[ OK ] Started Getty on tty3. [ OK ] Started Getty on tty2. [ OK ] Started Getty on tty1. [ OK ] Started Serial Getty on ttyS0. [ OK ] Reached target Login Prompts. [ OK ] Reached target Multi-User System. [ OK ] Reached target Graphical Interface. Starting Update UTMP about System Runlevel Changes... [ OK ] Started Update UTMP about System Runlevel Changes. Starting Load/Save RF Kill Switch Status... Debian GNU/Linux 9 syzkaller ttyS0 Warning: Permanently added '10.128.0.79' (ECDSA) to the list of known hosts. executing program syzkaller login: [ 57.518395][ T6844] [ 57.520762][ T6844] ============================================ [ 57.526894][ T6844] WARNING: possible recursive locking detected [ 57.533235][ T6844] 5.9.0-rc2-next-20200825-syzkaller #0 Not tainted [ 57.539721][ T6844] -------------------------------------------- [ 57.545856][ T6844] syz-executor072/6844 is trying to acquire lock: [ 57.552248][ T6844] ffff88809a394bd8 (&sighand->siglock){....}-{2:2}, at: __lock_task_sighand+0x106/0x2d0 [ 57.561963][ T6844] [ 57.561963][ T6844] but task is already holding lock: [ 57.569313][ T6844] ffff88809a394bd8 (&sighand->siglock){....}-{2:2}, at: force_sig_info_to_task+0x6c/0x3a0 [ 57.579317][ T6844] [ 57.579317][ T6844] other info that might help us debug this: [ 57.587654][ T6844] Possible unsafe locking scenario: [ 57.587654][ T6844] [ 57.595084][ T6844] CPU0 [ 57.598348][ T6844] ---- [ 57.601609][ T6844] lock(&sighand->siglock); [ 57.606269][ T6844] lock(&sighand->siglock); [ 57.610862][ T6844] [ 57.610862][ T6844] *** DEADLOCK *** [ 57.610862][ T6844] [ 57.619008][ T6844] May be due to missing lock nesting notation [ 57.619008][ T6844] [ 57.627336][ T6844] 3 locks held by syz-executor072/6844: [ 57.632874][ T6844] #0: ffff88809a394bd8 (&sighand->siglock){....}-{2:2}, at: force_sig_info_to_task+0x6c/0x3a0 [ 57.643372][ T6844] #1: ffff88809a394c20 (&sighand->signalfd_wqh){....}-{2:2}, at: __wake_up_common_lock+0xb4/0x130 [ 57.654064][ T6844] #2: ffffffff89c675c0 (rcu_read_lock){....}-{1:2}, at: __lock_task_sighand+0x0/0x2d0 [ 57.663710][ T6844] [ 57.663710][ T6844] stack backtrace: [ 57.669602][ T6844] CPU: 1 PID: 6844 Comm: syz-executor072 Not tainted 5.9.0-rc2-next-20200825-syzkaller #0 [ 57.679655][ T6844] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 57.689714][ T6844] Call Trace: [ 57.693080][ T6844] dump_stack+0x18f/0x20d [ 57.697393][ T6844] __lock_acquire.cold+0x115/0x396 [ 57.702492][ T6844] ? lockdep_hardirqs_on_prepare+0x530/0x530 [ 57.708565][ T6844] ? lockdep_hardirqs_on_prepare+0x530/0x530 [ 57.714528][ T6844] lock_acquire+0x1f1/0xad0 [ 57.719017][ T6844] ? __lock_task_sighand+0x106/0x2d0 [ 57.724281][ T6844] ? lock_release+0x8e0/0x8e0 [ 57.728937][ T6844] ? lock_release+0x8e0/0x8e0 [ 57.733636][ T6844] ? lockdep_hardirqs_on_prepare+0x530/0x530 [ 57.739595][ T6844] ? __lock_acquire+0x2e85/0x5640 [ 57.744638][ T6844] _raw_spin_lock_irqsave+0x8c/0xc0 [ 57.749860][ T6844] ? __lock_task_sighand+0x106/0x2d0 [ 57.755237][ T6844] __lock_task_sighand+0x106/0x2d0 [ 57.760356][ T6844] ? __io_async_wake+0x34f/0x980 [ 57.765275][ T6844] task_work_add+0x1d7/0x290 [ 57.769845][ T6844] ? cpumask_weight.constprop.0+0x3f/0x3f [ 57.775550][ T6844] ? lock_is_held_type+0xbb/0xf0 [ 57.780503][ T6844] __io_async_wake+0x415/0x980 [ 57.785273][ T6844] ? do_raw_spin_lock+0x120/0x2b0 [ 57.790304][ T6844] ? io_async_task_func+0x990/0x990 [ 57.795571][ T6844] ? lock_is_held_type+0xbb/0xf0 [ 57.800489][ T6844] ? rwlock_bug.part.0+0x90/0x90 [ 57.805406][ T6844] __wake_up_common+0x147/0x650 [ 57.810239][ T6844] __wake_up_common_lock+0xd0/0x130 [ 57.815418][ T6844] ? __wake_up_common+0x650/0x650 [ 57.820424][ T6844] ? __sigqueue_alloc+0x236/0x550 [ 57.825431][ T6844] ? rcu_read_lock_sched_held+0x3a/0xb0 [ 57.830984][ T6844] ? __sigqueue_alloc+0x2e4/0x550 [ 57.835992][ T6844] __send_signal+0x75b/0xf90 [ 57.840565][ T6844] force_sig_info_to_task+0x2a0/0x3a0 [ 57.846032][ T6844] force_sig_fault+0xb0/0xf0 [ 57.850697][ T6844] ? force_sig_fault_to_task+0xe0/0xe0 [ 57.856137][ T6844] ? arch_local_irq_disable+0x50/0x50 [ 57.861515][ T6844] ? _down_write_nest_lock+0x150/0x150 [ 57.867010][ T6844] __bad_area_nosemaphore+0x32a/0x480 [ 57.872365][ T6844] do_user_addr_fault+0x852/0xbf0 [ 57.877410][ T6844] ? rcu_read_lock_sched_held+0x3a/0xb0 [ 57.882944][ T6844] exc_page_fault+0xa8/0x160 [ 57.887526][ T6844] ? asm_exc_page_fault+0x8/0x30 [ 57.892449][ T6844] asm_exc_page_fault+0x1e/0x30 [ 57.897316][ T6844] RIP: 0033:0x400d4d [ 57.901229][ T6844] Code: 48 8b 54 24 e0 8b 86 0c 01 00 00 44 8b 86 08 01 00 00 c1 e0 04 8d b8 7f 01 00 00 83 e7 c0 45 85 c0 74 07 89 d0 31 d2 41 f7 f0 <4c> 8b 01 89 d0 c1 e0 06 4c 01 c8 4c 89 00 4c 8b 41 08 4c 89 40 08 [ 57.920820][ T6844] RSP: 002b:00007fffc54ce628 EFLAGS: 00010246 [ 57.926871][ T6844] RAX: 0000000000000000 RBX: 0000000000000004 RCX: 0000000000000000 [ 57.934835][ T6844] RDX: 0000000000000005 RSI: 0000000020ee7000 RDI: 0000000000002140 [ 57.942795][ T6844] RBP: 00000000006ca018 R08: 0000000000000100 R09: 0000000000000000 [ 57.950751][ T6844] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000401d20 [ 57.958746][ T6844] R13: 0000000000401db0 R14: 0000000000000000 R15: 0000000000000000