[ OK ] Started Getty on tty3. [ OK ] Reached target Login Prompts. [ OK ] Reached target Multi-User System. [ OK ] Reached target Graphical Interface. Starting Update UTMP about System Runlevel Changes... Debian GNU/Linux 9 syzkaller ttyS0 Warning: Permanently added '10.128.0.101' (ECDSA) to the list of known hosts. executing program syzkaller login: [ 59.797950][ T6828] [ 59.800289][ T6828] ============================================ [ 59.806477][ T6828] WARNING: possible recursive locking detected [ 59.812598][ T6828] 5.9.0-rc2-syzkaller #0 Not tainted [ 59.817856][ T6828] -------------------------------------------- [ 59.823971][ T6828] syz-executor510/6828 is trying to acquire lock: [ 59.830351][ T6828] ffff88809a664158 (&sighand->siglock){....}-{2:2}, at: __lock_task_sighand+0x106/0x2d0 [ 59.840044][ T6828] [ 59.840044][ T6828] but task is already holding lock: [ 59.847378][ T6828] ffff88809a664158 (&sighand->siglock){....}-{2:2}, at: force_sig_info_to_task+0x6c/0x3a0 [ 59.863962][ T6828] [ 59.863962][ T6828] other info that might help us debug this: [ 59.871989][ T6828] Possible unsafe locking scenario: [ 59.871989][ T6828] [ 59.879408][ T6828] CPU0 [ 59.882659][ T6828] ---- [ 59.885908][ T6828] lock(&sighand->siglock); [ 59.890462][ T6828] lock(&sighand->siglock); [ 59.895031][ T6828] [ 59.895031][ T6828] *** DEADLOCK *** [ 59.895031][ T6828] [ 59.903158][ T6828] May be due to missing lock nesting notation [ 59.903158][ T6828] [ 59.911533][ T6828] 3 locks held by syz-executor510/6828: [ 59.917056][ T6828] #0: ffff88809a664158 (&sighand->siglock){....}-{2:2}, at: force_sig_info_to_task+0x6c/0x3a0 [ 59.927356][ T6828] #1: ffff88809a6641a0 (&sighand->signalfd_wqh){....}-{2:2}, at: __wake_up_common_lock+0xb4/0x130 [ 59.938020][ T6828] #2: ffffffff89bd6900 (rcu_read_lock){....}-{1:2}, at: __lock_task_sighand+0x0/0x2d0 [ 59.947743][ T6828] [ 59.947743][ T6828] stack backtrace: [ 59.953606][ T6828] CPU: 0 PID: 6828 Comm: syz-executor510 Not tainted 5.9.0-rc2-syzkaller #0 [ 59.962258][ T6828] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 59.972280][ T6828] Call Trace: [ 59.975544][ T6828] dump_stack+0x18f/0x20d [ 59.979850][ T6828] __lock_acquire.cold+0x115/0x396 [ 59.984934][ T6828] ? lockdep_hardirqs_on_prepare+0x530/0x530 [ 59.990884][ T6828] ? lockdep_hardirqs_on_prepare+0x530/0x530 [ 59.996853][ T6828] lock_acquire+0x1f1/0xad0 [ 60.001327][ T6828] ? __lock_task_sighand+0x106/0x2d0 [ 60.006582][ T6828] ? lock_release+0x8e0/0x8e0 [ 60.011228][ T6828] ? lock_release+0x8e0/0x8e0 [ 60.015876][ T6828] ? lockdep_hardirqs_on_prepare+0x530/0x530 [ 60.021826][ T6828] ? __lock_acquire+0x2e85/0x5640 [ 60.026828][ T6828] _raw_spin_lock_irqsave+0x8c/0xc0 [ 60.031996][ T6828] ? __lock_task_sighand+0x106/0x2d0 [ 60.037251][ T6828] __lock_task_sighand+0x106/0x2d0 [ 60.042334][ T6828] ? __io_async_wake+0x34f/0x980 [ 60.047244][ T6828] task_work_add+0x1d7/0x290 [ 60.051815][ T6828] ? cpumask_weight.constprop.0+0x3f/0x3f [ 60.057629][ T6828] ? lock_is_held_type+0xbb/0xf0 [ 60.062536][ T6828] __io_async_wake+0x415/0x980 [ 60.067295][ T6828] ? do_raw_spin_lock+0x120/0x2b0 [ 60.072293][ T6828] ? io_async_task_func+0x990/0x990 [ 60.077477][ T6828] ? lock_is_held_type+0xbb/0xf0 [ 60.082383][ T6828] ? rwlock_bug.part.0+0x90/0x90 [ 60.087293][ T6828] __wake_up_common+0x147/0x650 [ 60.092126][ T6828] __wake_up_common_lock+0xd0/0x130 [ 60.097294][ T6828] ? __wake_up_common+0x650/0x650 [ 60.102285][ T6828] ? __sigqueue_alloc+0x236/0x550 [ 60.107295][ T6828] ? rcu_read_lock_sched_held+0x3a/0xb0 [ 60.112810][ T6828] ? __sigqueue_alloc+0x2e4/0x550 [ 60.117891][ T6828] __send_signal+0x75b/0xf90 [ 60.122453][ T6828] force_sig_info_to_task+0x2a0/0x3a0 [ 60.127795][ T6828] force_sig_fault+0xb0/0xf0 [ 60.132353][ T6828] ? force_sig_fault_to_task+0xe0/0xe0 [ 60.137784][ T6828] ? arch_local_irq_disable+0x50/0x50 [ 60.143141][ T6828] ? _down_write_nest_lock+0x150/0x150 [ 60.148590][ T6828] __bad_area_nosemaphore+0x32a/0x480 [ 60.153934][ T6828] do_user_addr_fault+0x852/0xbf0 [ 60.158932][ T6828] ? rcu_read_lock_sched_held+0x3a/0xb0 [ 60.164549][ T6828] exc_page_fault+0xa8/0x160 [ 60.169110][ T6828] ? asm_exc_page_fault+0x8/0x30 [ 60.174028][ T6828] asm_exc_page_fault+0x1e/0x30 [ 60.178847][ T6828] RIP: 0023:0x8048bfa [ 60.182996][ T6828] Code: 20 8b 83 0c 01 00 00 8b ab 08 01 00 00 c1 e0 04 8d b0 7f 01 00 00 83 e6 c0 85 ed 74 06 89 d0 31 d2 f7 f5 89 d0 c1 e0 06 01 f8 <8b> 39 89 38 8b 79 04 89 78 04 8b 79 08 89 78 08 8b 79 0c 89 78 0c [ 60.202572][ T6828] RSP: 002b:00000000ffd22b00 EFLAGS: 00010202 [ 60.208609][ T6828] RAX: 0000000000000140 RBX: 0000000020ee7000 RCX: 0000000000000000 [ 60.216550][ T6828] RDX: 0000000000000005 RSI: 0000000000002140 RDI: 0000000000000000 [ 60.224490][ T6828] RBP: 0000000000000100 R08: 0000000000000000 R09: 0000000000000000 [ 60.232443][ T6828] R10: 0000000000000000 R11: 0000000000000282 R12: 0000000000000000 [ 60.240385][ T6828] R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000