Bluetooth: hci1: Opcode 0x0406 failed: -4
Bluetooth: hci2: Opcode 0x0c1a failed: -4
Bluetooth: hci2: Opcode 0x0406 failed: -4
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.3.125/6383 is trying to acquire lock:
ffff88811fa08040 ((work_completion)(&(&conn->info_timer)->work)){+.+.}-{0:0}, at: __flush_work+0xd2/0xbc0

but task is already holding lock:
ffff88811fa08338 (&conn->lock#2){+.+.}-{4:4}, at: l2cap_conn_del+0x70/0x680

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&conn->lock#2){+.+.}-{4:4}:
       lock_acquire+0x120/0x360
       __mutex_lock+0x187/0x1360
       l2cap_info_timeout+0x60/0xa0
       process_scheduled_works+0xae1/0x17b0
       worker_thread+0x8a0/0xda0
       kthread+0x711/0x8a0
       ret_from_fork+0x3fc/0x770
       ret_from_fork_asm+0x1a/0x30

-> #0 ((work_completion)(&(&conn->info_timer)->work)){+.+.}-{0:0}:
       validate_chain+0xb9b/0x2140
       __lock_acquire+0xab9/0xd20
       lock_acquire+0x120/0x360
       __flush_work+0x6b8/0xbc0
       __cancel_work_sync+0xbe/0x110
       l2cap_conn_del+0x4f0/0x680
       l2cap_connect_cfm+0x11d/0x1040
       hci_conn_failed+0x1ce/0x310
       hci_abort_conn_sync+0x658/0xe30
       hci_disconnect_all_sync+0x1b5/0x350
       hci_suspend_sync+0x3b8/0xbf0
       hci_suspend_dev+0x28d/0x4d0
       hci_suspend_notifier+0xf2/0x290
       notifier_call_chain+0x1b6/0x3e0
       blocking_notifier_call_chain_robust+0x85/0x100
       pm_notifier_call_chain_robust+0x2c/0x60
       snapshot_open+0x19c/0x280
       misc_open+0x2bc/0x330
       chrdev_open+0x4cc/0x5e0
       do_dentry_open+0x953/0x13f0
       vfs_open+0x3b/0x340
       path_openat+0x2ee5/0x3830
       do_filp_open+0x1fa/0x410
       do_sys_openat2+0x121/0x1c0
       __x64_sys_openat+0x138/0x170
       do_syscall_64+0xfa/0x3b0
       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 ***

8 locks held by syz.3.125/6383:
 #0: ffffffff8e9c12c8 (misc_mtx){+.+.}-{4:4}, at: misc_open+0x51/0x330
 #1: ffffffff8dfe9e88 (system_transition_mutex){+.+.}-{4:4}, at: lock_system_sleep+0x4a/0x70
 #2: ffffffff8e00d650 ((pm_chain_head).rwsem){++++}-{4:4}, at: blocking_notifier_call_chain_robust+0x65/0x100
 #3: ffff888108234dc0 (&hdev->req_lock){+.+.}-{4:4}, at: hci_suspend_dev+0x285/0x4d0
 #4: ffff8881082340b8 (&hdev->lock){+.+.}-{4:4}, at: hci_abort_conn_sync+0x242/0xe30
 #5: ffffffff8f69c948 (hci_cb_list_lock){+.+.}-{4:4}, at: hci_conn_failed+0x165/0x310
 #6: ffff88811fa08338 (&conn->lock#2){+.+.}-{4:4}, at: l2cap_conn_del+0x70/0x680
 #7: ffffffff8e139ea0 (rcu_read_lock){....}-{1:3}, at: __flush_work+0xd2/0xbc0

stack backtrace:
CPU: 0 UID: 0 PID: 6383 Comm: syz.3.125 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250
 print_circular_bug+0x2ee/0x310
 check_noncircular+0x134/0x160
 validate_chain+0xb9b/0x2140
 __lock_acquire+0xab9/0xd20
 lock_acquire+0x120/0x360
 __flush_work+0x6b8/0xbc0
 __cancel_work_sync+0xbe/0x110
 l2cap_conn_del+0x4f0/0x680
 l2cap_connect_cfm+0x11d/0x1040
 hci_conn_failed+0x1ce/0x310
 hci_abort_conn_sync+0x658/0xe30
 hci_disconnect_all_sync+0x1b5/0x350
 hci_suspend_sync+0x3b8/0xbf0
 hci_suspend_dev+0x28d/0x4d0
 hci_suspend_notifier+0xf2/0x290
 notifier_call_chain+0x1b6/0x3e0
 blocking_notifier_call_chain_robust+0x85/0x100
 pm_notifier_call_chain_robust+0x2c/0x60
 snapshot_open+0x19c/0x280
 misc_open+0x2bc/0x330
 chrdev_open+0x4cc/0x5e0
 do_dentry_open+0x953/0x13f0
 vfs_open+0x3b/0x340
 path_openat+0x2ee5/0x3830
 do_filp_open+0x1fa/0x410
 do_sys_openat2+0x121/0x1c0
 __x64_sys_openat+0x138/0x170
 do_syscall_64+0xfa/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fcd2f38ebe9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fcd302cd038 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007fcd2f5b5fa0 RCX: 00007fcd2f38ebe9
RDX: 0000000000040000 RSI: 0000200000000680 RDI: ffffffffffffff9c
RBP: 00007fcd2f411e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000019 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fcd2f5b6038 R14: 00007fcd2f5b5fa0 R15: 00007ffd74f73328
 </TASK>
