[ OK ] Reached target Multi-User System. [ OK ] Reached target Graphical Interface. Starting Update UTMP about System Runlevel Changes... [ OK ] Started Load/Save RF Kill Switch Status. [ OK ] Started Update UTMP about System Runlevel Changes. Debian GNU/Linux 9 syzkaller ttyS0 Warning: Permanently added '10.128.0.137' (ECDSA) to the list of known hosts. executing program syzkaller login: [ 63.999343][ T6850] [ 64.001677][ T6850] ============================================ [ 64.007796][ T6850] WARNING: possible recursive locking detected [ 64.013934][ T6850] 5.9.0-rc2-syzkaller #0 Not tainted [ 64.019195][ T6850] -------------------------------------------- [ 64.025331][ T6850] syz-executor334/6850 is trying to acquire lock: [ 64.031712][ T6850] ffff88809a492ad8 (&sighand->siglock){....}-{2:2}, at: __lock_task_sighand+0x106/0x2d0 [ 64.041412][ T6850] [ 64.041412][ T6850] but task is already holding lock: [ 64.048770][ T6850] ffff88809a492ad8 (&sighand->siglock){....}-{2:2}, at: force_sig_info_to_task+0x6c/0x3a0 [ 64.058640][ T6850] [ 64.058640][ T6850] other info that might help us debug this: [ 64.066679][ T6850] Possible unsafe locking scenario: [ 64.066679][ T6850] [ 64.074100][ T6850] CPU0 [ 64.077354][ T6850] ---- [ 64.080615][ T6850] lock(&sighand->siglock); [ 64.085183][ T6850] lock(&sighand->siglock); [ 64.089757][ T6850] [ 64.089757][ T6850] *** DEADLOCK *** [ 64.089757][ T6850] [ 64.097881][ T6850] May be due to missing lock nesting notation [ 64.097881][ T6850] [ 64.106176][ T6850] 3 locks held by syz-executor334/6850: [ 64.111772][ T6850] #0: ffff88809a492ad8 (&sighand->siglock){....}-{2:2}, at: force_sig_info_to_task+0x6c/0x3a0 [ 64.122080][ T6850] #1: ffff88809a492b20 (&sighand->signalfd_wqh){....}-{2:2}, at: __wake_up_common_lock+0xb4/0x130 [ 64.132735][ T6850] #2: ffffffff89bd6900 (rcu_read_lock){....}-{1:2}, at: __lock_task_sighand+0x0/0x2d0 [ 64.142345][ T6850] [ 64.142345][ T6850] stack backtrace: [ 64.148225][ T6850] CPU: 0 PID: 6850 Comm: syz-executor334 Not tainted 5.9.0-rc2-syzkaller #0 [ 64.156949][ T6850] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 64.166984][ T6850] Call Trace: [ 64.170255][ T6850] dump_stack+0x18f/0x20d [ 64.174564][ T6850] __lock_acquire.cold+0x115/0x396 [ 64.179661][ T6850] ? lockdep_hardirqs_on_prepare+0x530/0x530 [ 64.185613][ T6850] ? lockdep_hardirqs_on_prepare+0x530/0x530 [ 64.191566][ T6850] lock_acquire+0x1f1/0xad0 [ 64.196046][ T6850] ? __lock_task_sighand+0x106/0x2d0 [ 64.201319][ T6850] ? lock_release+0x8e0/0x8e0 [ 64.205968][ T6850] ? lock_release+0x8e0/0x8e0 [ 64.210639][ T6850] ? lockdep_hardirqs_on_prepare+0x530/0x530 [ 64.216592][ T6850] ? __lock_acquire+0x2e85/0x5640 [ 64.221594][ T6850] _raw_spin_lock_irqsave+0x8c/0xc0 [ 64.226771][ T6850] ? __lock_task_sighand+0x106/0x2d0 [ 64.232031][ T6850] __lock_task_sighand+0x106/0x2d0 [ 64.237899][ T6850] ? __io_async_wake+0x34f/0x980 [ 64.242822][ T6850] task_work_add+0x1d7/0x290 [ 64.247384][ T6850] ? cpumask_weight.constprop.0+0x3f/0x3f [ 64.253089][ T6850] ? lock_is_held_type+0xbb/0xf0 [ 64.258009][ T6850] __io_async_wake+0x415/0x980 [ 64.262747][ T6850] ? do_raw_spin_lock+0x120/0x2b0 [ 64.267743][ T6850] ? io_async_task_func+0x990/0x990 [ 64.272924][ T6850] ? lock_is_held_type+0xbb/0xf0 [ 64.277834][ T6850] ? rwlock_bug.part.0+0x90/0x90 [ 64.282745][ T6850] __wake_up_common+0x147/0x650 [ 64.287586][ T6850] __wake_up_common_lock+0xd0/0x130 [ 64.292768][ T6850] ? __wake_up_common+0x650/0x650 [ 64.297783][ T6850] ? __sigqueue_alloc+0x236/0x550 [ 64.302780][ T6850] ? rcu_read_lock_sched_held+0x3a/0xb0 [ 64.308301][ T6850] ? __sigqueue_alloc+0x2e4/0x550 [ 64.313297][ T6850] __send_signal+0x75b/0xf90 [ 64.317870][ T6850] force_sig_info_to_task+0x2a0/0x3a0 [ 64.323227][ T6850] force_sig_fault+0xb0/0xf0 [ 64.327800][ T6850] ? force_sig_fault_to_task+0xe0/0xe0 [ 64.333242][ T6850] ? arch_local_irq_disable+0x50/0x50 [ 64.338585][ T6850] ? _down_write_nest_lock+0x150/0x150 [ 64.344021][ T6850] __bad_area_nosemaphore+0x32a/0x480 [ 64.349457][ T6850] do_user_addr_fault+0x852/0xbf0 [ 64.354481][ T6850] ? rcu_read_lock_sched_held+0x3a/0xb0 [ 64.360003][ T6850] exc_page_fault+0xa8/0x160 [ 64.364568][ T6850] ? asm_exc_page_fault+0x8/0x30 [ 64.369485][ T6850] asm_exc_page_fault+0x1e/0x30 [ 64.374319][ T6850] RIP: 0033:0x400d4d [ 64.378198][ T6850] 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 [ 64.397780][ T6850] RSP: 002b:00007ffe66f09f48 EFLAGS: 00010246 [ 64.403831][ T6850] RAX: 0000000000000000 RBX: 0000000000000004 RCX: 0000000000000000 [ 64.411778][ T6850] RDX: 0000000000000005 RSI: 0000000020ee7000 RDI: 0000000000002140 [ 64.419724][ T6850] RBP: 00000000006ca018 R08: 0000000000000100 R09: 0000000000000000 [ 64.427675][ T6850] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000401d20 [ 64.435635][ T6850] R13: 0000000000401db0 R14: 0000000000000000 R15: 0000000000000000