[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 19.841081] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 22.982176] random: sshd: uninitialized urandom read (32 bytes read) [ 23.319195] random: sshd: uninitialized urandom read (32 bytes read) [ 24.067749] random: sshd: uninitialized urandom read (32 bytes read) [ 463.455322] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.35' (ECDSA) to the list of known hosts. [ 468.984229] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program executing program [ 615.392150] INFO: task syz-executor325:4508 blocked for more than 120 seconds. [ 615.399725] Not tainted 4.17.0-rc6+ #64 [ 615.404257] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [ 615.412229] syz-executor325 D23216 4508 4506 0x00000000 [ 615.417966] Call Trace: [ 615.420679] __schedule+0x801/0x1e30 [ 615.424418] ? __sched_text_start+0x8/0x8 [ 615.428643] ? do_raw_spin_trylock+0x1b0/0x1b0 [ 615.433359] ? _raw_spin_unlock_irqrestore+0x74/0xc0 [ 615.438476] ? trace_hardirqs_on_caller+0x421/0x5c0 [ 615.443505] ? trace_hardirqs_on+0xd/0x10 [ 615.447668] ? prepare_to_wait_event+0x38e/0xc50 [ 615.452435] ? prepare_to_wait_exclusive+0x540/0x540 [ 615.457543] ? find_held_lock+0x36/0x1c0 [ 615.461622] schedule+0xef/0x430 [ 615.464996] ? __schedule+0x1e30/0x1e30 [ 615.469043] ? check_same_owner+0x320/0x320 [ 615.473388] ? replenish_dl_entity.cold.53+0x37/0x37 [ 615.478503] ? __might_sleep+0x95/0x190 [ 615.482536] blk_mq_freeze_queue_wait+0x1ce/0x460 [ 615.487398] ? blk_mq_poll+0x930/0x930 [ 615.491299] ? blk_mq_run_hw_queue+0x119/0x390 [ 615.495901] ? blk_mq_run_work_fn+0x70/0x70 [ 615.500235] ? finish_wait+0x420/0x420 [ 615.504145] blk_freeze_queue+0x4a/0x80 [ 615.508134] blk_mq_freeze_queue+0x15/0x20 [ 615.512444] lo_ioctl+0xa9a/0x2130 [ 615.516008] ? lo_rw_aio_complete+0x430/0x430 [ 615.520561] blkdev_ioctl+0x9b6/0x2020 [ 615.524472] ? blkpg_ioctl+0xc40/0xc40 [ 615.528385] ? lock_downgrade+0x8e0/0x8e0 [ 615.532618] ? kasan_check_read+0x11/0x20 [ 615.536804] ? rcu_is_watching+0x85/0x140 [ 615.540970] ? rcu_pm_notify+0xc0/0xc0 [ 615.544883] ? vfs_writev+0x255/0x330 [ 615.548720] ? rcu_read_lock_sched_held+0x108/0x120 [ 615.553746] ? kfree+0x1e9/0x260 [ 615.557125] ? vfs_writev+0xfc/0x330 [ 615.560871] ? do_raw_spin_unlock+0x9e/0x2e0 [ 615.565305] ? vfs_iter_write+0xb0/0xb0 [ 615.569322] block_ioctl+0xee/0x130 [ 615.572967] ? blkdev_fallocate+0x400/0x400 [ 615.577320] do_vfs_ioctl+0x1cf/0x16a0 [ 615.581251] ? ioctl_preallocate+0x2e0/0x2e0 [ 615.585688] ? fget_raw+0x20/0x20 [ 615.589158] ? quarantine_put+0xeb/0x190 [ 615.593228] ? do_pwritev+0x167/0x270 [ 615.597103] ? security_file_ioctl+0x94/0xc0 [ 615.601525] ksys_ioctl+0xa9/0xd0 [ 615.604991] __x64_sys_ioctl+0x73/0xb0 [ 615.608930] do_syscall_64+0x1b1/0x800 [ 615.612844] ? syscall_slow_exit_work+0x4f0/0x4f0 [ 615.617784] ? syscall_return_slowpath+0x5c0/0x5c0 [ 615.622736] ? syscall_return_slowpath+0x30f/0x5c0 [ 615.627676] ? entry_SYSCALL_64_after_hwframe+0x59/0xbe [ 615.633062] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 615.637917] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 615.643127] RIP: 0033:0x443dd9 [ 615.646335] RSP: 002b:00007ffe8c463b48 EFLAGS: 00000286 ORIG_RAX: 0000000000000010 [ 615.654073] RAX: ffffffffffffffda RBX: 6f6f6c2f7665642f RCX: 0000000000443dd9 [ 615.661364] RDX: 0000000000000007 RSI: 0000000000004c06 RDI: 0000000000000007 [ 615.668663] RBP: 00000000006ce018 R08: 00000000004002e0 R09: 00000000004002e0 [ 615.675952] R10: 00000000004002e0 R11: 0000000000000286 R12: 0000000000401a80 [ 615.683946] R13: 0000000000401b10 R14: 0000000000000000 R15: 0000000000000000 [ 615.691261] [ 615.691261] Showing all locks held in the system: [ 615.697617] 2 locks held by khungtaskd/893: [ 615.702005] #0: (ptrval) (rcu_read_lock){....}, at: watchdog+0x1ff/0xf60 [ 615.709750] #1: (ptrval) (tasklist_lock){.+.+}, at: debug_show_all_locks+0xde/0x34a [ 615.718426] 2 locks held by getty/4481: [ 615.722404] #0: (ptrval) (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 [ 615.730679] #1: (ptrval) (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 [ 615.739617] 2 locks held by getty/4482: [ 615.743618] #0: (ptrval) (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 [ 615.751888] #1: (ptrval) (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 [ 615.760778] 2 locks held by getty/4483: [ 615.764756] #0: (ptrval) (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 [ 615.773039] #1: (ptrval) (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 [ 615.781924] 2 locks held by getty/4484: [ 615.785917] #0: (ptrval) (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 [ 615.794184] #1: (ptrval) (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 [ 615.803081] 2 locks held by getty/4485: [ 615.807061] #0: (ptrval) (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 [ 615.815349] #1: (ptrval) (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 [ 615.824241] 2 locks held by getty/4486: [ 615.828236] #0: (ptrval) (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 [ 615.836504] #1: (ptrval) (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 [ 615.845400] 2 locks held by getty/4487: [ 615.849389] #0: (ptrval) (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 [ 615.857678] #1: (ptrval) (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 [ 615.866560] 1 lock held by syz-executor325/4508: [ 615.871344] #0: (ptrval) (&lo->lo_ctl_mutex/1){+.+.}, at: lo_ioctl+0x8d/0x2130 [ 615.879546] [ 615.881195] ============================================= [ 615.881195] [ 615.888239] NMI backtrace for cpu 1 [ 615.891901] CPU: 1 PID: 893 Comm: khungtaskd Not tainted 4.17.0-rc6+ #64 [ 615.898723] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 615.908064] Call Trace: [ 615.910701] dump_stack+0x1b9/0x294 [ 615.914326] ? dump_stack_print_info.cold.2+0x52/0x52 [ 615.919512] nmi_cpu_backtrace.cold.4+0x19/0xce [ 615.924219] ? lapic_can_unplug_cpu.cold.26+0x3f/0x3f [ 615.929393] nmi_trigger_cpumask_backtrace+0x151/0x192 [ 615.934653] arch_trigger_cpumask_backtrace+0x14/0x20 [ 615.939828] watchdog+0xc10/0xf60 [ 615.943265] ? reset_hung_task_detector+0xb0/0xb0 [ 615.948092] ? __schedule+0x1e30/0x1e30 [ 615.952048] ? do_raw_spin_unlock+0x9e/0x2e0 [ 615.956434] ? do_raw_spin_trylock+0x1b0/0x1b0 [ 615.960995] ? __sanitizer_cov_trace_const_cmp8+0x18/0x20 [ 615.966549] ? __kthread_parkme+0x111/0x1d0 [ 615.970851] ? parse_args.cold.15+0x1b3/0x1b3 [ 615.975323] ? trace_hardirqs_on_caller+0x421/0x5c0 [ 615.980316] ? trace_hardirqs_on+0xd/0x10 [ 615.984445] kthread+0x345/0x410 [ 615.987793] ? reset_hung_task_detector+0xb0/0xb0 [ 615.992613] ? kthread_bind+0x40/0x40 [ 615.996394] ret_from_fork+0x3a/0x50 [ 616.000175] Sending NMI from CPU 1 to CPUs 0: [ 616.004724] NMI backtrace for cpu 0 skipped: idling at native_safe_halt+0x6/0x10 [ 616.005696] Kernel panic - not syncing: hung_task: blocked tasks [ 616.018456] CPU: 1 PID: 893 Comm: khungtaskd Not tainted 4.17.0-rc6+ #64 [ 616.025275] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 616.034610] Call Trace: [ 616.037186] dump_stack+0x1b9/0x294 [ 616.040800] ? dump_stack_print_info.cold.2+0x52/0x52 [ 616.046029] ? printk_safe_log_store+0x260/0x260 [ 616.050801] panic+0x22f/0x4de [ 616.053975] ? add_taint.cold.5+0x16/0x16 [ 616.058106] ? __sanitizer_cov_trace_const_cmp4+0x16/0x20 [ 616.063624] ? nmi_trigger_cpumask_backtrace+0x13a/0x192 [ 616.069066] ? printk_safe_flush+0xd7/0x130 [ 616.073372] watchdog+0xc21/0xf60 [ 616.076811] ? reset_hung_task_detector+0xb0/0xb0 [ 616.081639] ? __schedule+0x1e30/0x1e30 [ 616.085595] ? do_raw_spin_unlock+0x9e/0x2e0 [ 616.089983] ? do_raw_spin_trylock+0x1b0/0x1b0 [ 616.094546] ? __sanitizer_cov_trace_const_cmp8+0x18/0x20 [ 616.100074] ? __kthread_parkme+0x111/0x1d0 [ 616.104374] ? parse_args.cold.15+0x1b3/0x1b3 [ 616.108848] ? trace_hardirqs_on_caller+0x421/0x5c0 [ 616.113843] ? trace_hardirqs_on+0xd/0x10 [ 616.117974] kthread+0x345/0x410 [ 616.121322] ? reset_hung_task_detector+0xb0/0xb0 [ 616.126143] ? kthread_bind+0x40/0x40 [ 616.129925] ret_from_fork+0x3a/0x50 [ 616.134203] Dumping ftrace buffer: [ 616.137814] (ftrace buffer empty) [ 616.141504] Kernel Offset: disabled [ 616.145115] Rebooting in 86400 seconds..