syzbot

======================================================
WARNING: possible circular locking dependency detected
6.1.87-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor423/3572 is trying to acquire lock:
ffff888017ae4130 (sk_lock-AF_BLUETOOTH-BTPROTO_RFCOMM){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1745 [inline]
ffff888017ae4130 (sk_lock-AF_BLUETOOTH-BTPROTO_RFCOMM){+.+.}-{0:0}, at: rfcomm_sk_state_change+0x57/0x300 net/bluetooth/rfcomm/sock.c:73

but task is already holding lock:
ffff8880285e8d28 (&d->lock){+.+.}-{3:3}, at: __rfcomm_dlc_close+0x259/0x6d0 net/bluetooth/rfcomm/core.c:487

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #3 (&d->lock){+.+.}-{3:3}:
       lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5662
       __mutex_lock_common kernel/locking/mutex.c:603 [inline]
       __mutex_lock+0x132/0xd80 kernel/locking/mutex.c:747
       __rfcomm_dlc_close+0x259/0x6d0 net/bluetooth/rfcomm/core.c:487
       rfcomm_dlc_close+0xed/0x180 net/bluetooth/rfcomm/core.c:520
       __rfcomm_sock_close+0x104/0x220 net/bluetooth/rfcomm/sock.c:220
       rfcomm_sock_shutdown+0xb4/0x230 net/bluetooth/rfcomm/sock.c:912
       rfcomm_sock_release+0x55/0x110 net/bluetooth/rfcomm/sock.c:933
       __sock_release net/socket.c:654 [inline]
       sock_close+0xcd/0x230 net/socket.c:1400
       __fput+0x3b7/0x890 fs/file_table.c:320
       task_work_run+0x246/0x300 kernel/task_work.c:179
       exit_task_work include/linux/task_work.h:38 [inline]
       do_exit+0xa73/0x26a0 kernel/exit.c:869
       do_group_exit+0x202/0x2b0 kernel/exit.c:1019
       get_signal+0x16f7/0x17d0 kernel/signal.c:2862
       arch_do_signal_or_restart+0xb0/0x1a10 arch/x86/kernel/signal.c:871
       exit_to_user_mode_loop+0x6a/0x100 kernel/entry/common.c:174
       exit_to_user_mode_prepare+0xb1/0x140 kernel/entry/common.c:210
       __syscall_exit_to_user_mode_work kernel/entry/common.c:292 [inline]
       syscall_exit_to_user_mode+0x60/0x270 kernel/entry/common.c:303
       do_syscall_64+0x47/0xb0 arch/x86/entry/common.c:87
       entry_SYSCALL_64_after_hwframe+0x68/0xd2

-> #2 (rfcomm_mutex){+.+.}-{3:3}:
       lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5662
       __mutex_lock_common kernel/locking/mutex.c:603 [inline]
       __mutex_lock+0x132/0xd80 kernel/locking/mutex.c:747
       rfcomm_dlc_exists+0xa2/0x370 net/bluetooth/rfcomm/core.c:542
       __rfcomm_create_dev net/bluetooth/rfcomm/tty.c:414 [inline]
       rfcomm_create_dev net/bluetooth/rfcomm/tty.c:485 [inline]
       rfcomm_dev_ioctl+0xb2d/0x2180 net/bluetooth/rfcomm/tty.c:587
       rfcomm_sock_ioctl+0x82/0xc0 net/bluetooth/rfcomm/sock.c:880
       sock_do_ioctl+0x152/0x450 net/socket.c:1204
       sock_ioctl+0x47f/0x770 net/socket.c:1321
       vfs_ioctl fs/ioctl.c:51 [inline]
       __do_sys_ioctl fs/ioctl.c:870 [inline]
       __se_sys_ioctl+0xf1/0x160 fs/ioctl.c:856
       do_syscall_x64 arch/x86/entry/common.c:51 [inline]
       do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:81
       entry_SYSCALL_64_after_hwframe+0x68/0xd2

-> #1 (rfcomm_ioctl_mutex){+.+.}-{3:3}:
       lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5662
       __mutex_lock_common kernel/locking/mutex.c:603 [inline]
       __mutex_lock+0x132/0xd80 kernel/locking/mutex.c:747
       rfcomm_create_dev net/bluetooth/rfcomm/tty.c:484 [inline]
       rfcomm_dev_ioctl+0x233/0x2180 net/bluetooth/rfcomm/tty.c:587
       rfcomm_sock_ioctl+0x82/0xc0 net/bluetooth/rfcomm/sock.c:880
       sock_do_ioctl+0x152/0x450 net/socket.c:1204
       sock_ioctl+0x47f/0x770 net/socket.c:1321
       vfs_ioctl fs/ioctl.c:51 [inline]
       __do_sys_ioctl fs/ioctl.c:870 [inline]
       __se_sys_ioctl+0xf1/0x160 fs/ioctl.c:856
       do_syscall_x64 arch/x86/entry/common.c:51 [inline]
       do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:81
       entry_SYSCALL_64_after_hwframe+0x68/0xd2

-> #0 (sk_lock-AF_BLUETOOTH-BTPROTO_RFCOMM){+.+.}-{0:0}:
       check_prev_add kernel/locking/lockdep.c:3090 [inline]
       check_prevs_add kernel/locking/lockdep.c:3209 [inline]
       validate_chain+0x1661/0x5950 kernel/locking/lockdep.c:3825
       __lock_acquire+0x125b/0x1f80 kernel/locking/lockdep.c:5049
       lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5662
       lock_sock_nested+0x44/0x100 net/core/sock.c:3484
       lock_sock include/net/sock.h:1745 [inline]
       rfcomm_sk_state_change+0x57/0x300 net/bluetooth/rfcomm/sock.c:73
       __rfcomm_dlc_close+0x2b2/0x6d0 net/bluetooth/rfcomm/core.c:489
       rfcomm_dlc_close+0xed/0x180 net/bluetooth/rfcomm/core.c:520
       __rfcomm_sock_close+0x104/0x220 net/bluetooth/rfcomm/sock.c:220
       rfcomm_sock_shutdown+0xb4/0x230 net/bluetooth/rfcomm/sock.c:912
       rfcomm_sock_release+0x55/0x110 net/bluetooth/rfcomm/sock.c:933
       __sock_release net/socket.c:654 [inline]
       sock_close+0xcd/0x230 net/socket.c:1400
       __fput+0x3b7/0x890 fs/file_table.c:320
       task_work_run+0x246/0x300 kernel/task_work.c:179
       exit_task_work include/linux/task_work.h:38 [inline]
       do_exit+0xa73/0x26a0 kernel/exit.c:869
       do_group_exit+0x202/0x2b0 kernel/exit.c:1019
       get_signal+0x16f7/0x17d0 kernel/signal.c:2862
       arch_do_signal_or_restart+0xb0/0x1a10 arch/x86/kernel/signal.c:871
       exit_to_user_mode_loop+0x6a/0x100 kernel/entry/common.c:174
       exit_to_user_mode_prepare+0xb1/0x140 kernel/entry/common.c:210
       __syscall_exit_to_user_mode_work kernel/entry/common.c:292 [inline]
       syscall_exit_to_user_mode+0x60/0x270 kernel/entry/common.c:303
       do_syscall_64+0x47/0xb0 arch/x86/entry/common.c:87
       entry_SYSCALL_64_after_hwframe+0x68/0xd2

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-executor423/3572:
 #0: ffff88806f403e10 (&sb->s_type->i_mutex_key#10){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:758 [inline]
 #0: ffff88806f403e10 (&sb->s_type->i_mutex_key#10){+.+.}-{3:3}, at: __sock_release net/socket.c:653 [inline]
 #0: ffff88806f403e10 (&sb->s_type->i_mutex_key#10){+.+.}-{3:3}, at: sock_close+0x98/0x230 net/socket.c:1400
 #1: ffffffff8e414e88 (rfcomm_mutex){+.+.}-{3:3}, at: rfcomm_dlc_close+0x37/0x180 net/bluetooth/rfcomm/core.c:507
 #2: ffff8880285e8d28 (&d->lock){+.+.}-{3:3}, at: __rfcomm_dlc_close+0x259/0x6d0 net/bluetooth/rfcomm/core.c:487

stack backtrace:
CPU: 1 PID: 3572 Comm: syz-executor423 Not tainted 6.1.87-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+0x1e3/0x2cb lib/dump_stack.c:106
 check_noncircular+0x2fa/0x3b0 kernel/locking/lockdep.c:2170
 check_prev_add kernel/locking/lockdep.c:3090 [inline]
 check_prevs_add kernel/locking/lockdep.c:3209 [inline]
 validate_chain+0x1661/0x5950 kernel/locking/lockdep.c:3825
 __lock_acquire+0x125b/0x1f80 kernel/locking/lockdep.c:5049
 lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5662
 lock_sock_nested+0x44/0x100 net/core/sock.c:3484
 lock_sock include/net/sock.h:1745 [inline]
 rfcomm_sk_state_change+0x57/0x300 net/bluetooth/rfcomm/sock.c:73
 __rfcomm_dlc_close+0x2b2/0x6d0 net/bluetooth/rfcomm/core.c:489
 rfcomm_dlc_close+0xed/0x180 net/bluetooth/rfcomm/core.c:520
 __rfcomm_sock_close+0x104/0x220 net/bluetooth/rfcomm/sock.c:220
 rfcomm_sock_shutdown+0xb4/0x230 net/bluetooth/rfcomm/sock.c:912
 rfcomm_sock_release+0x55/0x110 net/bluetooth/rfcomm/sock.c:933
 __sock_release net/socket.c:654 [inline]
 sock_close+0xcd/0x230 net/socket.c:1400
 __fput+0x3b7/0x890 fs/file_table.c:320
 task_work_run+0x246/0x300 kernel/task_work.c:179
 exit_task_work include/linux/task_work.h:38 [inline]
 do_exit+0xa73/0x26a0 kernel/exit.c:869
 do_group_exit+0x202/0x2b0 kernel/exit.c:1019
 get_signal+0x16f7/0x17d0 kernel/signal.c:2862
 arch_do_signal_or_restart+0xb0/0x1a10 arch/x86/kernel/signal.c:871
 exit_to_user_mode_loop+0x6a/0x100 kernel/entry/common.c:174
 exit_to_user_mode_prepare+0xb1/0x140 kernel/entry/common.c:210
 __syscall_exit_to_user_mode_work kernel/entry/common.c:292 [inline]
 syscall_exit_to_user_mode+0x60/0x270 kernel/entry/common.c:303
 do_syscall_64+0x47/0xb0 arch/x86/entry/common.c:87
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7ff8ba758fb9
Code: Unable to access opcode bytes at 0x7ff8ba758f8f.
RSP: 002b:00007fff901e1808 EFLAGS: 00000246 ORIG_RAX: 000000000000002a
RAX: fffffffffffffffc RBX: 0000000000000000 RCX: 00007ff8ba758fb9
RDX: 000000000000000a RSI: 0000000020000200 RDI: 0000000000000004
RBP: 00000000000f4240 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000004 R14: 00007fff901e1880 R15: 00007fff901e1870
 </TASK>