====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Not tainted ------------------------------------------------------ syz.1.738/8627 is trying to acquire lock: ffff8880241a2120 (sk_lock-AF_BLUETOOTH-BTPROTO_SCO){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1744 [inline] ffff8880241a2120 (sk_lock-AF_BLUETOOTH-BTPROTO_SCO){+.+.}-{0:0}, at: sco_conn_del+0x13e/0x350 net/bluetooth/sco.c:206 but task is already holding lock: ffffffff8e3946c8 (hci_cb_list_lock){+.+.}-{3:3}, at: hci_disconn_cfm include/net/bluetooth/hci_core.h:1519 [inline] ffffffff8e3946c8 (hci_cb_list_lock){+.+.}-{3:3}, at: hci_conn_hash_flush+0xa4/0x220 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+0x1e5/0x2400 kernel/locking/mutex.c:596 __mutex_lock kernel/locking/mutex.c:729 [inline] mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743 hci_connect_cfm include/net/bluetooth/hci_core.h:1504 [inline] hci_remote_features_evt+0x5d9/0xa10 net/bluetooth/hci_event.c:3367 hci_event_packet+0x600/0x1310 net/bluetooth/hci_event.c:6455 hci_rx_work+0x255/0xa10 net/bluetooth/hci_core.c:5190 process_one_work+0x867/0xff0 kernel/workqueue.c:2310 worker_thread+0xad7/0x12a0 kernel/workqueue.c:2457 kthread+0x42e/0x520 kernel/kthread.c:334 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287 -> #1 (&hdev->lock){+.+.}-{3:3}: __mutex_lock_common+0x1e5/0x2400 kernel/locking/mutex.c:596 __mutex_lock kernel/locking/mutex.c:729 [inline] mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743 sco_sock_connect+0x189/0x940 net/bluetooth/sco.c:608 __sys_connect_file net/socket.c:1933 [inline] __sys_connect+0x3cb/0x450 net/socket.c:1950 __do_sys_connect net/socket.c:1960 [inline] __se_sys_connect net/socket.c:1957 [inline] __x64_sys_connect+0x76/0x80 net/socket.c:1957 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x66/0xd0 -> #0 (sk_lock-AF_BLUETOOTH-BTPROTO_SCO){+.+.}-{0:0}: check_prev_add kernel/locking/lockdep.c:3120 [inline] check_prevs_add kernel/locking/lockdep.c:3239 [inline] validate_chain kernel/locking/lockdep.c:3855 [inline] __lock_acquire+0x38f7/0x7d40 kernel/locking/lockdep.c:5120 lock_acquire+0x19f/0x400 kernel/locking/lockdep.c:5737 lock_sock_nested+0x44/0x100 net/core/sock.c:3258 lock_sock include/net/sock.h:1744 [inline] sco_conn_del+0x13e/0x350 net/bluetooth/sco.c:206 hci_disconn_cfm include/net/bluetooth/hci_core.h:1522 [inline] hci_conn_hash_flush+0x107/0x220 net/bluetooth/hci_conn.c:1622 hci_dev_do_close+0x918/0x1020 net/bluetooth/hci_core.c:1813 hci_unregister_dev+0x2eb/0x590 net/bluetooth/hci_core.c:4070 vhci_release+0x73/0xc0 drivers/bluetooth/hci_vhci.c:345 __fput+0x212/0x8c0 fs/file_table.c:311 task_work_run+0x125/0x1a0 kernel/task_work.c:188 exit_task_work include/linux/task_work.h:33 [inline] do_exit+0x635/0x2110 kernel/exit.c:890 do_group_exit+0x12c/0x2f0 kernel/exit.c:1004 get_signal+0x7eb/0x12e0 kernel/signal.c:2913 arch_do_signal_or_restart+0xe6/0x12a0 arch/x86/kernel/signal.c:867 handle_signal_work kernel/entry/common.c:157 [inline] exit_to_user_mode_loop+0x9e/0x130 kernel/entry/common.c:181 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:217 __syscall_exit_to_user_mode_work kernel/entry/common.c:299 [inline] syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:310 ret_from_fork+0x15/0x30 arch/x86/entry/entry_64.S:280 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.1.738/8627: #0: ffff88807a2d53f0 (&hdev->req_lock){+.+.}-{3:3}, at: hci_dev_do_close+0x5f/0x1020 net/bluetooth/hci_core.c:1755 #1: ffff88807a2d4478 (&hdev->lock){+.+.}-{3:3}, at: hci_dev_do_close+0x408/0x1020 net/bluetooth/hci_core.c:1800 #2: ffffffff8e3946c8 (hci_cb_list_lock){+.+.}-{3:3}, at: hci_disconn_cfm include/net/bluetooth/hci_core.h:1519 [inline] #2: ffffffff8e3946c8 (hci_cb_list_lock){+.+.}-{3:3}, at: hci_conn_hash_flush+0xa4/0x220 net/bluetooth/hci_conn.c:1622 stack backtrace: CPU: 0 PID: 8627 Comm: syz.1.738 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2026 Call Trace: dump_stack_lvl+0x188/0x250 lib/dump_stack.c:106 check_noncircular+0x2f8/0x400 kernel/locking/lockdep.c:2178 check_prev_add kernel/locking/lockdep.c:3120 [inline] check_prevs_add kernel/locking/lockdep.c:3239 [inline] validate_chain kernel/locking/lockdep.c:3855 [inline] __lock_acquire+0x38f7/0x7d40 kernel/locking/lockdep.c:5120 lock_acquire+0x19f/0x400 kernel/locking/lockdep.c:5737 lock_sock_nested+0x44/0x100 net/core/sock.c:3258 lock_sock include/net/sock.h:1744 [inline] sco_conn_del+0x13e/0x350 net/bluetooth/sco.c:206 hci_disconn_cfm include/net/bluetooth/hci_core.h:1522 [inline] hci_conn_hash_flush+0x107/0x220 net/bluetooth/hci_conn.c:1622 hci_dev_do_close+0x918/0x1020 net/bluetooth/hci_core.c:1813 hci_unregister_dev+0x2eb/0x590 net/bluetooth/hci_core.c:4070 vhci_release+0x73/0xc0 drivers/bluetooth/hci_vhci.c:345 __fput+0x212/0x8c0 fs/file_table.c:311 task_work_run+0x125/0x1a0 kernel/task_work.c:188 exit_task_work include/linux/task_work.h:33 [inline] do_exit+0x635/0x2110 kernel/exit.c:890 do_group_exit+0x12c/0x2f0 kernel/exit.c:1004 get_signal+0x7eb/0x12e0 kernel/signal.c:2913 arch_do_signal_or_restart+0xe6/0x12a0 arch/x86/kernel/signal.c:867 handle_signal_work kernel/entry/common.c:157 [inline] exit_to_user_mode_loop+0x9e/0x130 kernel/entry/common.c:181 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:217 __syscall_exit_to_user_mode_work kernel/entry/common.c:299 [inline] syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:310 ret_from_fork+0x15/0x30 arch/x86/entry/entry_64.S:280 RIP: 0033:0x7ff6595e01d9 Code: Unable to access opcode bytes at RIP 0x7ff6595e01af. RSP: 002b:00007ff6577f5fd8 EFLAGS: 00000206 ORIG_RAX: 0000000000000038 RAX: 0000000000000000 RBX: 00007ff659868180 RCX: 00007ff6595e01d9 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000011 RBP: 00007ff659677888 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000000 R13: 00007ff659868218 R14: 00007ff659868180 R15: 00007ffd293d6ce8 hci4 hcon ffff88804e91a000 handle 0 hcon ffff88804e91c000 orig refcnt 1 hcon ffff88804e91a000 hci4 orig refcnt 14 hci4 hcon ffff88804e91c000 handle 0 hcon ffff88804e91c000 hci4 orig refcnt 13 hci4 hcon ffff88802b490000 chan ffff888057999800 hci4 hcon ffff88802b490000 handle 201 hcon ffff88802b490000 hci4: conn ffff88802b490000 hci4 orig refcnt 10 hci4 hcon ffff888079f62000 chan ffff888057999c00 hci4 hcon ffff888079f62000 handle 200 hcon ffff888079f62000 hci4: conn ffff888079f62000 hci4 orig refcnt 7 hdev hci4 event 4 hdev 0000000000000000 len 8 hdev hci4 event 8 hci4 orig refcnt 6 channel 3 len 6 channel 3 len 8 hdev hci4 event 2 hdev 0000000000000000 len 8 hci4 orig refcnt 2 All LE connection parameters were removed In tnode_resize ffff8880237c9320 inflate_threshold=50 threshold=25 In tnode_resize ffff8880627c2020 inflate_threshold=50 threshold=25 In tnode_resize ffff88805f902820 inflate_threshold=50 threshold=25 In tnode_resize ffff888073da3d20 inflate_threshold=50 threshold=25 In tnode_resize ffff8880210f78a0 inflate_threshold=50 threshold=25 In tnode_resize ffff8880242449a0 inflate_threshold=50 threshold=25 In tnode_resize ffff888024244ba0 inflate_threshold=50 threshold=25 trie_flush found=1 In tnode_resize ffff8880237c9320 inflate_threshold=50 threshold=25 In tnode_resize ffff8880627c2020 inflate_threshold=50 threshold=25 In tnode_resize ffff88805f902820 inflate_threshold=50 threshold=25 In tnode_resize ffff888073da3d20 inflate_threshold=50 threshold=25 In tnode_resize ffff8880210f78a0 inflate_threshold=50 threshold=25 In tnode_resize ffff8880242449a0 inflate_threshold=50 threshold=25 In tnode_resize ffff888024244ba0 inflate_threshold=50 threshold=25 trie_flush found=1 net syz_tun: siw: event 2 sctp: sctp_addr_wq_mgmt: add new entry for cmd:2, addr:fe80::a8aa:aaff:feaa:aaaa in wq:ffff888078eb5c18 sctp: sctp_addr_wq_mgmt: add new entry for cmd:2, addr:fe80::aa in wq:ffff888078eb5c18 Deleting ac141400/24 tos=0 t=ffff888026bfb530 Deleting ac1414ff/32 tos=0 t=ffff888026bfb530 Deleting ac1414aa/32 tos=0 t=ffff888026bfb530 In tnode_resize ffff888073da3d20 inflate_threshold=50 threshold=25 In tnode_resize ffff888024244ba0 inflate_threshold=50 threshold=25 sctp: sctp_addr_wq_mgmt: add new entry for cmd:2, addr:172.20.20.170 in wq:ffff888078eb5c18 net syz_tun: siw: event 6 sock ffff8880745f3000, sk ffff8880241a2000 sk ffff8880241a2000 state 9 socket ffff8880745f3000 sk ffff8880241a2000 state 9 sk ffff8880241a2000