====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Not tainted ------------------------------------------------------ syz.4.5320/27280 is trying to acquire lock: ffff8880321e00b8 (&hdev->lock){+.+.}-{3:3}, at: l2cap_chan_connect+0xfc/0xe30 net/bluetooth/l2cap_core.c:7195 but task is already holding lock: ffffffff8f364ac8 (rfcomm_mutex){+.+.}-{3:3}, at: rfcomm_dlc_open+0x95/0xec0 net/bluetooth/rfcomm/core.c:429 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (rfcomm_mutex){+.+.}-{3:3}: __mutex_lock_common kernel/locking/mutex.c:603 [inline] __mutex_lock+0x135/0xc80 kernel/locking/mutex.c:747 rfcomm_security_cfm+0x41/0x550 net/bluetooth/rfcomm/core.c:2220 hci_auth_cfm include/net/bluetooth/hci_core.h:2040 [inline] hci_auth_complete_evt+0x366/0xba0 net/bluetooth/hci_event.c:3470 hci_event_func net/bluetooth/hci_event.c:7500 [inline] hci_event_packet+0x807/0x1280 net/bluetooth/hci_event.c:7552 hci_rx_work+0x43a/0xd60 net/bluetooth/hci_core.c:4017 process_one_work kernel/workqueue.c:2657 [inline] process_scheduled_works+0xa60/0x1600 kernel/workqueue.c:2734 worker_thread+0xa5e/0xfe0 kernel/workqueue.c:2815 kthread+0x2fa/0x390 kernel/kthread.c:388 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293 -> #1 (hci_cb_list_lock){+.+.}-{3:3}: __mutex_lock_common kernel/locking/mutex.c:603 [inline] __mutex_lock+0x135/0xc80 kernel/locking/mutex.c:747 hci_connect_cfm include/net/bluetooth/hci_core.h:2001 [inline] hci_remote_features_evt+0x535/0x900 net/bluetooth/hci_event.c:3719 hci_event_func net/bluetooth/hci_event.c:7500 [inline] hci_event_packet+0x807/0x1280 net/bluetooth/hci_event.c:7552 hci_rx_work+0x43a/0xd60 net/bluetooth/hci_core.c:4017 process_one_work kernel/workqueue.c:2657 [inline] process_scheduled_works+0xa60/0x1600 kernel/workqueue.c:2734 worker_thread+0xa5e/0xfe0 kernel/workqueue.c:2815 kthread+0x2fa/0x390 kernel/kthread.c:388 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293 -> #0 (&hdev->lock){+.+.}-{3:3}: check_prev_add kernel/locking/lockdep.c:3162 [inline] check_prevs_add kernel/locking/lockdep.c:3281 [inline] validate_chain kernel/locking/lockdep.c:3897 [inline] __lock_acquire+0x3a07/0x7eb0 kernel/locking/lockdep.c:5171 lock_acquire+0x19e/0x420 kernel/locking/lockdep.c:5790 __mutex_lock_common kernel/locking/mutex.c:603 [inline] __mutex_lock+0x135/0xc80 kernel/locking/mutex.c:747 l2cap_chan_connect+0xfc/0xe30 net/bluetooth/l2cap_core.c:7195 l2cap_sock_connect+0x586/0x760 net/bluetooth/l2cap_sock.c:257 kernel_connect+0x142/0x1c0 net/socket.c:3636 rfcomm_session_create net/bluetooth/rfcomm/core.c:811 [inline] __rfcomm_dlc_open net/bluetooth/rfcomm/core.c:388 [inline] rfcomm_dlc_open+0xa1f/0xec0 net/bluetooth/rfcomm/core.c:431 rfcomm_sock_connect+0x2ed/0x600 net/bluetooth/rfcomm/sock.c:419 __sys_connect_file net/socket.c:2057 [inline] __sys_connect+0x3da/0x470 net/socket.c:2074 __do_sys_connect net/socket.c:2084 [inline] __se_sys_connect net/socket.c:2081 [inline] __x64_sys_connect+0x7a/0x90 net/socket.c:2081 do_syscall_x64 arch/x86/entry/common.c:46 [inline] do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76 entry_SYSCALL_64_after_hwframe+0x68/0xd2 other info that might help us debug this: Chain exists of: &hdev->lock --> hci_cb_list_lock --> rfcomm_mutex Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(rfcomm_mutex); lock(hci_cb_list_lock); lock(rfcomm_mutex); lock(&hdev->lock); *** DEADLOCK *** 1 lock held by syz.4.5320/27280: #0: ffffffff8f364ac8 (rfcomm_mutex){+.+.}-{3:3}, at: rfcomm_dlc_open+0x95/0xec0 net/bluetooth/rfcomm/core.c:429 stack backtrace: CPU: 0 PID: 27280 Comm: syz.4.5320 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2026 Call Trace: dump_stack_lvl+0x18c/0x250 lib/dump_stack.c:106 check_noncircular+0x2fc/0x400 kernel/locking/lockdep.c:2215 check_prev_add kernel/locking/lockdep.c:3162 [inline] check_prevs_add kernel/locking/lockdep.c:3281 [inline] validate_chain kernel/locking/lockdep.c:3897 [inline] __lock_acquire+0x3a07/0x7eb0 kernel/locking/lockdep.c:5171 lock_acquire+0x19e/0x420 kernel/locking/lockdep.c:5790 __mutex_lock_common kernel/locking/mutex.c:603 [inline] __mutex_lock+0x135/0xc80 kernel/locking/mutex.c:747 l2cap_chan_connect+0xfc/0xe30 net/bluetooth/l2cap_core.c:7195 l2cap_sock_connect+0x586/0x760 net/bluetooth/l2cap_sock.c:257 kernel_connect+0x142/0x1c0 net/socket.c:3636 rfcomm_session_create net/bluetooth/rfcomm/core.c:811 [inline] __rfcomm_dlc_open net/bluetooth/rfcomm/core.c:388 [inline] rfcomm_dlc_open+0xa1f/0xec0 net/bluetooth/rfcomm/core.c:431 rfcomm_sock_connect+0x2ed/0x600 net/bluetooth/rfcomm/sock.c:419 __sys_connect_file net/socket.c:2057 [inline] __sys_connect+0x3da/0x470 net/socket.c:2074 __do_sys_connect net/socket.c:2084 [inline] __se_sys_connect net/socket.c:2081 [inline] __x64_sys_connect+0x7a/0x90 net/socket.c:2081 do_syscall_x64 arch/x86/entry/common.c:46 [inline] do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76 entry_SYSCALL_64_after_hwframe+0x68/0xd2 RIP: 0033:0x7f939219e1d9 Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f9393137028 EFLAGS: 00000246 ORIG_RAX: 000000000000002a RAX: ffffffffffffffda RBX: 00007f9392425fa0 RCX: 00007f939219e1d9 RDX: 000000000000000a RSI: 0000200000001b40 RDI: 0000000000000004 RBP: 00007f9392235888 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f9392426038 R14: 00007f9392425fa0 R15: 00007fff4e0b2f08 hci2: dst 11:aa:aa:aa:aa:aa hci2: dst 11:aa:aa:aa:aa:aa handle 0x0f00 hci2 orig refcnt 13 hci2: conn ffff88802262e000 hcon ffff88802262e000 orig refcnt 0 hci2 hcon ffff88802262e000 hcon ffff88802262e000 conn ffff888141363000 hchan ffff88805efb4700 conn ffff888141363000, psm 0x03, dcid 0x0000 chan ffff88805c259000 orig refcnt 1 hcon ffff88802262e000 orig refcnt 1 hcon ffff88802262e000 orig refcnt 2 chan ffff88805c259000 BT_BOUND -> BT_CONNECT chan ffff88805c259000 state BT_CONNECT timeout 4000 chan ffff88805c259000 orig refcnt 2 hci2 orig refcnt 14 sk ffff88805c25c000 ffff88805cac6000 dlc ffff88805cac6000 session ffff8880627fee00 session ffff8880627fee00 state 3 dlc ffff88805cac6000 state 7 timeout 3000 sk ffff88806766d000 sock ffff8880767c9e00, sk ffff88806766d000 sock ffff8880767c9e00, sk ffff88806766d000 sk ffff88806766d000 state 5 socket ffff8880767c9e00 dlc ffff88805cac6000 state 7 dlci 18 err 0 dlc ffff88805cac6000 state 7 dlci 18 err 0 session ffff8880627fee00 dlc ffff88805cac6000 state 7 dlc ffff88805cac6000 state 9 err 0 dlc ffff88805cac6000 refcnt 2 session ffff8880627fee00 session ffff8880627fee00 state 3 timeout 200 sk ffff88806766d000 state 9 refcnt 2 sk ffff88806766d000 dlc ffff88805cac6000 ffff88805cac6000 kcov: kcov_task_exit: t = ffff888029fb1e00, kcov->t = ffff888029fb1e00 ffff88803138c000 name hci3 bus 0 hci3 ffff88803138c000 hci3: hci3: err 0x13 hci3: cancelling interleave scan hci3 state 0 -> 0 All LE pending actions cleared hdev hci3 hcon ffff888024922000 reason 22 hcon ffff888024922000 conn ffff888030c62800, err 103 hci3 hcon ffff888024922000 chan ffff888067699a00 hci3 hcon ffff888024922000 handle 200 hci3: hcon ffff888024922000 hcon ffff888024922000 hci3: conn ffff888024922000 device: 'hci3:200': device_unregister kernfs runtime_status: removing kernfs control: removing kernfs runtime_suspended_time: removing kernfs runtime_active_time: removing kernfs autosuspend_delay_ms: removing kernfs power: removing kernfs device: removing kernfs subsystem: removing kernfs hci3:200: removing kernfs uevent: removing PM: Removing info for No Bus:hci3:200 kobject: 'hci3:200' (ffff8880249225f0): kobject_uevent_env kobject: 'hci3:200' (ffff8880249225f0): fill_kobj_path: path = '/devices/virtual/bluetooth/hci3/hci3:200' kernfs hci3:200: removing kobject: 'hci3:200' (ffff8880249225f0): kobject_cleanup, parent 0000000000000000 kobject: 'hci3:200' (ffff8880249225f0): calling ktype release kobject: 'hci3:200': free name hci3 orig refcnt 10 hcon ffff88806684a000 reason 22 hcon ffff88806684a000 conn ffff888030c64000, err 103 hci3 hcon ffff88806684a000 chan ffff8880668fe100 hci3 hcon ffff88806684a000 handle 201 hci3: hcon ffff88806684a000 hcon ffff88806684a000 hci3: conn ffff88806684a000 device: 'hci3:201': device_unregister kernfs runtime_status: removing kernfs control: removing kernfs runtime_suspended_time: removing kernfs runtime_active_time: removing kernfs autosuspend_delay_ms: removing kernfs power: removing kernfs device: removing kernfs subsystem: removing kernfs hci3:201: removing kernfs uevent: removing PM: Removing info for No Bus:hci3:201 kobject: 'hci3:201' (ffff88806684a5f0): kobject_uevent_env kobject: 'hci3:201' (ffff88806684a5f0): fill_kobj_path: path = '/devices/virtual/bluetooth/hci3/hci3:201' kernfs hci3:201: removing kobject: 'hci3:201' (ffff88806684a5f0): kobject_cleanup, parent 0000000000000000 kobject: 'hci3:201' (ffff88806684a5f0): calling ktype release kobject: 'hci3:201': free name hci3 orig refcnt 7 hdev hci3 event 4 hdev 0000000000000000 len 8 hci3: Cleanup of MSFT extension hdev hci3 event 8 hci3 orig refcnt 6 channel 3 len 6 channel 3 len 8 hdev hci3 event 2 hdev 0000000000000000 len 8 kernfs runtime_status: removing kernfs control: removing kernfs runtime_suspended_time: removing kernfs runtime_active_time: removing kernfs autosuspend_delay_ms: removing kernfs power: removing kernfs device: removing kernfs subsystem: removing kernfs rfkill83: removing kernfs uevent: removing kernfs name: removing kernfs type: removing kernfs index: removing kernfs persistent: removing kernfs state: removing kernfs soft: removing kernfs hard: removing kernfs hard_block_reasons: removing PM: Removing info for No Bus:rfkill83 kobject: 'rfkill83' (ffff8880401d7110): kobject_uevent_env kobject: 'rfkill83' (ffff8880401d7110): fill_kobj_path: path = '/devices/virtual/bluetooth/hci3/rfkill83' kernfs rfkill83: removing kobject: 'rfkill83' (ffff8880401d7110): kobject_cleanup, parent 0000000000000000 kobject: 'rfkill83' (ffff8880401d7110): calling ktype release kobject: 'rfkill83': free name kernfs runtime_status: removing kernfs control: removing kernfs runtime_suspended_time: removing kernfs runtime_active_time: removing kernfs autosuspend_delay_ms: removing kernfs power: removing kernfs subsystem: removing kernfs hci3: removing kernfs uevent: removing PM: Removing info for No Bus:hci3 kobject: 'hci3' (ffff88803138d490): kobject_uevent_env kobject: 'hci3' (ffff88803138d490): fill_kobj_path: path = '/devices/virtual/bluetooth/hci3' kernfs hci3: removing hci3 orig refcnt 2 kobject: 'hci3' (ffff88803138d490): kobject_cleanup, parent 0000000000000000 kobject: 'hci3' (ffff88803138d490): calling ktype release All LE connection parameters were removed hci3: Unregister MSFT extension kobject: 'hci3': free name