[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 19.244142] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 23.930972] random: sshd: uninitialized urandom read (32 bytes read) [ 24.448842] random: sshd: uninitialized urandom read (32 bytes read) [ 25.210902] random: sshd: uninitialized urandom read (32 bytes read) [ 299.817668] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.2' (ECDSA) to the list of known hosts. [ 305.294793] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program [ 436.285022] INFO: rcu_sched self-detected stall on CPU [ 436.290428] 1-....: (124999 ticks this GP) idle=55a/1/4611686018427387906 softirq=11550/11550 fqs=31230 [ 436.300192] (t=125000 jiffies g=5748 c=5747 q=7) [ 436.305102] NMI backtrace for cpu 1 [ 436.308706] CPU: 1 PID: 40 Comm: kworker/u4:2 Not tainted 4.17.0-rc3+ #32 [ 436.315606] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 436.325067] Workqueue: events_unbound flush_to_ldisc [ 436.330166] Call Trace: [ 436.332727] [ 436.334911] dump_stack+0x1b9/0x294 [ 436.338521] ? dump_stack_print_info.cold.2+0x52/0x52 [ 436.343735] ? lock_release+0xa10/0xa10 [ 436.347708] nmi_cpu_backtrace.cold.4+0x19/0xce [ 436.352377] ? lapic_can_unplug_cpu.cold.26+0x3f/0x3f [ 436.357554] nmi_trigger_cpumask_backtrace+0x151/0x192 [ 436.362811] arch_trigger_cpumask_backtrace+0x14/0x20 [ 436.368001] rcu_dump_cpu_stacks+0x175/0x1c2 [ 436.372428] ? __sanitizer_cov_trace_cmp8+0x18/0x20 [ 436.377443] check_cpu_stall.isra.61.cold.80+0x36c/0x59a [ 436.382879] ? print_other_cpu_stall+0x4a0/0x4a0 [ 436.387621] ? debug_check_no_locks_freed+0x310/0x310 [ 436.392794] ? find_held_lock+0x36/0x1c0 [ 436.396840] ? lock_downgrade+0x8e0/0x8e0 [ 436.400968] ? lock_release+0xa10/0xa10 [ 436.404919] ? graph_lock+0x170/0x170 [ 436.408700] ? graph_lock+0x170/0x170 [ 436.412477] ? graph_lock+0x170/0x170 [ 436.416259] ? __sanitizer_cov_trace_const_cmp4+0x16/0x20 [ 436.421817] ? pvclock_gtod_notify+0x2db/0x3c0 [ 436.426379] ? graph_lock+0x170/0x170 [ 436.430159] ? graph_lock+0x170/0x170 [ 436.433944] ? __lock_is_held+0xb5/0x140 [ 436.437991] rcu_check_callbacks+0x21b/0xad0 [ 436.442382] ? rcu_cpu_stall_reset+0x210/0x210 [ 436.446942] ? trace_hardirqs_off+0xd/0x10 [ 436.451188] ? raise_softirq+0x1b2/0x450 [ 436.455239] ? raise_softirq_irqoff+0x310/0x310 [ 436.459904] ? account_guest_time+0x3d0/0x3d0 [ 436.464378] ? __sanitizer_cov_trace_const_cmp1+0x1a/0x20 [ 436.469895] ? hrtimer_run_queues+0x70/0x390 [ 436.474291] ? run_local_timers+0x168/0x1d0 [ 436.478590] ? timer_clear_idle+0x50/0x50 [ 436.482718] ? account_system_time+0x7f/0xb0 [ 436.487104] ? account_process_tick+0x76/0x240 [ 436.491667] update_process_times+0x2d/0x70 [ 436.496001] tick_sched_handle+0x9f/0x180 [ 436.500136] tick_sched_timer+0x45/0x130 [ 436.504175] __hrtimer_run_queues+0x3e3/0x10a0 [ 436.508737] ? tick_sched_do_timer+0x1a0/0x1a0 [ 436.513299] ? hrtimer_start_range_ns+0xd10/0xd10 [ 436.518145] ? pvclock_read_flags+0x160/0x160 [ 436.522617] ? kvm_clock_read+0x25/0x30 [ 436.526569] ? __sanitizer_cov_trace_cmp4+0x16/0x20 [ 436.531566] ? kvm_clock_read+0x25/0x30 [ 436.535519] ? __sanitizer_cov_trace_cmp4+0x16/0x20 [ 436.540516] ? ktime_get_update_offsets_now+0x3d3/0x5c0 [ 436.545866] ? do_timer+0x50/0x50 [ 436.549298] ? rcu_nmi_exit+0xd7/0x2b0 [ 436.553166] ? do_raw_spin_lock+0xc1/0x200 [ 436.557644] hrtimer_interrupt+0x2f3/0x750 [ 436.561887] smp_apic_timer_interrupt+0x15d/0x710 [ 436.566710] ? smp_call_function_single_interrupt+0x650/0x650 [ 436.572570] ? _raw_spin_lock+0x32/0x40 [ 436.576526] ? _raw_spin_unlock+0x22/0x30 [ 436.580673] ? handle_edge_irq+0x330/0x870 [ 436.584890] ? task_prio+0x50/0x50 [ 436.588432] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 436.593256] apic_timer_interrupt+0xf/0x20 [ 436.597462] [ 436.599705] RIP: 0010:__process_echoes+0x272/0x8d0 [ 436.604610] RSP: 0018:ffff8801d958f2a8 EFLAGS: 00000293 ORIG_RAX: ffffffffffffff13 [ 436.612296] RAX: ffff8801d9580280 RBX: 00000002c88f0eea RCX: ffffffff8397bdf9 [ 436.619545] RDX: 0000000000000000 RSI: fffffffd37711a37 RDI: 0000000000000edf [ 436.626793] RBP: ffff8801d958f310 R08: ffff8801d9580280 R09: 0000000000000006 [ 436.634042] R10: ffff8801d9580280 R11: 0000000000000000 R12: ffffc90002e4a000 [ 436.641291] R13: 0000000000002921 R14: fffffffd37711a37 R15: 00000000000000ff [ 436.648546] ? __process_echoes+0x249/0x8d0 [ 436.652856] ? __process_echoes+0x264/0x8d0 [ 436.657163] n_tty_receive_buf_common+0x11d5/0x2c50 [ 436.662213] ? save_stack+0x43/0xd0 [ 436.665836] ? __kasan_slab_free+0x11a/0x170 [ 436.670243] ? n_tty_receive_char_lnext+0x710/0x710 [ 436.675245] ? lock_release+0xa10/0xa10 [ 436.679205] ? trace_hardirqs_off+0xd/0x10 [ 436.683418] ? _raw_spin_unlock_irqrestore+0x63/0xc0 [ 436.688560] ? debug_check_no_obj_freed+0x2ff/0x584 [ 436.693558] n_tty_receive_buf2+0x33/0x40 [ 436.697688] tty_ldisc_receive_buf+0xb0/0x190 [ 436.702163] ? n_tty_receive_buf_common+0x2c50/0x2c50 [ 436.707331] tty_port_default_receive_buf+0x110/0x170 [ 436.712498] ? tty_port_lower_dtr_rts+0x90/0x90 [ 436.717144] ? trace_hardirqs_on+0xd/0x10 [ 436.721271] ? tty_buffer_free+0x123/0x160 [ 436.725483] flush_to_ldisc+0x3e9/0x560 [ 436.729440] ? tty_buffer_free+0x160/0x160 [ 436.733656] ? __lock_is_held+0xb5/0x140 [ 436.737734] process_one_work+0xc1e/0x1b50 [ 436.741968] ? finish_task_switch+0x28b/0x810 [ 436.746445] ? pwq_dec_nr_in_flight+0x490/0x490 [ 436.751095] ? __schedule+0x809/0x1e30 [ 436.754966] ? trace_hardirqs_on_caller+0x421/0x5c0 [ 436.759961] ? graph_lock+0x170/0x170 [ 436.763742] ? retint_kernel+0x10/0x10 [ 436.767613] ? find_held_lock+0x36/0x1c0 [ 436.771652] ? lock_acquire+0x1dc/0x520 [ 436.775604] ? worker_thread+0x41f/0x1440 [ 436.779731] ? lock_downgrade+0x8e0/0x8e0 [ 436.783862] ? lock_release+0xa10/0xa10 [ 436.787815] ? kasan_check_read+0x11/0x20 [ 436.791944] ? do_raw_spin_trylock+0x1b0/0x1b0 [ 436.796506] worker_thread+0x1cc/0x1440 [ 436.800463] ? process_one_work+0x1b50/0x1b50 [ 436.804954] ? graph_lock+0x170/0x170 [ 436.808738] ? find_held_lock+0x36/0x1c0 [ 436.812786] ? __schedule+0x1e30/0x1e30 [ 436.816741] ? do_raw_spin_unlock+0x9e/0x2e0 [ 436.821127] ? do_raw_spin_trylock+0x1b0/0x1b0 [ 436.825696] ? _raw_spin_unlock_irqrestore+0x74/0xc0 [ 436.830777] ? trace_hardirqs_on_caller+0x421/0x5c0 [ 436.835776] ? __sanitizer_cov_trace_const_cmp8+0x18/0x20 [ 436.841291] ? __kthread_parkme+0x1b7/0x280 [ 436.845591] kthread+0x345/0x410 [ 436.848934] ? process_one_work+0x1b50/0x1b50 [ 436.853405] ? kthread_bind+0x40/0x40 [ 436.857184] ret_from_fork+0x3a/0x50