====================================================== WARNING: possible circular locking dependency detected 6.1.112-syzkaller #0 Not tainted ------------------------------------------------------ syz.2.556/6225 is trying to acquire lock: ffff800018165308 (rfcomm_mutex){+.+.}-{3:3}, at: rfcomm_dlc_exists+0xb0/0x32c net/bluetooth/rfcomm/core.c:542 but task is already holding lock: ffff800018168c88 (rfcomm_ioctl_mutex){+.+.}-{3:3}, at: rfcomm_create_dev net/bluetooth/rfcomm/tty.c:484 [inline] ffff800018168c88 (rfcomm_ioctl_mutex){+.+.}-{3:3}, at: rfcomm_dev_ioctl+0x258/0x22a8 net/bluetooth/rfcomm/tty.c:587 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+0x190/0x21a0 kernel/locking/mutex.c:603 __mutex_lock kernel/locking/mutex.c:747 [inline] mutex_lock_nested+0x38/0x44 kernel/locking/mutex.c:799 rfcomm_create_dev net/bluetooth/rfcomm/tty.c:484 [inline] rfcomm_dev_ioctl+0x258/0x22a8 net/bluetooth/rfcomm/tty.c:587 rfcomm_sock_ioctl+0x98/0xf0 net/bluetooth/rfcomm/sock.c:869 sock_do_ioctl+0x134/0x2dc net/socket.c:1204 sock_ioctl+0x4ec/0x858 net/socket.c:1321 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:870 [inline] __se_sys_ioctl fs/ioctl.c:856 [inline] __arm64_sys_ioctl+0x14c/0x1c8 fs/ioctl.c:856 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x2c0 arch/arm64/kernel/syscall.c:52 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:140 do_el0_svc+0x64/0x218 arch/arm64/kernel/syscall.c:204 el0_svc+0x58/0x168 arch/arm64/kernel/entry-common.c:637 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585 -> #2 (sk_lock-AF_BLUETOOTH-BTPROTO_RFCOMM){+.+.}-{0:0}: lock_sock_nested+0x78/0x138 net/core/sock.c:3485 lock_sock include/net/sock.h:1748 [inline] rfcomm_sk_state_change+0x60/0x2c8 net/bluetooth/rfcomm/sock.c:73 __rfcomm_dlc_close+0x234/0x600 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:901 rfcomm_sock_release+0x58/0x114 net/bluetooth/rfcomm/sock.c:922 __sock_release net/socket.c:654 [inline] sock_close+0xb8/0x1fc net/socket.c:1400 __fput+0x1c8/0x7c8 fs/file_table.c:320 ____fput+0x20/0x30 fs/file_table.c:348 task_work_run+0x240/0x2f0 kernel/task_work.c:203 get_signal+0x1394/0x158c kernel/signal.c:2647 do_signal arch/arm64/kernel/signal.c:1076 [inline] do_notify_resume+0x3ac/0x3474 arch/arm64/kernel/signal.c:1129 prepare_exit_to_user_mode arch/arm64/kernel/entry-common.c:137 [inline] exit_to_user_mode arch/arm64/kernel/entry-common.c:142 [inline] el0_svc+0x9c/0x168 arch/arm64/kernel/entry-common.c:638 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585 -> #1 (&d->lock){+.+.}-{3:3}: __mutex_lock_common+0x190/0x21a0 kernel/locking/mutex.c:603 __mutex_lock kernel/locking/mutex.c:747 [inline] mutex_lock_nested+0x38/0x44 kernel/locking/mutex.c:799 __rfcomm_dlc_close+0x1f8/0x600 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:901 rfcomm_sock_release+0x58/0x114 net/bluetooth/rfcomm/sock.c:922 __sock_release net/socket.c:654 [inline] sock_close+0xb8/0x1fc net/socket.c:1400 __fput+0x1c8/0x7c8 fs/file_table.c:320 ____fput+0x20/0x30 fs/file_table.c:348 task_work_run+0x240/0x2f0 kernel/task_work.c:203 get_signal+0x1394/0x158c kernel/signal.c:2647 do_signal arch/arm64/kernel/signal.c:1076 [inline] do_notify_resume+0x3ac/0x3474 arch/arm64/kernel/signal.c:1129 prepare_exit_to_user_mode arch/arm64/kernel/entry-common.c:137 [inline] exit_to_user_mode arch/arm64/kernel/entry-common.c:142 [inline] el0_svc+0x9c/0x168 arch/arm64/kernel/entry-common.c:638 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585 -> #0 (rfcomm_mutex){+.+.}-{3:3}: check_prev_add kernel/locking/lockdep.c:3090 [inline] check_prevs_add kernel/locking/lockdep.c:3209 [inline] validate_chain kernel/locking/lockdep.c:3825 [inline] __lock_acquire+0x3338/0x7680 kernel/locking/lockdep.c:5049 lock_acquire+0x26c/0x7cc kernel/locking/lockdep.c:5662 __mutex_lock_common+0x190/0x21a0 kernel/locking/mutex.c:603 __mutex_lock kernel/locking/mutex.c:747 [inline] mutex_lock_nested+0x38/0x44 kernel/locking/mutex.c:799 rfcomm_dlc_exists+0xb0/0x32c 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+0x888/0x22a8 net/bluetooth/rfcomm/tty.c:587 rfcomm_sock_ioctl+0x98/0xf0 net/bluetooth/rfcomm/sock.c:869 sock_do_ioctl+0x134/0x2dc net/socket.c:1204 sock_ioctl+0x4ec/0x858 net/socket.c:1321 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:870 [inline] __se_sys_ioctl fs/ioctl.c:856 [inline] __arm64_sys_ioctl+0x14c/0x1c8 fs/ioctl.c:856 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x2c0 arch/arm64/kernel/syscall.c:52 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:140 do_el0_svc+0x64/0x218 arch/arm64/kernel/syscall.c:204 el0_svc+0x58/0x168 arch/arm64/kernel/entry-common.c:637 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585 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.2.556/6225: #0: ffff0000ef88a130 (sk_lock-AF_BLUETOOTH-BTPROTO_RFCOMM){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1748 [inline] #0: ffff0000ef88a130 (sk_lock-AF_BLUETOOTH-BTPROTO_RFCOMM){+.+.}-{0:0}, at: rfcomm_sock_ioctl+0x88/0xf0 net/bluetooth/rfcomm/sock.c:868 #1: ffff800018168c88 (rfcomm_ioctl_mutex){+.+.}-{3:3}, at: rfcomm_create_dev net/bluetooth/rfcomm/tty.c:484 [inline] #1: ffff800018168c88 (rfcomm_ioctl_mutex){+.+.}-{3:3}, at: rfcomm_dev_ioctl+0x258/0x22a8 net/bluetooth/rfcomm/tty.c:587 stack backtrace: CPU: 0 PID: 6225 Comm: syz.2.556 Not tainted 6.1.112-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/06/2024 Call trace: dump_backtrace+0x1c8/0x1f4 arch/arm64/kernel/stacktrace.c:158 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:165 __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:2048 check_noncircular+0x2cc/0x378 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 kernel/locking/lockdep.c:3825 [inline] __lock_acquire+0x3338/0x7680 kernel/locking/lockdep.c:5049 lock_acquire+0x26c/0x7cc kernel/locking/lockdep.c:5662 __mutex_lock_common+0x190/0x21a0 kernel/locking/mutex.c:603 __mutex_lock kernel/locking/mutex.c:747 [inline] mutex_lock_nested+0x38/0x44 kernel/locking/mutex.c:799 rfcomm_dlc_exists+0xb0/0x32c 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+0x888/0x22a8 net/bluetooth/rfcomm/tty.c:587 rfcomm_sock_ioctl+0x98/0xf0 net/bluetooth/rfcomm/sock.c:869 sock_do_ioctl+0x134/0x2dc net/socket.c:1204 sock_ioctl+0x4ec/0x858 net/socket.c:1321 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:870 [inline] __se_sys_ioctl fs/ioctl.c:856 [inline] __arm64_sys_ioctl+0x14c/0x1c8 fs/ioctl.c:856 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x2c0 arch/arm64/kernel/syscall.c:52 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:140 do_el0_svc+0x64/0x218 arch/arm64/kernel/syscall.c:204 el0_svc+0x58/0x168 arch/arm64/kernel/entry-common.c:637 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585