======================================================
WARNING: possible circular locking dependency detected
6.14.0-rc7-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor/10399 is trying to acquire lock:
ffff88807aadc040 ((work_completion)(&(&conn->info_timer)->work)){+.+.}-{0:0}, at: touch_work_lockdep_map kernel/workqueue.c:3922 [inline]
ffff88807aadc040 ((work_completion)(&(&conn->info_timer)->work)){+.+.}-{0:0}, at: start_flush_work kernel/workqueue.c:4176 [inline]
ffff88807aadc040 ((work_completion)(&(&conn->info_timer)->work)){+.+.}-{0:0}, at: __flush_work+0x4db/0xcd0 kernel/workqueue.c:4208

but task is already holding lock:
ffff88807aadc338 (&conn->lock#2){+.+.}-{4:4}, at: l2cap_conn_del+0x7f/0x730 net/bluetooth/l2cap_core.c:1761

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&conn->lock#2){+.+.}-{4:4}:
       __mutex_lock_common kernel/locking/mutex.c:585 [inline]
       __mutex_lock+0x19b/0xb10 kernel/locking/mutex.c:730
       l2cap_info_timeout+0x79/0xa0 net/bluetooth/l2cap_core.c:1667
       process_one_work+0x9c5/0x1ba0 kernel/workqueue.c:3238
       process_scheduled_works kernel/workqueue.c:3319 [inline]
       worker_thread+0x6c8/0xf00 kernel/workqueue.c:3400
       kthread+0x3af/0x750 kernel/kthread.c:464
       ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:148
       ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

-> #0 ((work_completion)(&(&conn->info_timer)->work)){+.+.}-{0:0}:
       check_prev_add kernel/locking/lockdep.c:3163 [inline]
       check_prevs_add kernel/locking/lockdep.c:3282 [inline]
       validate_chain kernel/locking/lockdep.c:3906 [inline]
       __lock_acquire+0x249e/0x3c40 kernel/locking/lockdep.c:5228
       lock_acquire.part.0+0x11b/0x380 kernel/locking/lockdep.c:5851
       touch_work_lockdep_map kernel/workqueue.c:3922 [inline]
       start_flush_work kernel/workqueue.c:4176 [inline]
       __flush_work+0x4e5/0xcd0 kernel/workqueue.c:4208
       __cancel_work_sync+0x10c/0x130 kernel/workqueue.c:4364
       l2cap_conn_del+0x5b3/0x730 net/bluetooth/l2cap_core.c:1795
       l2cap_disconn_cfm net/bluetooth/l2cap_core.c:7264 [inline]
       l2cap_disconn_cfm+0x96/0xd0 net/bluetooth/l2cap_core.c:7257
       hci_disconn_cfm include/net/bluetooth/hci_core.h:2044 [inline]
       hci_conn_hash_flush+0x10b/0x260 net/bluetooth/hci_conn.c:2698
       hci_dev_close_sync+0x603/0x11a0 net/bluetooth/hci_sync.c:5197
       hci_dev_do_close+0x2e/0x90 net/bluetooth/hci_core.c:483
       hci_unregister_dev+0x213/0x620 net/bluetooth/hci_core.c:2678
       vhci_release+0x79/0xf0 drivers/bluetooth/hci_vhci.c:664
       __fput+0x3ff/0xb70 fs/file_table.c:464
       task_work_run+0x14e/0x250 kernel/task_work.c:227
       exit_task_work include/linux/task_work.h:40 [inline]
       do_exit+0xad8/0x2d70 kernel/exit.c:938
       do_group_exit+0xd3/0x2a0 kernel/exit.c:1087
       __do_sys_exit_group kernel/exit.c:1098 [inline]
       __se_sys_exit_group kernel/exit.c:1096 [inline]
       __x64_sys_exit_group+0x3e/0x50 kernel/exit.c:1096
       x64_sys_call+0x151f/0x1720 arch/x86/include/generated/asm/syscalls_64.h:232
       do_syscall_x64 arch/x86/entry/common.c:52 [inline]
       do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

other info that might help us debug this:

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&conn->lock#2);
                               lock((work_completion)(&(&conn->info_timer)->work));
                               lock(&conn->lock#2);
  lock((work_completion)(&(&conn->info_timer)->work));

 *** DEADLOCK ***

5 locks held by syz-executor/10399:
 #0: ffff888033f98d80 (&hdev->req_lock){+.+.}-{4:4}, at: hci_dev_do_close+0x26/0x90 net/bluetooth/hci_core.c:481
 #1: ffff888033f98078 (&hdev->lock){+.+.}-{4:4}, at: hci_dev_close_sync+0x3ab/0x11a0 net/bluetooth/hci_sync.c:5185
 #2: ffffffff90165608 (hci_cb_list_lock){+.+.}-{4:4}, at: hci_disconn_cfm include/net/bluetooth/hci_core.h:2041 [inline]
 #2: ffffffff90165608 (hci_cb_list_lock){+.+.}-{4:4}, at: hci_conn_hash_flush+0xbb/0x260 net/bluetooth/hci_conn.c:2698
 #3: ffff88807aadc338 (&conn->lock#2){+.+.}-{4:4}, at: l2cap_conn_del+0x7f/0x730 net/bluetooth/l2cap_core.c:1761
 #4: ffffffff8e1bd140 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:337 [inline]
 #4: ffffffff8e1bd140 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #4: ffffffff8e1bd140 (rcu_read_lock){....}-{1:3}, at: start_flush_work kernel/workqueue.c:4150 [inline]
 #4: ffffffff8e1bd140 (rcu_read_lock){....}-{1:3}, at: __flush_work+0x107/0xcd0 kernel/workqueue.c:4208

stack backtrace:
CPU: 0 UID: 0 PID: 10399 Comm: syz-executor Not tainted 6.14.0-rc7-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
 print_circular_bug+0x490/0x760 kernel/locking/lockdep.c:2076
 check_noncircular+0x31a/0x400 kernel/locking/lockdep.c:2208
 check_prev_add kernel/locking/lockdep.c:3163 [inline]
 check_prevs_add kernel/locking/lockdep.c:3282 [inline]
 validate_chain kernel/locking/lockdep.c:3906 [inline]
 __lock_acquire+0x249e/0x3c40 kernel/locking/lockdep.c:5228
 lock_acquire.part.0+0x11b/0x380 kernel/locking/lockdep.c:5851
 touch_work_lockdep_map kernel/workqueue.c:3922 [inline]
 start_flush_work kernel/workqueue.c:4176 [inline]
 __flush_work+0x4e5/0xcd0 kernel/workqueue.c:4208
 __cancel_work_sync+0x10c/0x130 kernel/workqueue.c:4364
 l2cap_conn_del+0x5b3/0x730 net/bluetooth/l2cap_core.c:1795
 l2cap_disconn_cfm net/bluetooth/l2cap_core.c:7264 [inline]
 l2cap_disconn_cfm+0x96/0xd0 net/bluetooth/l2cap_core.c:7257
 hci_disconn_cfm include/net/bluetooth/hci_core.h:2044 [inline]
 hci_conn_hash_flush+0x10b/0x260 net/bluetooth/hci_conn.c:2698
 hci_dev_close_sync+0x603/0x11a0 net/bluetooth/hci_sync.c:5197
 hci_dev_do_close+0x2e/0x90 net/bluetooth/hci_core.c:483
 hci_unregister_dev+0x213/0x620 net/bluetooth/hci_core.c:2678
 vhci_release+0x79/0xf0 drivers/bluetooth/hci_vhci.c:664
 __fput+0x3ff/0xb70 fs/file_table.c:464
 task_work_run+0x14e/0x250 kernel/task_work.c:227
 exit_task_work include/linux/task_work.h:40 [inline]
 do_exit+0xad8/0x2d70 kernel/exit.c:938
 do_group_exit+0xd3/0x2a0 kernel/exit.c:1087
 __do_sys_exit_group kernel/exit.c:1098 [inline]
 __se_sys_exit_group kernel/exit.c:1096 [inline]
 __x64_sys_exit_group+0x3e/0x50 kernel/exit.c:1096
 x64_sys_call+0x151f/0x1720 arch/x86/include/generated/asm/syscalls_64.h:232
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f5510d8d169
Code: Unable to access opcode bytes at 0x7f5510d8d13f.
RSP: 002b:00007ffd613a9b78 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 00007f5510e0f088 RCX: 00007f5510d8d169
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000043
RBP: 00007f5510dec638 R08: 00007ffd613a7917 R09: 000000000000002c
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000002
R13: 000000000000002c R14: 00007ffd613a9cb2 R15: 0000000000000024
 </TASK>