[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 20.009537] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 23.891973] random: sshd: uninitialized urandom read (32 bytes read) [ 24.238404] random: sshd: uninitialized urandom read (32 bytes read) [ 25.082352] random: sshd: uninitialized urandom read (32 bytes read) [ 708.872209] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.38' (ECDSA) to the list of known hosts. [ 714.360385] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program executing program executing program executing program executing program executing program executing program [ 714.472006] EXT4-fs (sda1): re-mounted. Opts: [ 714.476865] EXT4-fs (sda1): re-mounted. Opts: [ 714.482212] EXT4-fs (sda1): re-mounted. Opts: [ 714.487151] EXT4-fs (sda1): re-mounted. Opts: [ 714.492371] EXT4-fs (sda1): re-mounted. Opts: [ 714.497621] EXT4-fs (sda1): re-mounted. Opts: [ 714.503746] EXT4-fs (sda1): re-mounted. Opts: [ 714.508667] EXT4-fs (sda1): re-mounted. Opts: executing program executing program executing program executing program executing program executing program executing program executing program [ 714.611393] EXT4-fs (sda1): re-mounted. Opts: [ 714.627933] EXT4-fs (sda1): re-mounted. Opts: 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 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 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 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 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 [ 719.472091] EXT4-fs: 459 callbacks suppressed [ 719.472101] EXT4-fs (sda1): re-mounted. Opts: [ 719.484992] EXT4-fs (sda1): re-mounted. Opts: [ 719.492938] EXT4-fs (sda1): re-mounted. Opts: [ 719.515421] EXT4-fs (sda1): re-mounted. Opts: executing program executing program executing program executing program [ 719.520365] EXT4-fs (sda1): re-mounted. Opts: [ 719.525301] EXT4-fs (sda1): re-mounted. Opts: [ 719.560542] EXT4-fs (sda1): re-mounted. Opts: executing program executing program executing program executing program executing program [ 719.587676] EXT4-fs (sda1): re-mounted. Opts: [ 719.597100] EXT4-fs (sda1): re-mounted. Opts: [ 719.608074] EXT4-fs (sda1): re-mounted. Opts: 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 [ 845.318025] INFO: rcu_sched self-detected stall on CPU [ 845.323460] 0-...!: (124709 ticks this GP) idle=616/1/4611686018427387906 softirq=15563/15563 fqs=0 [ 845.332940] (t=125000 jiffies g=7523 c=7522 q=13) [ 845.337981] rcu_sched kthread starved for 125000 jiffies! g7523 c7522 f0x0 RCU_GP_WAIT_FQS(3) ->state=0x0 ->cpu=0 [ 845.348372] RCU grace-period kthread stack dump: [ 845.353119] rcu_sched R running task 23896 9 2 0x80000000 [ 845.360359] Call Trace: [ 845.363029] __schedule+0x801/0x1e30 [ 845.366772] ? trace_hardirqs_on_caller+0x421/0x5c0 [ 845.371794] ? __sched_text_start+0x8/0x8 [ 845.375938] ? _cond_resched+0x14/0x30 [ 845.379824] ? rcu_gp_init+0x83f/0x1060 [ 845.383805] ? add_timer_on+0xa50/0xa50 [ 845.387778] ? find_held_lock+0x36/0x1c0 [ 845.391849] ? lock_downgrade+0x8e0/0x8e0 [ 845.396002] schedule+0xef/0x430 [ 845.399365] ? do_raw_spin_trylock+0x1b0/0x1b0 [ 845.403945] ? __schedule+0x1e30/0x1e30 [ 845.407917] ? trace_hardirqs_on_caller+0x421/0x5c0 [ 845.412931] ? trace_hardirqs_on+0xd/0x10 [ 845.417095] ? prepare_to_swait+0x19b/0x500 [ 845.421420] ? __lockdep_init_map+0x105/0x590 [ 845.425916] ? lockdep_init_map+0x9/0x10 [ 845.429976] ? init_timer_on_stack_key+0xb7/0xe0 [ 845.434733] schedule_timeout+0x138/0x240 [ 845.438878] ? usleep_range+0x180/0x180 [ 845.442854] ? __next_timer_interrupt+0x1a0/0x1a0 [ 845.447709] rcu_gp_kthread+0x6b5/0x1940 [ 845.451790] ? rcu_batches_completed_sched+0x10/0x10 [ 845.456891] ? trace_event_raw_event_lock+0x22/0x340 [ 845.461996] ? pick_next_task_fair+0x97c/0x1780 [ 845.466661] ? graph_lock+0x170/0x170 [ 845.470462] ? resched_curr+0x122/0x190 [ 845.474445] ? trace_event_raw_event_lock+0x20/0x340 [ 845.479557] ? lock_downgrade+0x8e0/0x8e0 [ 845.483702] ? finish_task_switch+0x182/0x840 [ 845.488223] ? kasan_check_read+0x11/0x20 [ 845.492370] ? do_raw_spin_unlock+0x9e/0x2e0 [ 845.496776] ? do_raw_spin_trylock+0x1b0/0x1b0 [ 845.501373] ? compat_start_thread+0x80/0x80 [ 845.505782] ? _raw_spin_unlock_irq+0x27/0x70 [ 845.510323] ? trace_hardirqs_on_caller+0x421/0x5c0 [ 845.515343] ? kasan_check_write+0x14/0x20 [ 845.519577] ? finish_task_switch+0x28b/0x840 [ 845.524074] ? preempt_notifier_register+0x1e0/0x1e0 [ 845.529180] ? lock_repin_lock+0x410/0x410 [ 845.533501] ? __schedule+0x809/0x1e30 [ 845.537399] ? graph_lock+0x170/0x170 [ 845.541202] ? find_held_lock+0x36/0x1c0 [ 845.545272] ? find_held_lock+0x36/0x1c0 [ 845.549362] ? __schedule+0x1e30/0x1e30 [ 845.553337] ? do_raw_spin_unlock+0x9e/0x2e0 [ 845.557744] ? do_raw_spin_trylock+0x1b0/0x1b0 [ 845.563298] ? __sanitizer_cov_trace_const_cmp8+0x18/0x20 [ 845.568840] ? parse_args.cold.15+0x1b3/0x1b3 [ 845.573333] ? trace_hardirqs_on_caller+0x421/0x5c0 [ 845.578349] ? trace_hardirqs_on+0xd/0x10 [ 845.582508] kthread+0x345/0x410 [ 845.585887] ? rcu_batches_completed_sched+0x10/0x10 [ 845.590985] ? kthread_bind+0x40/0x40 [ 845.594790] ret_from_fork+0x3a/0x50 [ 845.598517] NMI backtrace for cpu 0 [ 845.602144] CPU: 0 PID: 4498 Comm: syz-executor887 Not tainted 4.17.0-rc7+ #38 [ 845.609498] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 845.618867] Call Trace: [ 845.621510] [ 845.623700] dump_stack+0x1b9/0x294 [ 845.627329] ? dump_stack_print_info.cold.2+0x52/0x52 [ 845.632518] ? lock_release+0xa10/0xa10 [ 845.636501] nmi_cpu_backtrace.cold.4+0x19/0xce [ 845.641191] ? lapic_can_unplug_cpu.cold.26+0x3f/0x3f [ 845.646378] nmi_trigger_cpumask_backtrace+0x151/0x192 [ 845.651658] arch_trigger_cpumask_backtrace+0x14/0x20 [ 845.656846] rcu_dump_cpu_stacks+0x175/0x1c2 [ 845.661258] ? __sanitizer_cov_trace_cmp8+0x18/0x20 [ 845.666289] check_cpu_stall.isra.61.cold.80+0x36c/0x59a [ 845.671748] ? print_other_cpu_stall+0x4a0/0x4a0 [ 845.676512] ? debug_check_no_locks_freed+0x310/0x310 [ 845.681698] ? find_held_lock+0x36/0x1c0 [ 845.685762] ? perf_trace_lock_acquire+0xe3/0x980 [ 845.690617] ? graph_lock+0x170/0x170 [ 845.694412] ? perf_trace_lock+0x900/0x900 [ 845.698649] ? perf_trace_lock+0x900/0x900 [ 845.702885] ? __sanitizer_cov_trace_const_cmp4+0x16/0x20 [ 845.708425] ? pvclock_gtod_notify+0x2db/0x3c0 [ 845.713005] ? graph_lock+0x170/0x170 [ 845.716815] ? graph_lock+0x170/0x170 [ 845.720627] ? __lock_is_held+0xb5/0x140 [ 845.724699] rcu_check_callbacks+0x21b/0xad0 [ 845.729115] ? rcu_cpu_stall_reset+0x210/0x210 [ 845.733696] ? trace_hardirqs_off+0xd/0x10 [ 845.737930] ? raise_softirq+0x1b2/0x450 [ 845.741991] ? raise_softirq_irqoff+0x310/0x310 [ 845.746682] ? account_guest_time+0x3d0/0x3d0 [ 845.751179] ? __sanitizer_cov_trace_const_cmp1+0x1a/0x20 [ 845.756714] ? hrtimer_run_queues+0x70/0x390 [ 845.761159] ? run_local_timers+0x168/0x1d0 [ 845.765483] ? timer_clear_idle+0x50/0x50 [ 845.769632] ? account_system_time+0x7f/0xb0 [ 845.774039] ? account_process_tick+0x76/0x240 [ 845.778624] update_process_times+0x2d/0x70 [ 845.782947] tick_sched_handle+0x9f/0x180 [ 845.787100] tick_sched_timer+0x45/0x130 [ 845.791172] __hrtimer_run_queues+0x3e3/0x10a0 [ 845.795757] ? tick_sched_do_timer+0x1a0/0x1a0 [ 845.800341] ? hrtimer_start_range_ns+0xd10/0xd10 [ 845.805192] ? pvclock_read_flags+0x160/0x160 [ 845.809689] ? kvm_clock_read+0x25/0x30 [ 845.813662] ? __sanitizer_cov_trace_cmp4+0x16/0x20 [ 845.818680] ? kvm_clock_read+0x25/0x30 [ 845.822656] ? __sanitizer_cov_trace_cmp4+0x16/0x20 [ 845.827673] ? ktime_get_update_offsets_now+0x3d3/0x5c0 [ 845.833057] ? do_timer+0x50/0x50 [ 845.836510] ? rcu_nmi_exit+0xd7/0x2b0 [ 845.840400] ? do_raw_spin_lock+0xc1/0x200 [ 845.844640] hrtimer_interrupt+0x2f3/0x750 [ 845.848888] smp_apic_timer_interrupt+0x15d/0x710 [ 845.853733] ? smp_call_function_single_interrupt+0x650/0x650 [ 845.859763] ? _raw_spin_lock+0x32/0x40 [ 845.863759] ? _raw_spin_unlock+0x22/0x30 [ 845.867905] ? handle_edge_irq+0x330/0x870 [ 845.872150] ? task_prio+0x50/0x50 [ 845.875714] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 845.880576] apic_timer_interrupt+0xf/0x20 [ 845.884801] [ 845.887041] RIP: 0010:debug_lockdep_rcu_enabled.part.1+0x18/0x60 [ 845.893198] RSP: 0018:ffff8801d9a979c8 EFLAGS: 00000202 ORIG_RAX: ffffffffffffff13 [ 845.900909] RAX: dffffc0000000000 RBX: ffff8801b2f78000 RCX: 0000000000000000 [ 845.908177] RDX: 0000000000000004 RSI: ffff8801b2f78838 RDI: ffffffff8909c8e0 [ 845.915442] RBP: ffff8801d9a979d0 R08: 0000000000000008 R09: 0000000000000004 [ 845.922706] R10: ffff8801b2f788d8 R11: ffff8801b2f78000 R12: ffff8801c98451a0 [ 845.929972] R13: dffffc0000000000 R14: ffff8801c9845220 R15: ffff8801d9a97b50 [ 845.937269] debug_lockdep_rcu_enabled+0x77/0x90 [ 845.942023] d_walk+0x4a0/0xc80 [ 845.945305] ? d_walk+0x46a/0xc80 [ 845.948762] ? d_shrink_del+0x3b0/0x3b0 [ 845.952751] ? dget_parent+0x680/0x680 [ 845.956640] ? shrink_dentry_list+0x5a8/0x7c0 [ 845.961140] ? is_subdir+0x480/0x480 [ 845.964849] ? d_shrink_del+0x3b0/0x3b0 [ 845.968822] ? d_walk+0x1b/0xc80 [ 845.972196] shrink_dcache_parent+0x179/0x230 [ 845.976695] ? path_has_submounts+0x1a0/0x1a0 [ 845.981191] ? down_write+0x87/0x120 [ 845.984959] ? vfs_rmdir+0xe0/0x470 [ 845.988585] ? down_read+0x1b0/0x1b0 [ 845.992304] ? __sanitizer_cov_trace_const_cmp4+0x16/0x20 [ 845.997843] ? security_inode_rmdir+0xf4/0x130 [ 846.002425] vfs_rmdir+0x202/0x470 [ 846.005970] do_rmdir+0x523/0x610 [ 846.009428] ? __ia32_sys_mkdir+0x80/0x80 [ 846.013578] ? exit_to_usermode_loop+0x87/0x310 [ 846.018253] ? __sanitizer_cov_trace_const_cmp4+0x16/0x20 [ 846.023789] ? exit_to_usermode_loop+0x1ef/0x310 [ 846.028549] ? do_syscall_64+0x92/0x800 [ 846.032527] __x64_sys_rmdir+0x36/0x40 [ 846.036415] do_syscall_64+0x1b1/0x800 [ 846.040301] ? syscall_slow_exit_work+0x4f0/0x4f0 [ 846.045145] ? syscall_return_slowpath+0x5c0/0x5c0 [ 846.050078] ? syscall_return_slowpath+0x30f/0x5c0 [ 846.055011] ? entry_SYSCALL_64_after_hwframe+0x59/0xbe [ 846.060381] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 846.065231] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 846.070416] RIP: 0033:0x4413e7 [ 846.073602] RSP: 002b:00007fffb0ab7d28 EFLAGS: 00000207 ORIG_RAX: 0000000000000054 [ 846.081311] RAX: ffffffffffffffda RBX: 0000000000000065 RCX: 00000000004413e7 [ 846.088573] RDX: 0000000000000000 RSI: 00000000006cd858 RDI: 00007fffb0ab8e10 [ 846.095841] RBP: 00007fffb0ab8e10 R08: 0000000000000000 R09: 0000000000000001 [ 846.103105] R10: 0000000000000005 R11: 0000000000000207 R12: 0000000001ff98a0 [ 846.110368] R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000