[....] Starting OpenBSD Secure Shell server: sshd[ 19.037356] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 23.970527] random: sshd: uninitialized urandom read (32 bytes read) [ 24.401462] random: sshd: uninitialized urandom read (32 bytes read) [ 25.107673] random: sshd: uninitialized urandom read (32 bytes read) [ 390.452889] random: sshd: uninitialized urandom read (32 bytes read) [ 390.590813] sshd (4488) used greatest stack depth: 16920 bytes left Warning: Permanently added '10.128.0.63' (ECDSA) to the list of known hosts. [ 395.916660] random: sshd: uninitialized urandom read (32 bytes read) [ 532.713023] INFO: rcu_sched self-detected stall on CPU [ 532.718442] 0-....: (124999 ticks this GP) idle=862/1/4611686018427387906 softirq=10647/10647 fqs=31088 [ 532.728239] (t=125000 jiffies g=4911 c=4910 q=1) [ 532.733163] NMI backtrace for cpu 0 [ 532.736782] CPU: 0 PID: 49 Comm: kworker/u4:2 Not tainted 4.17.0-rc2+ #21 [ 532.743694] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 532.753237] Workqueue: events_unbound flush_to_ldisc [ 532.758399] Call Trace: [ 532.760970] [ 532.763186] dump_stack+0x1b9/0x294 [ 532.766813] ? dump_stack_print_info.cold.2+0x52/0x52 [ 532.772026] ? lock_release+0xa10/0xa10 [ 532.776002] nmi_cpu_backtrace.cold.4+0x19/0xce [ 532.780705] ? lapic_can_unplug_cpu.cold.26+0x3f/0x3f [ 532.785890] nmi_trigger_cpumask_backtrace+0x151/0x192 [ 532.791165] arch_trigger_cpumask_backtrace+0x14/0x20 [ 532.796406] rcu_dump_cpu_stacks+0x175/0x1c2 [ 532.800834] ? __sanitizer_cov_trace_cmp8+0x18/0x20 [ 532.805852] check_cpu_stall.isra.61.cold.80+0x36c/0x59a [ 532.811304] ? print_other_cpu_stall+0x4a0/0x4a0 [ 532.816060] ? debug_check_no_locks_freed+0x310/0x310 [ 532.821246] ? find_held_lock+0x36/0x1c0 [ 532.825309] ? lock_downgrade+0x8e0/0x8e0 [ 532.829452] ? lock_release+0xa10/0xa10 [ 532.833423] ? graph_lock+0x170/0x170 [ 532.837216] ? graph_lock+0x170/0x170 [ 532.841010] ? graph_lock+0x170/0x170 [ 532.844811] ? __sanitizer_cov_trace_const_cmp4+0x16/0x20 [ 532.850384] ? pvclock_gtod_notify+0x2db/0x3c0 [ 532.854961] ? graph_lock+0x170/0x170 [ 532.858752] ? graph_lock+0x170/0x170 [ 532.862557] ? __lock_is_held+0xb5/0x140 [ 532.866621] rcu_check_callbacks+0x21b/0xad0 [ 532.871027] ? rcu_cpu_stall_reset+0x210/0x210 [ 532.875604] ? trace_hardirqs_off+0xd/0x10 [ 532.879883] ? raise_softirq+0x1b2/0x450 [ 532.883948] ? raise_softirq_irqoff+0x310/0x310 [ 532.888653] ? account_guest_time+0x3d0/0x3d0 [ 532.893141] ? __sanitizer_cov_trace_const_cmp1+0x1a/0x20 [ 532.898694] ? hrtimer_run_queues+0x70/0x300 [ 532.903107] ? run_local_timers+0x168/0x1d0 [ 532.907424] ? timer_clear_idle+0x50/0x50 [ 532.911567] ? account_system_time+0x7f/0xb0 [ 532.915968] ? account_process_tick+0x76/0x240 [ 532.920548] update_process_times+0x2d/0x70 [ 532.924888] tick_sched_handle+0x9f/0x180 [ 532.929030] tick_sched_timer+0x45/0x130 [ 532.933085] __hrtimer_run_queues+0x3e3/0x10a0 [ 532.937668] ? tick_sched_do_timer+0x1a0/0x1a0 [ 532.942246] ? hrtimer_start_range_ns+0xd10/0xd10 [ 532.947113] ? pvclock_read_flags+0x160/0x160 [ 532.951601] ? kvm_clock_read+0x25/0x30 [ 532.955573] ? kvm_clock_read+0x25/0x30 [ 532.959542] ? __sanitizer_cov_trace_cmp4+0x16/0x20 [ 532.964555] ? ktime_get_update_offsets_now+0x3a6/0x570 [ 532.969917] ? do_timer+0x50/0x50 [ 532.973360] ? rcu_nmi_exit+0xd7/0x2b0 [ 532.977277] ? do_raw_spin_lock+0xc1/0x200 [ 532.981511] hrtimer_interrupt+0x286/0x650 [ 532.985787] smp_apic_timer_interrupt+0x15d/0x710 [ 532.990621] ? smp_call_function_single_interrupt+0x650/0x650 [ 532.996509] ? _raw_spin_lock+0x32/0x40 [ 533.000480] ? _raw_spin_unlock+0x22/0x30 [ 533.004633] ? handle_edge_irq+0x330/0x870 [ 533.008860] ? task_prio+0x50/0x50 [ 533.012431] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 533.017273] apic_timer_interrupt+0xf/0x20 [ 533.021490] [ 533.023725] RIP: 0010:__sanitizer_cov_trace_const_cmp1+0x15/0x20 [ 533.029856] RSP: 0018:ffff8801d95b7258 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13 [ 533.037560] RAX: 0000000000000000 RBX: 0000000218ab6391 RCX: ffffffff8397b039 [ 533.044820] RDX: 0000000000000000 RSI: 0000000000000082 RDI: 0000000000000001 [ 533.052077] RBP: ffff8801d95b7258 R08: ffff8801d958c4c0 R09: 0000000000000006 [ 533.059347] R10: ffff8801d958c4c0 R11: 0000000000000000 R12: ffffc90001e54000 [ 533.066606] R13: 0000000000001203 R14: 0000000000000000 R15: 00000000000000ff [ 533.073880] ? __process_echoes+0x249/0x8d0 [ 533.078200] ? __sanitizer_cov_trace_const_cmp1+0x1a/0x20 [ 533.083728] __process_echoes+0x249/0x8d0 [ 533.087877] commit_echoes+0x163/0x1d0 [ 533.091766] n_tty_receive_buf_common+0x2048/0x2c50 [ 533.096857] ? save_stack+0x43/0xd0 [ 533.100476] ? __kasan_slab_free+0x11a/0x170 [ 533.104904] ? n_tty_receive_char_lnext+0x710/0x710 [ 533.109914] ? lock_release+0xa10/0xa10 [ 533.113887] ? trace_hardirqs_off+0xd/0x10 [ 533.118114] ? _raw_spin_unlock_irqrestore+0x63/0xc0 [ 533.123275] ? debug_check_no_obj_freed+0x2ff/0x584 [ 533.128281] ? trace_hardirqs_off+0xd/0x10 [ 533.132515] n_tty_receive_buf2+0x33/0x40 [ 533.136659] tty_ldisc_receive_buf+0xb0/0x190 [ 533.141145] ? n_tty_receive_buf_common+0x2c50/0x2c50 [ 533.146331] tty_port_default_receive_buf+0x110/0x170 [ 533.151511] ? tty_port_lower_dtr_rts+0x90/0x90 [ 533.156170] ? trace_hardirqs_on+0xd/0x10 [ 533.160311] ? tty_buffer_free+0x123/0x160 [ 533.164541] flush_to_ldisc+0x3e9/0x560 [ 533.168513] ? tty_buffer_free+0x160/0x160 [ 533.172745] ? __lock_is_held+0xb5/0x140 [ 533.176850] process_one_work+0xc1e/0x1b50 [ 533.181082] ? finish_task_switch+0x182/0x810 [ 533.185576] ? pwq_dec_nr_in_flight+0x490/0x490 [ 533.190245] ? __schedule+0x809/0x1e30 [ 533.194131] ? graph_lock+0x170/0x170 [ 533.197923] ? lock_downgrade+0x8e0/0x8e0 [ 533.202084] ? find_held_lock+0x36/0x1c0 [ 533.206141] ? lock_acquire+0x1dc/0x520 [ 533.210105] ? lock_downgrade+0x8e0/0x8e0 [ 533.214246] ? lock_release+0xa10/0xa10 [ 533.218215] ? kasan_check_read+0x11/0x20 [ 533.222355] ? do_raw_spin_trylock+0x1b0/0x1b0 [ 533.226937] worker_thread+0x1cc/0x1440 [ 533.230915] ? process_one_work+0x1b50/0x1b50 [ 533.235405] ? graph_lock+0x170/0x170 [ 533.239208] ? find_held_lock+0x36/0x1c0 [ 533.243272] ? __schedule+0x1e30/0x1e30 [ 533.247245] ? do_raw_spin_unlock+0x9e/0x2e0 [ 533.251660] ? do_raw_spin_trylock+0x1b0/0x1b0 [ 533.256238] ? _raw_spin_unlock_irqrestore+0x74/0xc0 [ 533.261333] ? trace_hardirqs_on_caller+0x421/0x5c0 [ 533.266343] ? __sanitizer_cov_trace_const_cmp8+0x18/0x20 [ 533.271870] ? __kthread_parkme+0x1b7/0x280 [ 533.276184] kthread+0x345/0x410 [ 533.279544] ? process_one_work+0x1b50/0x1b50 [ 533.284029] ? kthread_bind+0x40/0x40 [ 533.287822] ret_from_fork+0x3a/0x50