Starting System Logging Service... Starting Permit User Sessions... Starting getty on tty2-tty6 if dbus and logind are not available... Starting OpenBSD Secure Shell server... [ OK ] Started System Logging Service. [ OK ] Started Permit User Sessions. [ OK ] Found device /dev/ttyS0. [ 57.109766][ T6527] sshd (6527) used greatest stack depth: 23552 bytes left [ OK ] Started OpenBSD Secure Shell server. [ OK ] Started getty on tty2-tty6 if dbus and logind are not available. [ OK ] Listening on Load/Save RF Kill Switch Status /dev/rfkill Watch. [ OK ] Started Getty on tty6. [ OK ] Started Getty on tty5. [ OK ] Started Getty on tty4. [ OK ] Started Getty on tty3. [ OK ] Started Getty on tty2. [ OK ] Started Serial Getty on ttyS0. [ OK ] Started Getty on tty1. [ OK ] Reached target Login Prompts. [ OK ] Reached target Multi-User System. [ OK ] Reached target Graphical Interface. Starting Update UTMP about System Runlevel Changes... Starting Load/Save RF Kill Switch Status... [ OK ] Started Update UTMP about System Runlevel Changes. [ OK ] Started Load/Save RF Kill Switch Status. Debian GNU/Linux 9 syzkaller ttyS0 Warning: Permanently added '10.128.1.61' (ECDSA) to the list of known hosts. executing program syzkaller login: [ 75.159583][ T27] audit: type=1400 audit(1598439079.232:8): avc: denied { execmem } for pid=6851 comm="syz-executor427" scontext=system_u:system_r:kernel_t:s0 tcontext=system_u:system_r:kernel_t:s0 tclass=process permissive=1 [ 75.164517][ T6851] [ 75.182721][ T6851] ============================================ [ 75.188968][ T6851] WARNING: possible recursive locking detected [ 75.195157][ T6851] 5.9.0-rc2-syzkaller #0 Not tainted [ 75.200932][ T6851] -------------------------------------------- [ 75.207498][ T6851] syz-executor427/6851 is trying to acquire lock: [ 75.213885][ T6851] ffff888095008098 (&sighand->siglock){....}-{2:2}, at: __lock_task_sighand+0x106/0x2d0 [ 75.224197][ T6851] [ 75.224197][ T6851] but task is already holding lock: [ 75.231984][ T6851] ffff888095008098 (&sighand->siglock){....}-{2:2}, at: force_sig_info_to_task+0x6c/0x3a0 [ 75.242430][ T6851] [ 75.242430][ T6851] other info that might help us debug this: [ 75.250635][ T6851] Possible unsafe locking scenario: [ 75.250635][ T6851] [ 75.258093][ T6851] CPU0 [ 75.261545][ T6851] ---- [ 75.265432][ T6851] lock(&sighand->siglock); [ 75.272314][ T6851] lock(&sighand->siglock); [ 75.277409][ T6851] [ 75.277409][ T6851] *** DEADLOCK *** [ 75.277409][ T6851] [ 75.285569][ T6851] May be due to missing lock nesting notation [ 75.285569][ T6851] [ 75.294050][ T6851] 3 locks held by syz-executor427/6851: [ 75.299568][ T6851] #0: ffff888095008098 (&sighand->siglock){....}-{2:2}, at: force_sig_info_to_task+0x6c/0x3a0 [ 75.310017][ T6851] #1: ffff8880950080e0 (&sighand->signalfd_wqh){....}-{2:2}, at: __wake_up_common_lock+0xb4/0x130 [ 75.320681][ T6851] #2: ffffffff89bd6900 (rcu_read_lock){....}-{1:2}, at: __lock_task_sighand+0x0/0x2d0 [ 75.330291][ T6851] [ 75.330291][ T6851] stack backtrace: [ 75.336173][ T6851] CPU: 1 PID: 6851 Comm: syz-executor427 Not tainted 5.9.0-rc2-syzkaller #0 [ 75.344811][ T6851] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 75.354837][ T6851] Call Trace: [ 75.358119][ T6851] dump_stack+0x18f/0x20d [ 75.362423][ T6851] __lock_acquire.cold+0x115/0x396 [ 75.367522][ T6851] ? lockdep_hardirqs_on_prepare+0x530/0x530 [ 75.373487][ T6851] ? lockdep_hardirqs_on_prepare+0x530/0x530 [ 75.380049][ T6851] lock_acquire+0x1f1/0xad0 [ 75.384545][ T6851] ? __lock_task_sighand+0x106/0x2d0 [ 75.389890][ T6851] ? lock_release+0x8e0/0x8e0 [ 75.394547][ T6851] ? lock_release+0x8e0/0x8e0 [ 75.399195][ T6851] ? lockdep_hardirqs_on_prepare+0x530/0x530 [ 75.405328][ T6851] ? __lock_acquire+0x2e85/0x5640 [ 75.410338][ T6851] _raw_spin_lock_irqsave+0x8c/0xc0 [ 75.415741][ T6851] ? __lock_task_sighand+0x106/0x2d0 [ 75.421135][ T6851] __lock_task_sighand+0x106/0x2d0 [ 75.426252][ T6851] ? __io_async_wake+0x34f/0x980 [ 75.431189][ T6851] task_work_add+0x1d7/0x290 [ 75.436312][ T6851] ? cpumask_weight.constprop.0+0x3f/0x3f [ 75.442488][ T6851] ? lock_is_held_type+0xbb/0xf0 [ 75.447406][ T6851] __io_async_wake+0x415/0x980 [ 75.452930][ T6851] ? do_raw_spin_lock+0x120/0x2b0 [ 75.458118][ T6851] ? io_async_task_func+0x990/0x990 [ 75.463415][ T6851] ? lock_is_held_type+0xbb/0xf0 [ 75.469499][ T6851] ? rwlock_bug.part.0+0x90/0x90 [ 75.475720][ T6851] __wake_up_common+0x147/0x650 [ 75.480855][ T6851] __wake_up_common_lock+0xd0/0x130 [ 75.486297][ T6851] ? __wake_up_common+0x650/0x650 [ 75.491388][ T6851] ? __sigqueue_alloc+0x236/0x550 [ 75.496583][ T6851] ? rcu_read_lock_sched_held+0x3a/0xb0 [ 75.507966][ T6851] ? __sigqueue_alloc+0x2e4/0x550 [ 75.512996][ T6851] __send_signal+0x75b/0xf90 [ 75.517600][ T6851] force_sig_info_to_task+0x2a0/0x3a0 [ 75.523298][ T6851] force_sig_fault+0xb0/0xf0 [ 75.528217][ T6851] ? force_sig_fault_to_task+0xe0/0xe0 [ 75.534177][ T6851] ? arch_local_irq_disable+0x50/0x50 [ 75.539659][ T6851] ? _down_write_nest_lock+0x150/0x150 [ 75.545284][ T6851] __bad_area_nosemaphore+0x32a/0x480 [ 75.550758][ T6851] do_user_addr_fault+0x852/0xbf0 [ 75.558624][ T6851] ? rcu_read_lock_sched_held+0x3a/0xb0 [ 75.564298][ T6851] exc_page_fault+0xa8/0x160 [ 75.569152][ T6851] ? asm_exc_page_fault+0x8/0x30 [ 75.574196][ T6851] asm_exc_page_fault+0x1e/0x30 [ 75.579069][ T6851] RIP: 0033:0x400d4d [ 75.582951][ T6851] 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 [ 75.603360][ T6851] RSP: 002b:00007ffffa7ff7c8 EFLAGS: 00010246 [ 75.610481][ T6851] RAX: 0000000000000000 RBX: 0000000000000004 RCX: 0000000000000000 [ 75.618924][ T6851] RDX: 0000000000000005 RSI: 0000000020ee7000 RDI: 0000000000002140 [ 75.626939][ T6851] RBP: 00000000006ca018 R08: 0000000000000100 R09: 0000000000000000 [ 75.635480][ T6851] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000401d20 [ 75.643904][ T6851] R13: 0000000000401db0 R14: 0000000000000000 R15: 0000000000000000