[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 19.917696] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 23.831750] random: sshd: uninitialized urandom read (32 bytes read) [ 24.356363] random: sshd: uninitialized urandom read (32 bytes read) [ 25.119391] random: sshd: uninitialized urandom read (32 bytes read) [ 437.346423] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.40' (ECDSA) to the list of known hosts. [ 443.400304] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program executing program [ 615.391173] INFO: task syz-executor605:4489 blocked for more than 120 seconds. [ 615.398740] Not tainted 4.17.0-rc6+ #64 [ 615.403266] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [ 615.411309] syz-executor605 D22544 4489 4487 0x00000000 [ 615.417044] Call Trace: [ 615.419766] __schedule+0x801/0x1e30 [ 615.423525] ? __sched_text_start+0x8/0x8 [ 615.427787] ? do_raw_spin_trylock+0x1b0/0x1b0 [ 615.432420] ? _raw_spin_unlock_irqrestore+0x74/0xc0 [ 615.437557] ? trace_hardirqs_on_caller+0x421/0x5c0 [ 615.442605] ? trace_hardirqs_on+0xd/0x10 [ 615.446777] ? prepare_to_wait_event+0x38e/0xc50 [ 615.451567] ? prepare_to_wait_exclusive+0x540/0x540 [ 615.456690] ? find_held_lock+0x36/0x1c0 [ 615.460784] schedule+0xef/0x430 [ 615.464170] ? __schedule+0x1e30/0x1e30 [ 615.468234] ? check_same_owner+0x320/0x320 [ 615.472593] ? replenish_dl_entity.cold.53+0x37/0x37 [ 615.477743] ? __might_sleep+0x95/0x190 [ 615.481799] blk_mq_freeze_queue_wait+0x1ce/0x460 [ 615.486692] ? blk_mq_poll+0x930/0x930 [ 615.490606] ? blk_mq_run_hw_queue+0x119/0x390 [ 615.495220] ? blk_mq_run_work_fn+0x70/0x70 [ 615.499564] ? finish_wait+0x420/0x420 [ 615.503492] blk_freeze_queue+0x4a/0x80 [ 615.507486] blk_mq_freeze_queue+0x15/0x20 [ 615.511799] lo_ioctl+0xa9a/0x2130 [ 615.515368] ? lo_rw_aio_complete+0x430/0x430 [ 615.519905] blkdev_ioctl+0x9b6/0x2020 [ 615.523816] ? blkpg_ioctl+0xc40/0xc40 [ 615.527735] ? lock_downgrade+0x8e0/0x8e0 [ 615.531989] ? kasan_check_read+0x11/0x20 [ 615.536218] ? rcu_is_watching+0x85/0x140 [ 615.540400] ? rcu_pm_notify+0xc0/0xc0 [ 615.544340] ? vfs_writev+0x255/0x330 [ 615.548169] ? rcu_read_lock_sched_held+0x108/0x120 [ 615.553221] ? kfree+0x1e9/0x260 [ 615.556604] ? vfs_writev+0xfc/0x330 [ 615.560351] ? do_raw_spin_unlock+0x9e/0x2e0 [ 615.564776] ? vfs_iter_write+0xb0/0xb0 [ 615.568818] block_ioctl+0xee/0x130 [ 615.572628] ? blkdev_fallocate+0x400/0x400 [ 615.577031] do_vfs_ioctl+0x1cf/0x16a0 [ 615.580949] ? ioctl_preallocate+0x2e0/0x2e0 [ 615.585393] ? fget_raw+0x20/0x20 [ 615.588868] ? quarantine_put+0xeb/0x190 [ 615.592968] ? do_pwritev+0x167/0x270 [ 615.596832] ? security_file_ioctl+0x94/0xc0 [ 615.601283] ksys_ioctl+0xa9/0xd0 [ 615.604763] __x64_sys_ioctl+0x73/0xb0 [ 615.608722] do_syscall_64+0x1b1/0x800 [ 615.612638] ? syscall_return_slowpath+0x5c0/0x5c0 [ 615.617588] ? syscall_return_slowpath+0x30f/0x5c0 [ 615.622536] ? entry_SYSCALL_64_after_hwframe+0x59/0xbe [ 615.627921] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 615.632777] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 615.637991] RIP: 0033:0x443dd9 [ 615.641189] RSP: 002b:00007fff610abb88 EFLAGS: 00000286 ORIG_RAX: 0000000000000010 [ 615.648953] RAX: ffffffffffffffda RBX: 6f6f6c2f7665642f RCX: 0000000000443dd9 [ 615.656269] RDX: 0000000000000007 RSI: 0000000000004c06 RDI: 0000000000000007 [ 615.663578] RBP: 00000000006ce018 R08: 00000000004002e0 R09: 00000000004002e0 [ 615.670883] R10: 00000000004002e0 R11: 0000000000000286 R12: 0000000000401a80 [ 615.678179] R13: 0000000000401b10 R14: 0000000000000000 R15: 0000000000000000 [ 615.685488] [ 615.685488] Showing all locks held in the system: [ 615.691849] 2 locks held by khungtaskd/892: [ 615.696259] #0: (ptrval) (rcu_read_lock){....}, at: watchdog+0x1ff/0xf60 [ 615.704029] #1: (ptrval) (tasklist_lock){.+.+}, at: debug_show_all_locks+0xde/0x34a [ 615.712702] 2 locks held by getty/4462: [ 615.716712] #0: (ptrval) (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 [ 615.725023] #1: (ptrval) (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 [ 615.733990] 2 locks held by getty/4463: [ 615.737992] #0: (ptrval) (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 [ 615.746289] #1: (ptrval) (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 [ 615.755180] 2 locks held by getty/4464: [ 615.759182] #0: (ptrval) (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 [ 615.767462] #1: (ptrval) (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 [ 615.776345] 2 locks held by getty/4465: [ 615.780361] #0: (ptrval) (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 [ 615.788647] #1: (ptrval) (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 [ 615.797551] 2 locks held by getty/4466: [ 615.801535] #0: (ptrval) (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 [ 615.809815] #1: (ptrval) (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 [ 615.818735] 2 locks held by getty/4467: [ 615.822749] #0: (ptrval) (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 [ 615.831062] #1: (ptrval) (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 [ 615.840074] 2 locks held by getty/4468: [ 615.844112] #0: (ptrval) (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 [ 615.852446] #1: (ptrval) (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 [ 615.861353] 1 lock held by syz-executor605/4489: [ 615.866128] #0: (ptrval) (&lo->lo_ctl_mutex/1){+.+.}, at: lo_ioctl+0x8d/0x2130 [ 615.874324] [ 615.875966] ============================================= [ 615.875966] [ 615.883028] NMI backtrace for cpu 1 [ 615.886682] CPU: 1 PID: 892 Comm: khungtaskd Not tainted 4.17.0-rc6+ #64 [ 615.893499] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 615.902837] Call Trace: [ 615.905466] dump_stack+0x1b9/0x294 [ 615.909078] ? dump_stack_print_info.cold.2+0x52/0x52 [ 615.914259] nmi_cpu_backtrace.cold.4+0x19/0xce [ 615.918948] ? lapic_can_unplug_cpu.cold.26+0x3f/0x3f [ 615.924132] nmi_trigger_cpumask_backtrace+0x151/0x192 [ 615.929395] arch_trigger_cpumask_backtrace+0x14/0x20 [ 615.934563] watchdog+0xc10/0xf60 [ 615.938004] ? reset_hung_task_detector+0xb0/0xb0 [ 615.942828] ? __schedule+0x1e30/0x1e30 [ 615.946792] ? do_raw_spin_unlock+0x9e/0x2e0 [ 615.951189] ? do_raw_spin_trylock+0x1b0/0x1b0 [ 615.955762] ? __sanitizer_cov_trace_const_cmp8+0x18/0x20 [ 615.961336] ? __kthread_parkme+0x111/0x1d0 [ 615.965641] ? parse_args.cold.15+0x1b3/0x1b3 [ 615.970132] ? trace_hardirqs_on_caller+0x421/0x5c0 [ 615.975135] ? trace_hardirqs_on+0xd/0x10 [ 615.979270] kthread+0x345/0x410 [ 615.982624] ? reset_hung_task_detector+0xb0/0xb0 [ 615.987445] ? kthread_bind+0x40/0x40 [ 615.991239] ret_from_fork+0x3a/0x50 [ 615.995042] Sending NMI from CPU 1 to CPUs 0: [ 615.999582] NMI backtrace for cpu 0 skipped: idling at native_safe_halt+0x6/0x10 [ 616.000572] Kernel panic - not syncing: hung_task: blocked tasks [ 616.013304] CPU: 1 PID: 892 Comm: khungtaskd Not tainted 4.17.0-rc6+ #64 [ 616.020128] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 616.029459] Call Trace: [ 616.032047] dump_stack+0x1b9/0x294 [ 616.035657] ? dump_stack_print_info.cold.2+0x52/0x52 [ 616.040880] ? printk_safe_log_store+0x260/0x260 [ 616.045667] panic+0x22f/0x4de [ 616.048849] ? add_taint.cold.5+0x16/0x16 [ 616.052984] ? __sanitizer_cov_trace_const_cmp4+0x16/0x20 [ 616.058502] ? nmi_trigger_cpumask_backtrace+0x13a/0x192 [ 616.063951] ? printk_safe_flush+0xd7/0x130 [ 616.068267] watchdog+0xc21/0xf60 [ 616.071708] ? reset_hung_task_detector+0xb0/0xb0 [ 616.076548] ? __schedule+0x1e30/0x1e30 [ 616.080510] ? do_raw_spin_unlock+0x9e/0x2e0 [ 616.084900] ? do_raw_spin_trylock+0x1b0/0x1b0 [ 616.089480] ? __sanitizer_cov_trace_const_cmp8+0x18/0x20 [ 616.095013] ? __kthread_parkme+0x111/0x1d0 [ 616.099332] ? parse_args.cold.15+0x1b3/0x1b3 [ 616.103816] ? trace_hardirqs_on_caller+0x421/0x5c0 [ 616.108811] ? trace_hardirqs_on+0xd/0x10 [ 616.113029] kthread+0x345/0x410 [ 616.116385] ? reset_hung_task_detector+0xb0/0xb0 [ 616.121232] ? kthread_bind+0x40/0x40 [ 616.125016] ret_from_fork+0x3a/0x50 [ 616.129766] Dumping ftrace buffer: [ 616.133408] (ftrace buffer empty) [ 616.137101] Kernel Offset: disabled [ 616.140711] Rebooting in 86400 seconds..