======================================================
WARNING: possible circular locking dependency detected
6.8.0-rc7-syzkaller-g707081b61156 #0 Not tainted
------------------------------------------------------
syz-executor170/6191 is trying to acquire lock:
ffff0000d54af130 (sk_lock-AF_BLUETOOTH-BTPROTO_RFCOMM){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1691 [inline]
ffff0000d54af130 (sk_lock-AF_BLUETOOTH-BTPROTO_RFCOMM){+.+.}-{0:0}, at: rfcomm_sk_state_change+0x60/0x2c8 net/bluetooth/rfcomm/sock.c:73

but task is already holding lock:
ffff0000d4a0bd28 (&d->lock){+.+.}-{3:3}, at: __rfcomm_dlc_close+0x1f8/0x608 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+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:905
       rfcomm_sock_release+0x58/0x114 net/bluetooth/rfcomm/sock.c:926
       __sock_release net/socket.c:659 [inline]
       sock_close+0xa4/0x1e8 net/socket.c:1421
       __fput+0x30c/0x738 fs/file_table.c:376
       ____fput+0x20/0x30 fs/file_table.c:404
       task_work_run+0x230/0x2e0 kernel/task_work.c:180
       exit_task_work include/linux/task_work.h:38 [inline]
       do_exit+0x618/0x1f64 kernel/exit.c:871
       do_group_exit+0x194/0x22c kernel/exit.c:1020
       get_signal+0x1500/0x15ec kernel/signal.c:2893
       do_signal+0x238/0x3e8c arch/arm64/kernel/signal.c:1308
       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:713
       el0t_64_sync_handler+0x84/0xfc arch/arm64/kernel/entry-common.c:730
       el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:598

-> #2 (rfcomm_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_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+0x888/0x22ac net/bluetooth/rfcomm/tty.c:587
       rfcomm_sock_ioctl+0x98/0xf0 net/bluetooth/rfcomm/sock.c:873
       sock_do_ioctl+0x134/0x2d0 net/socket.c:1222
       sock_ioctl+0x4ec/0x838 net/socket.c:1341
       vfs_ioctl fs/ioctl.c:51 [inline]
       __do_sys_ioctl fs/ioctl.c:871 [inline]
       __se_sys_ioctl fs/ioctl.c:857 [inline]
       __arm64_sys_ioctl+0x14c/0x1c8 fs/ioctl.c:857
       __invoke_syscall arch/arm64/kernel/syscall.c:34 [inline]
       invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:48
       el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:133
       do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:152
       el0_svc+0x54/0x168 arch/arm64/kernel/entry-common.c:712
       el0t_64_sync_handler+0x84/0xfc arch/arm64/kernel/entry-common.c:730
       el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:598

-> #1 (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+0x258/0x22ac net/bluetooth/rfcomm/tty.c:587
       rfcomm_sock_ioctl+0x98/0xf0 net/bluetooth/rfcomm/sock.c:873
       sock_do_ioctl+0x134/0x2d0 net/socket.c:1222
       sock_ioctl+0x4ec/0x838 net/socket.c:1341
       vfs_ioctl fs/ioctl.c:51 [inline]
       __do_sys_ioctl fs/ioctl.c:871 [inline]
       __se_sys_ioctl fs/ioctl.c:857 [inline]
       __arm64_sys_ioctl+0x14c/0x1c8 fs/ioctl.c:857
       __invoke_syscall arch/arm64/kernel/syscall.c:34 [inline]
       invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:48
       el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:133
       do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:152
       el0_svc+0x54/0x168 arch/arm64/kernel/entry-common.c:712
       el0t_64_sync_handler+0x84/0xfc arch/arm64/kernel/entry-common.c:730
       el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:598

-> #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+0x3384/0x763c kernel/locking/lockdep.c:5137
       lock_acquire+0x23c/0x71c kernel/locking/lockdep.c:5754
       lock_sock_nested+0x5c/0x11c net/core/sock.c:3523
       lock_sock include/net/sock.h:1691 [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:905
       rfcomm_sock_release+0x58/0x114 net/bluetooth/rfcomm/sock.c:926
       __sock_release net/socket.c:659 [inline]
       sock_close+0xa4/0x1e8 net/socket.c:1421
       __fput+0x30c/0x738 fs/file_table.c:376
       ____fput+0x20/0x30 fs/file_table.c:404
       task_work_run+0x230/0x2e0 kernel/task_work.c:180
       exit_task_work include/linux/task_work.h:38 [inline]
       do_exit+0x618/0x1f64 kernel/exit.c:871
       do_group_exit+0x194/0x22c kernel/exit.c:1020
       get_signal+0x1500/0x15ec kernel/signal.c:2893
       do_signal+0x238/0x3e8c arch/arm64/kernel/signal.c:1308
       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:713
       el0t_64_sync_handler+0x84/0xfc arch/arm64/kernel/entry-common.c:730
       el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:598

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-executor170/6191:
 #0: ffff0000de908810 (&sb->s_type->i_mutex_key#10){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:804 [inline]
 #0: ffff0000de908810 (&sb->s_type->i_mutex_key#10){+.+.}-{3:3}, at: __sock_release net/socket.c:658 [inline]
 #0: ffff0000de908810 (&sb->s_type->i_mutex_key#10){+.+.}-{3:3}, at: sock_close+0x80/0x1e8 net/socket.c:1421
 #1: ffff800091acf1a8 (rfcomm_mutex){+.+.}-{3:3}, at: rfcomm_dlc_close+0x44/0x194 net/bluetooth/rfcomm/core.c:511
 #2: ffff0000d4a0bd28 (&d->lock){+.+.}-{3:3}, at: __rfcomm_dlc_close+0x1f8/0x608 net/bluetooth/rfcomm/core.c:491

stack backtrace:
CPU: 0 PID: 6191 Comm: syz-executor170 Not tainted 6.8.0-rc7-syzkaller-g707081b61156 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/29/2024
Call trace:
 dump_backtrace+0x1b8/0x1e4 arch/arm64/kernel/stacktrace.c:291
 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:298
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xd0/0x124 lib/dump_stack.c:106
 dump_stack+0x1c/0x28 lib/dump_stack.c:113
 print_circular_bug+0x150/0x1b8 kernel/locking/lockdep.c:2060
 check_noncircular+0x310/0x404 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+0x3384/0x763c kernel/locking/lockdep.c:5137
 lock_acquire+0x23c/0x71c kernel/locking/lockdep.c:5754
 lock_sock_nested+0x5c/0x11c net/core/sock.c:3523
 lock_sock include/net/sock.h:1691 [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:905
 rfcomm_sock_release+0x58/0x114 net/bluetooth/rfcomm/sock.c:926
 __sock_release net/socket.c:659 [inline]
 sock_close+0xa4/0x1e8 net/socket.c:1421
 __fput+0x30c/0x738 fs/file_table.c:376
 ____fput+0x20/0x30 fs/file_table.c:404
 task_work_run+0x230/0x2e0 kernel/task_work.c:180
 exit_task_work include/linux/task_work.h:38 [inline]
 do_exit+0x618/0x1f64 kernel/exit.c:871
 do_group_exit+0x194/0x22c kernel/exit.c:1020
 get_signal+0x1500/0x15ec kernel/signal.c:2893
 do_signal+0x238/0x3e8c arch/arm64/kernel/signal.c:1308
 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:713
 el0t_64_sync_handler+0x84/0xfc arch/arm64/kernel/entry-common.c:730
 el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:598