======================================================
WARNING: possible circular locking dependency detected
5.15.183-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor/6556 is trying to acquire lock:
ffff0000ec9bb120 (sk_lock-AF_BLUETOOTH-BTPROTO_SCO){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1694 [inline]
ffff0000ec9bb120 (sk_lock-AF_BLUETOOTH-BTPROTO_SCO){+.+.}-{0:0}, at: sco_conn_del+0x120/0x4b8 net/bluetooth/sco.c:206

but task is already holding lock:
ffff8000163b8aa8 (hci_cb_list_lock){+.+.}-{3:3}, at: hci_disconn_cfm include/net/bluetooth/hci_core.h:1517 [inline]
ffff8000163b8aa8 (hci_cb_list_lock){+.+.}-{3:3}, at: hci_conn_hash_flush+0xb0/0x214 net/bluetooth/hci_conn.c:1622

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #2 (hci_cb_list_lock){+.+.}-{3:3}:
       __mutex_lock_common+0x194/0x1edc kernel/locking/mutex.c:596
       __mutex_lock kernel/locking/mutex.c:729 [inline]
       mutex_lock_nested+0xac/0x11c kernel/locking/mutex.c:743
       hci_connect_cfm include/net/bluetooth/hci_core.h:1502 [inline]
       hci_remote_features_evt+0x418/0x850 net/bluetooth/hci_event.c:3352
       hci_event_packet+0x560/0x11bc net/bluetooth/hci_event.c:6419
       hci_rx_work+0x1cc/0x880 net/bluetooth/hci_core.c:5160
       process_one_work+0x79c/0x1140 kernel/workqueue.c:2310
       worker_thread+0x8f4/0x101c kernel/workqueue.c:2457
       kthread+0x374/0x454 kernel/kthread.c:334
       ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:870

-> #1 (&hdev->lock){+.+.}-{3:3}:
       __mutex_lock_common+0x194/0x1edc kernel/locking/mutex.c:596
       __mutex_lock kernel/locking/mutex.c:729 [inline]
       mutex_lock_nested+0xac/0x11c kernel/locking/mutex.c:743
       sco_sock_connect+0x160/0x7d8 net/bluetooth/sco.c:597
       __sys_connect_file net/socket.c:1923 [inline]
       __sys_connect+0x264/0x28c net/socket.c:1940
       __do_sys_connect net/socket.c:1950 [inline]
       __se_sys_connect net/socket.c:1947 [inline]
       __arm64_sys_connect+0x7c/0x94 net/socket.c:1947
       __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
       invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:52
       el0_svc_common+0x1fc/0x258 arch/arm64/kernel/syscall.c:142
       do_el0_svc+0x58/0x14c arch/arm64/kernel/syscall.c:181
       el0_svc+0x78/0x1e0 arch/arm64/kernel/entry-common.c:608
       el0t_64_sync_handler+0xcc/0xe4 arch/arm64/kernel/entry-common.c:626
       el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584

-> #0 (sk_lock-AF_BLUETOOTH-BTPROTO_SCO){+.+.}-{0:0}:
       check_prev_add kernel/locking/lockdep.c:3053 [inline]
       check_prevs_add kernel/locking/lockdep.c:3172 [inline]
       validate_chain kernel/locking/lockdep.c:3788 [inline]
       __lock_acquire+0x2928/0x651c kernel/locking/lockdep.c:5012
       lock_acquire+0x1f4/0x620 kernel/locking/lockdep.c:5623
       lock_sock_nested+0xd8/0x1d4 net/core/sock.c:3251
       lock_sock include/net/sock.h:1694 [inline]
       sco_conn_del+0x120/0x4b8 net/bluetooth/sco.c:206
       sco_disconn_cfm+0x8c/0xdc net/bluetooth/sco.c:1216
       hci_disconn_cfm include/net/bluetooth/hci_core.h:1520 [inline]
       hci_conn_hash_flush+0x108/0x214 net/bluetooth/hci_conn.c:1622
       hci_dev_do_close+0x7e4/0x105c net/bluetooth/hci_core.c:1795
       hci_unregister_dev+0x23c/0x4c0 net/bluetooth/hci_core.c:4040
       vhci_release+0x74/0xc4 drivers/bluetooth/hci_vhci.c:345
       __fput+0x1c0/0x7f8 fs/file_table.c:311
       ____fput+0x20/0x30 fs/file_table.c:339
       task_work_run+0x12c/0x1e0 kernel/task_work.c:188
       exit_task_work include/linux/task_work.h:33 [inline]
       do_exit+0x67c/0x1f58 kernel/exit.c:874
       do_group_exit+0x100/0x268 kernel/exit.c:996
       get_signal+0x73c/0x1340 kernel/signal.c:2900
       do_signal arch/arm64/kernel/signal.c:893 [inline]
       do_notify_resume+0x35c/0x3128 arch/arm64/kernel/signal.c:946
       prepare_exit_to_user_mode arch/arm64/kernel/entry-common.c:133 [inline]
       exit_to_user_mode arch/arm64/kernel/entry-common.c:138 [inline]
       el0_svc+0xf0/0x1e0 arch/arm64/kernel/entry-common.c:609
       el0t_64_sync_handler+0xcc/0xe4 arch/arm64/kernel/entry-common.c:626
       el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584

other info that might help us debug this:

Chain exists of:
  sk_lock-AF_BLUETOOTH-BTPROTO_SCO --> &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(sk_lock-AF_BLUETOOTH-BTPROTO_SCO);

 *** DEADLOCK ***

3 locks held by syz-executor/6556:
 #0: ffff0000e0270ff0 (&hdev->req_lock){+.+.}-{3:3}, at: hci_dev_do_close+0x60/0x105c net/bluetooth/hci_core.c:1737
 #1: ffff0000e0270078 (&hdev->lock){+.+.}-{3:3}, at: hci_dev_do_close+0x334/0x105c net/bluetooth/hci_core.c:1782
 #2: ffff8000163b8aa8 (hci_cb_list_lock){+.+.}-{3:3}, at: hci_disconn_cfm include/net/bluetooth/hci_core.h:1517 [inline]
 #2: ffff8000163b8aa8 (hci_cb_list_lock){+.+.}-{3:3}, at: hci_conn_hash_flush+0xb0/0x214 net/bluetooth/hci_conn.c:1622

stack backtrace:
CPU: 1 PID: 6556 Comm: syz-executor Not tainted 5.15.183-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/19/2025
Call trace:
 dump_backtrace+0x0/0x43c arch/arm64/kernel/stacktrace.c:152
 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:216
 __dump_stack+0x30/0x40 lib/dump_stack.c:88
 dump_stack_lvl+0xf8/0x160 lib/dump_stack.c:106
 dump_stack+0x1c/0x5c lib/dump_stack.c:113
 print_circular_bug+0x148/0x1b0 kernel/locking/lockdep.c:2011
 check_noncircular+0x240/0x2d4 kernel/locking/lockdep.c:2133
 check_prev_add kernel/locking/lockdep.c:3053 [inline]
 check_prevs_add kernel/locking/lockdep.c:3172 [inline]
 validate_chain kernel/locking/lockdep.c:3788 [inline]
 __lock_acquire+0x2928/0x651c kernel/locking/lockdep.c:5012
 lock_acquire+0x1f4/0x620 kernel/locking/lockdep.c:5623
 lock_sock_nested+0xd8/0x1d4 net/core/sock.c:3251
 lock_sock include/net/sock.h:1694 [inline]
 sco_conn_del+0x120/0x4b8 net/bluetooth/sco.c:206
 sco_disconn_cfm+0x8c/0xdc net/bluetooth/sco.c:1216
 hci_disconn_cfm include/net/bluetooth/hci_core.h:1520 [inline]
 hci_conn_hash_flush+0x108/0x214 net/bluetooth/hci_conn.c:1622
 hci_dev_do_close+0x7e4/0x105c net/bluetooth/hci_core.c:1795
 hci_unregister_dev+0x23c/0x4c0 net/bluetooth/hci_core.c:4040
 vhci_release+0x74/0xc4 drivers/bluetooth/hci_vhci.c:345
 __fput+0x1c0/0x7f8 fs/file_table.c:311
 ____fput+0x20/0x30 fs/file_table.c:339
 task_work_run+0x12c/0x1e0 kernel/task_work.c:188
 exit_task_work include/linux/task_work.h:33 [inline]
 do_exit+0x67c/0x1f58 kernel/exit.c:874
 do_group_exit+0x100/0x268 kernel/exit.c:996
 get_signal+0x73c/0x1340 kernel/signal.c:2900
 do_signal arch/arm64/kernel/signal.c:893 [inline]
 do_notify_resume+0x35c/0x3128 arch/arm64/kernel/signal.c:946
 prepare_exit_to_user_mode arch/arm64/kernel/entry-common.c:133 [inline]
 exit_to_user_mode arch/arm64/kernel/entry-common.c:138 [inline]
 el0_svc+0xf0/0x1e0 arch/arm64/kernel/entry-common.c:609
 el0t_64_sync_handler+0xcc/0xe4 arch/arm64/kernel/entry-common.c:626
 el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584