syzbot

======================================================
WARNING: possible circular locking dependency detected
6.4.0-rc3-syzkaller-00008-gae8373a5add4 #0 Not tainted
------------------------------------------------------
syz-executor231/5029 is trying to acquire lock:
ffff88802ab30130 (sk_lock-AF_BLUETOOTH-BTPROTO_RFCOMM){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1697 [inline]
ffff88802ab30130 (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:
ffff888021795928 (&d->lock){+.+.}-{3:3}, at: __rfcomm_dlc_close+0x15d/0x890 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+0x12f/0x1350 kernel/locking/mutex.c:747
       __rfcomm_dlc_close+0x15d/0x890 net/bluetooth/rfcomm/core.c:491
       rfcomm_dlc_close+0x1e9/0x240 net/bluetooth/rfcomm/core.c:524
       __rfcomm_sock_close+0x17a/0x2f0 net/bluetooth/rfcomm/sock.c:220
       rfcomm_sock_shutdown+0xd8/0x230 net/bluetooth/rfcomm/sock.c:912
       rfcomm_sock_release+0x68/0x140 net/bluetooth/rfcomm/sock.c:933
       __sock_release+0xcd/0x290 net/socket.c:653
       sock_close+0x1c/0x20 net/socket.c:1397
       __fput+0x27c/0xa90 fs/file_table.c:321
       task_work_run+0x16f/0x270 kernel/task_work.c:179
       exit_task_work include/linux/task_work.h:38 [inline]
       do_exit+0xad3/0x2960 kernel/exit.c:871
       do_group_exit+0xd4/0x2a0 kernel/exit.c:1021
       get_signal+0x2315/0x25b0 kernel/signal.c:2874
       arch_do_signal_or_restart+0x79/0x5c0 arch/x86/kernel/signal.c:306
       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:286 [inline]
       syscall_exit_to_user_mode+0x1d/0x50 kernel/entry/common.c:297
       do_syscall_64+0x46/0xb0 arch/x86/entry/common.c:86
       entry_SYSCALL_64_after_hwframe+0x63/0xcd

-> #2 (rfcomm_mutex){+.+.}-{3:3}:
       __mutex_lock_common kernel/locking/mutex.c:603 [inline]
       __mutex_lock+0x12f/0x1350 kernel/locking/mutex.c:747
       rfcomm_dlc_exists+0x58/0x190 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+0x966/0x1c00 net/bluetooth/rfcomm/tty.c:587
       rfcomm_sock_ioctl+0xb7/0xe0 net/bluetooth/rfcomm/sock.c:880
       sock_do_ioctl+0xcc/0x230 net/socket.c:1201
       sock_ioctl+0x1f8/0x680 net/socket.c:1318
       vfs_ioctl fs/ioctl.c:51 [inline]
       __do_sys_ioctl fs/ioctl.c:870 [inline]
       __se_sys_ioctl fs/ioctl.c:856 [inline]
       __x64_sys_ioctl+0x197/0x210 fs/ioctl.c:856
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x63/0xcd

-> #1 (rfcomm_ioctl_mutex){+.+.}-{3:3}:
       __mutex_lock_common kernel/locking/mutex.c:603 [inline]
       __mutex_lock+0x12f/0x1350 kernel/locking/mutex.c:747
       rfcomm_create_dev net/bluetooth/rfcomm/tty.c:484 [inline]
       rfcomm_dev_ioctl+0x8a2/0x1c00 net/bluetooth/rfcomm/tty.c:587
       rfcomm_sock_ioctl+0xb7/0xe0 net/bluetooth/rfcomm/sock.c:880
       sock_do_ioctl+0xcc/0x230 net/socket.c:1201
       sock_ioctl+0x1f8/0x680 net/socket.c:1318
       vfs_ioctl fs/ioctl.c:51 [inline]
       __do_sys_ioctl fs/ioctl.c:870 [inline]
       __se_sys_ioctl fs/ioctl.c:856 [inline]
       __x64_sys_ioctl+0x197/0x210 fs/ioctl.c:856
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x63/0xcd

-> #0 (sk_lock-AF_BLUETOOTH-BTPROTO_RFCOMM){+.+.}-{0:0}:
       check_prev_add kernel/locking/lockdep.c:3108 [inline]
       check_prevs_add kernel/locking/lockdep.c:3227 [inline]
       validate_chain kernel/locking/lockdep.c:3842 [inline]
       __lock_acquire+0x2f21/0x5df0 kernel/locking/lockdep.c:5074
       lock_acquire kernel/locking/lockdep.c:5691 [inline]
       lock_acquire+0x1b1/0x520 kernel/locking/lockdep.c:5656
       lock_sock_nested+0x3a/0xf0 net/core/sock.c:3469
       lock_sock include/net/sock.h:1697 [inline]
       rfcomm_sk_state_change+0x6d/0x3a0 net/bluetooth/rfcomm/sock.c:73
       __rfcomm_dlc_close+0x1b1/0x890 net/bluetooth/rfcomm/core.c:493
       rfcomm_dlc_close+0x1e9/0x240 net/bluetooth/rfcomm/core.c:524
       __rfcomm_sock_close+0x17a/0x2f0 net/bluetooth/rfcomm/sock.c:220
       rfcomm_sock_shutdown+0xd8/0x230 net/bluetooth/rfcomm/sock.c:912
       rfcomm_sock_release+0x68/0x140 net/bluetooth/rfcomm/sock.c:933
       __sock_release+0xcd/0x290 net/socket.c:653
       sock_close+0x1c/0x20 net/socket.c:1397
       __fput+0x27c/0xa90 fs/file_table.c:321
       task_work_run+0x16f/0x270 kernel/task_work.c:179
       exit_task_work include/linux/task_work.h:38 [inline]
       do_exit+0xad3/0x2960 kernel/exit.c:871
       do_group_exit+0xd4/0x2a0 kernel/exit.c:1021
       get_signal+0x2315/0x25b0 kernel/signal.c:2874
       arch_do_signal_or_restart+0x79/0x5c0 arch/x86/kernel/signal.c:306
       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:286 [inline]
       syscall_exit_to_user_mode+0x1d/0x50 kernel/entry/common.c:297
       do_syscall_64+0x46/0xb0 arch/x86/entry/common.c:86
       entry_SYSCALL_64_after_hwframe+0x63/0xcd

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-executor231/5029:
 #0: ffff88807694d010 (&sb->s_type->i_mutex_key#10){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:775 [inline]
 #0: ffff88807694d010 (&sb->s_type->i_mutex_key#10){+.+.}-{3:3}, at: __sock_release+0x86/0x290 net/socket.c:652
 #1: ffffffff8e371088 (rfcomm_mutex){+.+.}-{3:3}, at: rfcomm_dlc_close+0x33/0x240 net/bluetooth/rfcomm/core.c:511
 #2: ffff888021795928 (&d->lock){+.+.}-{3:3}, at: __rfcomm_dlc_close+0x15d/0x890 net/bluetooth/rfcomm/core.c:491

stack backtrace:
CPU: 0 PID: 5029 Comm: syz-executor231 Not tainted 6.4.0-rc3-syzkaller-00008-gae8373a5add4 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/28/2023
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xd9/0x150 lib/dump_stack.c:106
 check_noncircular+0x25f/0x2e0 kernel/locking/lockdep.c:2188
 check_prev_add kernel/locking/lockdep.c:3108 [inline]
 check_prevs_add kernel/locking/lockdep.c:3227 [inline]
 validate_chain kernel/locking/lockdep.c:3842 [inline]
 __lock_acquire+0x2f21/0x5df0 kernel/locking/lockdep.c:5074
 lock_acquire kernel/locking/lockdep.c:5691 [inline]
 lock_acquire+0x1b1/0x520 kernel/locking/lockdep.c:5656
 lock_sock_nested+0x3a/0xf0 net/core/sock.c:3469
 lock_sock include/net/sock.h:1697 [inline]
 rfcomm_sk_state_change+0x6d/0x3a0 net/bluetooth/rfcomm/sock.c:73
 __rfcomm_dlc_close+0x1b1/0x890 net/bluetooth/rfcomm/core.c:493
 rfcomm_dlc_close+0x1e9/0x240 net/bluetooth/rfcomm/core.c:524
 __rfcomm_sock_close+0x17a/0x2f0 net/bluetooth/rfcomm/sock.c:220
 rfcomm_sock_shutdown+0xd8/0x230 net/bluetooth/rfcomm/sock.c:912
 rfcomm_sock_release+0x68/0x140 net/bluetooth/rfcomm/sock.c:933
 __sock_release+0xcd/0x290 net/socket.c:653
 sock_close+0x1c/0x20 net/socket.c:1397
 __fput+0x27c/0xa90 fs/file_table.c:321
 task_work_run+0x16f/0x270 kernel/task_work.c:179
 exit_task_work include/linux/task_work.h:38 [inline]
 do_exit+0xad3/0x2960 kernel/exit.c:871
 do_group_exit+0xd4/0x2a0 kernel/exit.c:1021
 get_signal+0x2315/0x25b0 kernel/signal.c:2874
 arch_do_signal_or_restart+0x79/0x5c0 arch/x86/kernel/signal.c:306
 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:286 [inline]
 syscall_exit_to_user_mode+0x1d/0x50 kernel/entry/common.c:297
 do_syscall_64+0x46/0xb0 arch/x86/entry/common.c:86
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f7f016d7599
Code: Unable to access opcode bytes at 0x7f7f016d756f.
RSP: 002b:00007ffe2870a098 EFLAGS: 00000246 ORIG_RAX: 000000000000002a
RAX: fffffffffffffffc RBX: 00000000000f4240 RCX: 00007f7f016d7599
RDX: 000000000000000a RSI: 0000000020000180 RDI: 0000000000000003
RBP: 0000000000000000 R08: 0000000000000150 R09: 0000000000000150
R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffe2870a140
R13: 00007ffe2870a110 R14: 00007ffe2870a100 R15: 0000000000000003
 </TASK>