RFCOMM){+.+.}-{0:0}, at: rfcomm_sk_state_change+0x6d/0x3a0 net/bluetooth/rfcomm/sock.c:73

but task is already holding lock:
ffff8880297ad128 (&d->lock){+.+.}-{3:3}, at: __rfcomm_dlc_close+0x231/0x720 net/bluetooth/rfcomm/core.c:491

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #3 (&d->lock){+.+.}-{3:3}:
       __mutex_lock_common kernel/locking/mutex.c:603 [inline]
       __mutex_lock+0x175/0x9d0 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+0x270/0xbb0 fs/file_table.c:394
       task_work_run+0x14d/0x240 kernel/task_work.c:180
       exit_task_work include/linux/task_work.h:38 [inline]
       do_exit+0xa92/0x2ae0 kernel/exit.c:871
       do_group_exit+0xd4/0x2a0 kernel/exit.c:1021
       get_signal+0x23be/0x2790 kernel/signal.c:2904
       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+0x121/0x240 kernel/entry/common.c:204
       __syscall_exit_to_user_mode_work kernel/entry/common.c:285 [inline]
       syscall_exit_to_user_mode+0x1e/0x60 kernel/entry/common.c:296
       do_syscall_64+0x4d/0x110 arch/x86/entry/common.c:88
       entry_SYSCALL_64_after_hwframe+0x63/0x6b

-> #2 (rfcomm_mutex){+.+.}-{3:3}:
       __mutex_lock_common kernel/locking/mutex.c:603 [inline]
       __mutex_lock+0x175/0x9d0 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+0x22e/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:51 [inline]
       do_syscall_64+0x40/0x110 arch/x86/entry/common.c:82
       entry_SYSCALL_64_after_hwframe+0x63/0x6b

-> #1 (rfcomm_ioctl_mutex){+.+.}-{3:3}:
       __mutex_lock_common kernel/locking/mutex.c:603 [inline]
       __mutex_lock+0x175/0x9d0 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+0x22e/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:51 [inline]
       do_syscall_64+0x40/0x110 arch/x86/entry/common.c:82
       entry_SYSCALL_64_after_hwframe+0x63/0x6b

-> #0 (sk_lock-AF_BLUETOOTH-BTPROTO_RFCOMM){+.+.}-{0:0}:
       check_prev_add kernel/locking/lockdep.c:3134 [inline]
       check_prevs_add kernel/locking/lockdep.c:3253 [inline]
       validate_chain kernel/locking/lockdep.c:3869 [inline]
       __lock_acquire+0x2433/0x3b20 kernel/locking/lockdep.c:5137
       lock_acquire kernel/locking/lockdep.c:5754 [inline]
       lock_acquire+0x1ae/0x520 kernel/locking/lockdep.c:5719
       lock_sock_nested+0x3a/0xf0 net/core/sock.c:3519
       lock_sock include/net/sock.h:1720 [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+0x270/0xbb0 fs/file_table.c:394
       task_work_run+0x14d/0x240 kernel/task_work.c:180
       exit_task_work include/linux/task_work.h:38 [inline]
       do_exit+0xa92/0x2ae0 kernel/exit.c:871
       do_group_exit+0xd4/0x2a0 kernel/exit.c:1021
       get_signal+0x23be/0x2790 kernel/signal.c:2904
       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+0x121/0x240 kernel/entry/common.c:204
       __syscall_exit_to_user_mode_work kernel/entry/common.c:285 [inline]
       syscall_exit_to_user_mode+0x1e/0x60 kernel/entry/common.c:296
       do_syscall_64+0x4d/0x110 arch/x86/entry/common.c:88
       entry_SYSCALL_64_after_hwframe+0x63/0x6b

other info that might help us debug this:

Chain exists of:
  sk_lock-AF_BLUETOOTH-BTPROTO_RFCOMM --> rfcomm_mutex --> &d->lock

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&d->lock);
                               lock(rfcomm_mutex);
                               lock(&d->lock);
  lock(sk_lock-AF_BLUETOOTH-BTPROTO_RFCOMM);

 *** DEADLOCK ***

3 locks held by syz-executor178/5100:
 #0: ffff88807497d610 (&sb->s_type->i_mutex_key#10){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:802 [inline]
 #0: ffff88807497d610 (&sb->s_type->i_mutex_key#10){+.+.}-{3:3}, at: __sock_release+0x86/0x260 net/socket.c:658
 #1: ffffffff8ed3ac88 (rfcomm_mutex){+.+.}-{3:3}, at: rfcomm_dlc_close+0x33/0x240 net/bluetooth/rfcomm/core.c:511
 #2: ffff8880297ad128 (&d->lock){+.+.}-{3:3}, at: __rfcomm_dlc_close+0x231/0x720 net/bluetooth/rfcomm/core.c:491

stack backtrace:
CPU: 1 PID: 5100 Comm: syz-executor178 Not tainted 6.7.0-rc4-syzkaller-00009-gbee0e7762ad2 #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+0xd9/0x1b0 lib/dump_stack.c:106
 check_noncircular+0x317/0x400 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:3869 [inline]
 __lock_acquire+0x2433/0x3b20 kernel/locking/lockdep.c:5137
 lock_acquire kernel/locking/lockdep.c:5754 [inline]
 lock_acquire+0x1ae/0x520 kernel/locking/lockdep.c:5719
 lock_sock_nested+0x3a/0xf0 net/core/sock.c:3519
 lock_sock include/net/sock.h:1720 [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+0x270/0xbb0 fs/file_table.c:394
 task_work_run+0x14d/0x240 kernel/task_work.c:180
 exit_task_work include/linux/task_work.h:38 [inline]
 do_exit+0xa92/0x2ae0 kernel/exit.c:871
 do_group_exit+0xd4/0x2a0 kernel/exit.c:1021
 get_signal+0x23be/0x2790 kernel/signal.c:2904
 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+0x121/0x240 kernel/entry/common.c:204
 __syscall_exit_to_user_mode_work kernel/entry/common.c:285 [inline]
 syscall_exit_to_user_mode+0x1e/0x60 kernel/entry/common.c:296
 do_syscall_64+0x4d/0x110 arch/x86/entry/common.c:88
 entry_SYSCALL_64_after_hwframe+0x63/0x6b
RIP: 0033:0x7fa7c0511f79
Code: Unable to access opcode bytes at 0x7fa7c0511f4f.
RSP: 002b:00007ffe678679e8 EFLAGS: 00000246 ORIG_RAX: 000000000000002a
RAX: fffffffffffffffc RBX: 0000000000000000 RCX: 00007fa7c0511f79
RDX: 000000000000000a RSI: 0000000020000200 RDI: 0000000000000004
RBP: 00000000000f4240 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000555556115370
R13: 0000000000000002 R14: 00007ffe67867a60 R15: 00007ffe67867a50
 </TASK>