====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Tainted: G L ------------------------------------------------------ kworker/u34:0/67 is trying to acquire lock: ffffffff90f7e800 (rfcomm_mutex){+.+.}-{4:4}, at: rfcomm_security_cfm+0x3f/0x4b0 net/bluetooth/rfcomm/core.c:2222 but task is already holding lock: ffffffff90f51cc0 (hci_cb_list_lock){+.+.}-{4:4}, at: hci_auth_cfm include/net/bluetooth/hci_core.h:2199 [inline] ffffffff90f51cc0 (hci_cb_list_lock){+.+.}-{4:4}, at: hci_key_refresh_complete_evt+0x670/0x1030 net/bluetooth/hci_event.c:5263 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (hci_cb_list_lock){+.+.}-{4:4}: lock_acquire kernel/locking/lockdep.c:5908 [inline] lock_acquire+0x1d1/0x380 kernel/locking/lockdep.c:5865 __mutex_lock_common kernel/locking/mutex.c:646 [inline] __mutex_lock+0x1a4/0x1bd0 kernel/locking/mutex.c:821 hci_connect_cfm include/net/bluetooth/hci_core.h:2163 [inline] hci_remote_features_evt+0x485/0x9b0 net/bluetooth/hci_event.c:3786 hci_event_func net/bluetooth/hci_event.c:7887 [inline] hci_event_packet+0x8e9/0xcd0 net/bluetooth/hci_event.c:7938 hci_rx_work+0x451/0xfc0 net/bluetooth/hci_core.c:4041 process_one_work+0xac7/0x1b10 kernel/workqueue.c:3396 process_scheduled_works kernel/workqueue.c:3479 [inline] worker_thread+0x5ef/0xe50 kernel/workqueue.c:3560 kthread+0x373/0x450 kernel/kthread.c:436 ret_from_fork+0x730/0xd60 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 -> #1 (&hdev->lock){+.+.}-{4:4}: lock_acquire kernel/locking/lockdep.c:5908 [inline] lock_acquire+0x1d1/0x380 kernel/locking/lockdep.c:5865 __mutex_lock_common kernel/locking/mutex.c:646 [inline] __mutex_lock+0x1a4/0x1bd0 kernel/locking/mutex.c:821 l2cap_chan_connect+0xac/0x2050 net/bluetooth/l2cap_core.c:7266 l2cap_sock_connect+0x37a/0x770 net/bluetooth/l2cap_sock.c:255 kernel_connect+0x107/0x160 net/socket.c:3755 rfcomm_session_create net/bluetooth/rfcomm/core.c:808 [inline] __rfcomm_dlc_open net/bluetooth/rfcomm/core.c:385 [inline] rfcomm_dlc_open+0x838/0xac0 net/bluetooth/rfcomm/core.c:428 rfcomm_sock_connect+0x42c/0x690 net/bluetooth/rfcomm/sock.c:421 connect_socket net/socket.c:2141 [inline] connect_socket net/socket.c:2131 [inline] __sys_connect_file+0x146/0x1a0 net/socket.c:2166 __sys_connect+0x141/0x170 net/socket.c:2183 __do_sys_connect net/socket.c:2189 [inline] __se_sys_connect net/socket.c:2186 [inline] __x64_sys_connect+0x72/0xb0 net/socket.c:2186 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline] do_syscall_64+0x123/0x790 arch/x86/entry/syscall_64.c:84 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #0 (rfcomm_mutex){+.+.}-{4:4}: check_prev_add+0xeb/0xe60 kernel/locking/lockdep.c:3181 check_prevs_add kernel/locking/lockdep.c:3300 [inline] validate_chain kernel/locking/lockdep.c:3924 [inline] __lock_acquire+0x1492/0x1ec0 kernel/locking/lockdep.c:5254 lock_acquire kernel/locking/lockdep.c:5908 [inline] lock_acquire+0x1d1/0x380 kernel/locking/lockdep.c:5865 __mutex_lock_common kernel/locking/mutex.c:646 [inline] __mutex_lock+0x1a4/0x1bd0 kernel/locking/mutex.c:821 rfcomm_security_cfm+0x3f/0x4b0 net/bluetooth/rfcomm/core.c:2222 hci_auth_cfm include/net/bluetooth/hci_core.h:2202 [inline] hci_key_refresh_complete_evt+0x6ea/0x1030 net/bluetooth/hci_event.c:5263 hci_event_func net/bluetooth/hci_event.c:7887 [inline] hci_event_packet+0x8e9/0xcd0 net/bluetooth/hci_event.c:7938 hci_rx_work+0x451/0xfc0 net/bluetooth/hci_core.c:4041 process_one_work+0xac7/0x1b10 kernel/workqueue.c:3396 process_scheduled_works kernel/workqueue.c:3479 [inline] worker_thread+0x5ef/0xe50 kernel/workqueue.c:3560 kthread+0x373/0x450 kernel/kthread.c:436 ret_from_fork+0x730/0xd60 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 other info that might help us debug this: Chain exists of: rfcomm_mutex --> &hdev->lock --> hci_cb_list_lock Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(hci_cb_list_lock); lock(&hdev->lock); lock(hci_cb_list_lock); lock(rfcomm_mutex); *** DEADLOCK *** locks held by kworker/u34:0/67: 4, last CPU#3: #0: ffff8880583d1940 ((wq_completion)hci4#2){+.+.}-{0:0}, at: process_one_work+0x1466/0x1b10 kernel/workqueue.c:3371 #1: ffffc90000b4fd08 ((work_completion)(&hdev->rx_work)){+.+.}-{0:0}, at: process_one_work+0xa2c/0x1b10 kernel/workqueue.c:3372 #2: ffff88803a1500b8 (&hdev->lock){+.+.}-{4:4}, at: hci_key_refresh_complete_evt+0x3d/0x1030 net/bluetooth/hci_event.c:5233 #3: ffffffff90f51cc0 (hci_cb_list_lock){+.+.}-{4:4}, at: hci_auth_cfm include/net/bluetooth/hci_core.h:2199 [inline] #3: ffffffff90f51cc0 (hci_cb_list_lock){+.+.}-{4:4}, at: hci_key_refresh_complete_evt+0x670/0x1030 net/bluetooth/hci_event.c:5263 stack backtrace: CPU: 3 UID: 0 PID: 67 Comm: kworker/u34:0 Tainted: G L syzkaller #0 PREEMPT(full) Tainted: [L]=SOFTLOCKUP Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 Workqueue: hci4 hci_rx_work Call Trace: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120 print_circular_bug.cold+0x178/0x1be kernel/locking/lockdep.c:2059 check_noncircular+0x146/0x160 kernel/locking/lockdep.c:2191 check_prev_add+0xeb/0xe60 kernel/locking/lockdep.c:3181 check_prevs_add kernel/locking/lockdep.c:3300 [inline] validate_chain kernel/locking/lockdep.c:3924 [inline] __lock_acquire+0x1492/0x1ec0 kernel/locking/lockdep.c:5254 lock_acquire kernel/locking/lockdep.c:5908 [inline] lock_acquire+0x1d1/0x380 kernel/locking/lockdep.c:5865 __mutex_lock_common kernel/locking/mutex.c:646 [inline] __mutex_lock+0x1a4/0x1bd0 kernel/locking/mutex.c:821 rfcomm_security_cfm+0x3f/0x4b0 net/bluetooth/rfcomm/core.c:2222 hci_auth_cfm include/net/bluetooth/hci_core.h:2202 [inline] hci_key_refresh_complete_evt+0x6ea/0x1030 net/bluetooth/hci_event.c:5263 hci_event_func net/bluetooth/hci_event.c:7887 [inline] hci_event_packet+0x8e9/0xcd0 net/bluetooth/hci_event.c:7938 hci_rx_work+0x451/0xfc0 net/bluetooth/hci_core.c:4041 process_one_work+0xac7/0x1b10 kernel/workqueue.c:3396 process_scheduled_works kernel/workqueue.c:3479 [inline] worker_thread+0x5ef/0xe50 kernel/workqueue.c:3560 kthread+0x373/0x450 kernel/kthread.c:436 ret_from_fork+0x730/0xd60 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245