[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 19.956635] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 21.483538] random: sshd: uninitialized urandom read (32 bytes read) [ 21.915072] random: sshd: uninitialized urandom read (32 bytes read) [ 22.656758] random: sshd: uninitialized urandom read (32 bytes read) [ 434.072915] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.18' (ECDSA) to the list of known hosts. [ 439.619727] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program executing program [ 615.392202] INFO: task syz-executor193:4842 blocked for more than 120 seconds. [ 615.399882] Not tainted 4.17.0-rc3+ #26 [ 615.404465] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [ 615.412508] syz-executor193 D22544 4842 4840 0x00000000 [ 615.418272] Call Trace: [ 615.420995] __schedule+0x801/0x1e30 [ 615.424780] ? __sched_text_start+0x8/0x8 [ 615.429050] ? mark_held_locks+0xc9/0x160 [ 615.433347] ? do_raw_spin_trylock+0x1b0/0x1b0 [ 615.438095] ? _raw_spin_unlock_irqrestore+0x74/0xc0 [ 615.443269] ? trace_hardirqs_on_caller+0x421/0x5c0 [ 615.448347] ? trace_hardirqs_on+0xd/0x10 [ 615.452602] ? prepare_to_wait_event+0x37d/0xb90 [ 615.457426] ? prepare_to_wait_exclusive+0x530/0x530 [ 615.462584] ? find_held_lock+0x36/0x1c0 [ 615.466707] schedule+0xef/0x430 [ 615.470135] ? __schedule+0x1e30/0x1e30 [ 615.474235] ? check_same_owner+0x320/0x320 [ 615.478624] ? replenish_dl_entity.cold.52+0x37/0x37 [ 615.483780] ? __might_sleep+0x95/0x190 [ 615.487870] blk_mq_freeze_queue_wait+0x1ce/0x460 [ 615.492790] ? blk_mq_poll+0x930/0x930 [ 615.496736] ? blk_mq_run_hw_queue+0x119/0x390 [ 615.501367] ? blk_mq_run_work_fn+0x70/0x70 [ 615.505750] ? prepare_to_wait+0x4d0/0x4d0 [ 615.510101] blk_freeze_queue+0x4a/0x80 [ 615.514163] blk_mq_freeze_queue+0x15/0x20 [ 615.518621] lo_ioctl+0xa9a/0x2130 [ 615.522256] ? lo_rw_aio_complete+0x430/0x430 [ 615.526819] blkdev_ioctl+0x9b6/0x2020 [ 615.530760] ? blkpg_ioctl+0xc40/0xc40 [ 615.534699] ? lock_downgrade+0x8e0/0x8e0 [ 615.538996] ? kasan_check_read+0x11/0x20 [ 615.543255] ? rcu_is_watching+0x85/0x140 [ 615.547460] ? rcu_pm_notify+0xc0/0xc0 [ 615.551474] ? vfs_writev+0x255/0x330 [ 615.555352] ? rcu_read_lock_sched_held+0x108/0x120 [ 615.560473] ? kfree+0x1e9/0x260 [ 615.563911] ? vfs_writev+0xfc/0x330 [ 615.567690] ? do_raw_spin_unlock+0x9e/0x2e0 [ 615.572177] ? vfs_iter_write+0xb0/0xb0 [ 615.576296] block_ioctl+0xee/0x130 [ 615.579989] ? blkdev_fallocate+0x400/0x400 [ 615.584431] do_vfs_ioctl+0x1cf/0x16a0 [ 615.588364] ? ioctl_preallocate+0x2e0/0x2e0 [ 615.592887] ? fget_raw+0x20/0x20 [ 615.596434] ? quarantine_put+0xeb/0x190 [ 615.600552] ? do_pwritev+0x167/0x270 [ 615.604461] ? security_file_ioctl+0x94/0xc0 [ 615.608959] ksys_ioctl+0xa9/0xd0 [ 615.612476] __x64_sys_ioctl+0x73/0xb0 [ 615.616496] do_syscall_64+0x1b1/0x800 [ 615.620447] ? syscall_return_slowpath+0x5c0/0x5c0 [ 615.625444] ? syscall_return_slowpath+0x30f/0x5c0 [ 615.630441] ? entry_SYSCALL_64_after_hwframe+0x59/0xbe [ 615.635873] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 615.640775] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 615.646029] RIP: 0033:0x443df9 [ 615.649258] RSP: 002b:00007ffed3ff0378 EFLAGS: 00000286 ORIG_RAX: 0000000000000010 [ 615.657050] RAX: ffffffffffffffda RBX: 6f6f6c2f7665642f RCX: 0000000000443df9 [ 615.664366] RDX: 0000000000000007 RSI: 0000000000004c06 RDI: 0000000000000007 [ 615.671680] RBP: 00000000006ce018 R08: 00000000004002e0 R09: 00000000004002e0 [ 615.679006] R10: 00000000004002e0 R11: 0000000000000286 R12: 0000000000401aa0 [ 615.686363] R13: 0000000000401b30 R14: 0000000000000000 R15: 0000000000000000 [ 615.693686] [ 615.693686] Showing all locks held in the system: [ 615.700077] 2 locks held by khungtaskd/892: [ 615.704547] #0: (ptrval) (rcu_read_lock){....}, at: watchdog+0x1ff/0xf60 [ 615.712347] #1: (ptrval) (tasklist_lock){.+.+}, at: debug_show_all_locks+0xde/0x34a [ 615.721092] 2 locks held by getty/4484: [ 615.725108] #0: (ptrval) (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 [ 615.733438] #1: (ptrval) (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 [ 615.742459] 2 locks held by getty/4485: [ 615.746458] #0: (ptrval) (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 [ 615.754758] #1: (ptrval) (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 [ 615.763662] 2 locks held by getty/4486: [ 615.767682] #0: (ptrval) (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 [ 615.776022] #1: (ptrval) (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 [ 615.784934] 2 locks held by getty/4487: [ 615.788974] #0: (ptrval) (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 [ 615.797305] #1: (ptrval) (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 [ 615.806224] 2 locks held by getty/4488: [ 615.810231] #0: (ptrval) (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 [ 615.818558] #1: (ptrval) (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 [ 615.827481] 2 locks held by getty/4489: [ 615.831566] #0: (ptrval) (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 [ 615.839874] #1: (ptrval) (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 [ 615.848781] 2 locks held by getty/4490: [ 615.852795] #0: (ptrval) (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 [ 615.861109] #1: (ptrval) (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 [ 615.870051] 1 lock held by syz-executor193/4842: [ 615.874832] #0: (ptrval) (&lo->lo_ctl_mutex/1){+.+.}, at: lo_ioctl+0x8d/0x2130 [ 615.883059] [ 615.884712] ============================================= [ 615.884712] [ 615.891784] NMI backtrace for cpu 1 [ 615.895459] CPU: 1 PID: 892 Comm: khungtaskd Not tainted 4.17.0-rc3+ #26 [ 615.902288] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 615.911642] Call Trace: [ 615.914323] dump_stack+0x1b9/0x294 [ 615.917944] ? dump_stack_print_info.cold.2+0x52/0x52 [ 615.923120] nmi_cpu_backtrace.cold.4+0x19/0xce [ 615.927811] ? lapic_can_unplug_cpu.cold.26+0x3f/0x3f [ 615.934989] nmi_trigger_cpumask_backtrace+0x151/0x192 [ 615.940258] arch_trigger_cpumask_backtrace+0x14/0x20 [ 615.945433] watchdog+0xc10/0xf60 [ 615.948889] ? reset_hung_task_detector+0xb0/0xb0 [ 615.953725] ? __schedule+0x1e30/0x1e30 [ 615.957686] ? do_raw_spin_unlock+0x9e/0x2e0 [ 615.962077] ? do_raw_spin_trylock+0x1b0/0x1b0 [ 615.966659] ? _raw_spin_unlock_irqrestore+0x74/0xc0 [ 615.971753] ? trace_hardirqs_on_caller+0x421/0x5c0 [ 615.976755] ? __sanitizer_cov_trace_const_cmp8+0x18/0x20 [ 615.982360] ? __kthread_parkme+0x1b7/0x280 [ 615.986686] kthread+0x345/0x410 [ 615.990041] ? reset_hung_task_detector+0xb0/0xb0 [ 615.994867] ? kthread_bind+0x40/0x40 [ 615.998654] ret_from_fork+0x3a/0x50 [ 616.002464] Sending NMI from CPU 1 to CPUs 0: [ 616.007030] NMI backtrace for cpu 0 skipped: idling at native_safe_halt+0x6/0x10 [ 616.008053] Kernel panic - not syncing: hung_task: blocked tasks [ 616.020835] CPU: 1 PID: 892 Comm: khungtaskd Not tainted 4.17.0-rc3+ #26 [ 616.027657] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 616.036994] Call Trace: [ 616.039584] dump_stack+0x1b9/0x294 [ 616.043213] ? dump_stack_print_info.cold.2+0x52/0x52 [ 616.048396] ? printk_safe_log_store+0x260/0x260 [ 616.053190] panic+0x22f/0x4de [ 616.056375] ? add_taint.cold.5+0x16/0x16 [ 616.060512] ? __sanitizer_cov_trace_const_cmp4+0x16/0x20 [ 616.066039] ? nmi_trigger_cpumask_backtrace+0x13a/0x192 [ 616.071473] ? printk_safe_flush+0xd7/0x130 [ 616.075781] watchdog+0xc21/0xf60 [ 616.079222] ? reset_hung_task_detector+0xb0/0xb0 [ 616.084055] ? __schedule+0x1e30/0x1e30 [ 616.088018] ? do_raw_spin_unlock+0x9e/0x2e0 [ 616.092411] ? do_raw_spin_trylock+0x1b0/0x1b0 [ 616.096983] ? _raw_spin_unlock_irqrestore+0x74/0xc0 [ 616.102076] ? trace_hardirqs_on_caller+0x421/0x5c0 [ 616.107080] ? __sanitizer_cov_trace_const_cmp8+0x18/0x20 [ 616.112606] ? __kthread_parkme+0x1b7/0x280 [ 616.116914] kthread+0x345/0x410 [ 616.120281] ? reset_hung_task_detector+0xb0/0xb0 [ 616.125110] ? kthread_bind+0x40/0x40 [ 616.128922] ret_from_fork+0x3a/0x50 [ 616.133238] Dumping ftrace buffer: [ 616.136907] (ftrace buffer empty) [ 616.140603] Kernel Offset: disabled [ 616.144232] Rebooting in 86400 seconds..