[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 19.328284] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 22.777195] random: sshd: uninitialized urandom read (32 bytes read) [ 23.016135] random: sshd: uninitialized urandom read (32 bytes read) [ 23.806982] random: sshd: uninitialized urandom read (32 bytes read) [ 145.400781] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.43' (ECDSA) to the list of known hosts. [ 150.954098] 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 [ 183.775061] BUG: workqueue lockup - pool cpus=0 node=0 flags=0x0 nice=0 stuck for 32s! [ 183.783579] BUG: workqueue lockup - pool cpus=1 node=0 flags=0x0 nice=0 stuck for 32s! [ 183.791678] BUG: workqueue lockup - pool cpus=0-1 flags=0x4 nice=0 stuck for 32s! [ 183.799348] Showing busy workqueues and worker pools: [ 183.804609] workqueue events: flags=0x0 [ 183.809809] pwq 2: cpus=1 node=0 flags=0x0 nice=0 active=2/256 [ 183.816154] pending: defense_work_handler, cache_reap [ 183.821753] pwq 0: cpus=0 node=0 flags=0x0 nice=0 active=2/256 [ 183.827913] pending: vmstat_shepherd, cache_reap [ 183.833057] workqueue events_unbound: flags=0x2 [ 183.837810] pwq 4: cpus=0-1 flags=0x4 nice=0 active=29/512 [ 183.846037] in-flight: 7:flush_to_ldisc flush_to_ldisc, 50:flush_to_ldisc flush_to_ldisc, 122:flush_to_ldisc flush_to_ldisc, 4557:flush_to_ldisc flush_to_ldisc, 4567:flush_to_ldisc flush_to_ldisc, 23:flush_to_ldisc flush_to_ldisc, 4569:flush_to_ldisc flush_to_ldisc, 4565:flush_to_ldisc flush_to_ldisc, 4560:flush_to_ldisc flush_to_ldisc, 4550:flush_to_ldisc flush_to_ldisc, 4551:flush_to_ldisc flush_to_ldisc, 4571:flush_to_ldisc, 4555:flush_to_ldisc flush_to_ldisc, 4561:flush_to_ldisc, 4553:flush_to_ldisc flush_to_ldisc [ 183.892672] pending: flush_to_ldisc [ 183.896657] [ 183.896663] ====================================================== [ 183.896668] WARNING: possible circular locking dependency detected [ 183.896671] 4.18.0-rc1+ #115 Not tainted [ 183.896676] ------------------------------------------------------ [ 183.896681] kworker/u4:15/4571 is trying to acquire lock: [ 183.896684] (____ptrval____) (console_owner){-.-.}, at: console_unlock+0x54e/0x10b0 [ 183.896698] [ 183.896702] but task is already holding lock: [ 183.896705] (____ptrval____) (&pool->lock/1){..-.}, at: show_workqueue_state.cold.48+0xb16/0x15ec [ 183.896721] [ 183.896725] which lock already depends on the new lock. [ 183.896727] [ 183.896730] [ 183.896734] the existing dependency chain (in reverse order) is: [ 183.896736] [ 183.896739] -> #3 (&pool->lock/1){..-.}: [ 183.896754] _raw_spin_lock+0x2a/0x40 [ 183.896757] __queue_work+0x352/0x1410 [ 183.896761] queue_work_on+0x19a/0x1e0 [ 183.896765] tty_schedule_flip+0x14c/0x1d0 [ 183.896769] tty_flip_buffer_push+0x15/0x20 [ 183.896772] pty_write+0x19d/0x1f0 [ 183.896776] n_tty_write+0xc5b/0x11a0 [ 183.896779] tty_write+0x45f/0xae0 [ 183.896783] __vfs_write+0x117/0x9f0 [ 183.896787] vfs_write+0x1f8/0x560 [ 183.896791] ksys_write+0x101/0x260 [ 183.896794] __x64_sys_write+0x73/0xb0 [ 183.896798] do_syscall_64+0x1b9/0x820 [ 183.896803] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 183.896805] [ 183.896807] -> #2 (&(&port->lock)->rlock){-.-.}: [ 183.896821] _raw_spin_lock_irqsave+0x96/0xc0 [ 183.896825] tty_port_tty_get+0x20/0x80 [ 183.896829] tty_port_default_wakeup+0x15/0x40 [ 183.896832] tty_port_tty_wakeup+0x5d/0x70 [ 183.896836] uart_write_wakeup+0x44/0x60 [ 183.896840] serial8250_tx_chars+0x4be/0xb60 [ 183.896845] serial8250_handle_irq.part.25+0x1ee/0x280 [ 183.896849] serial8250_default_handle_irq+0xc8/0x150 [ 183.896853] serial8250_interrupt+0xfa/0x1d0 [ 183.896857] __handle_irq_event_percpu+0x1c8/0xaf0 [ 183.896861] handle_irq_event_percpu+0xa0/0x1d0 [ 183.896865] handle_irq_event+0xa7/0x135 [ 183.896869] handle_edge_irq+0x20f/0x870 [ 183.896872] handle_irq+0x18c/0x2e7 [ 183.896876] do_IRQ+0x78/0x190 [ 183.896879] ret_from_intr+0x0/0x1e [ 183.896883] native_safe_halt+0x6/0x10 [ 183.896887] default_idle+0xc7/0x450 [ 183.896890] arch_cpu_idle+0x10/0x20 [ 183.896894] default_idle_call+0x6d/0x90 [ 183.896898] do_idle+0x3aa/0x570 [ 183.896901] cpu_startup_entry+0x10c/0x120 [ 183.896905] start_secondary+0x433/0x5d0 [ 183.896909] secondary_startup_64+0xa5/0xb0 [ 183.896911] [ 183.896913] -> #1 (&port_lock_key){-.-.}: [ 183.896927] _raw_spin_lock_irqsave+0x96/0xc0 [ 183.896931] serial8250_console_write+0x8d5/0xb00 [ 183.896935] univ8250_console_write+0x5f/0x70 [ 183.896939] console_unlock+0xab1/0x10b0 [ 183.896943] vprintk_emit+0x6c6/0xdf0 [ 183.896946] vprintk_default+0x28/0x30 [ 183.896950] vprintk_func+0x7a/0xe7 [ 183.896953] printk+0xa7/0xcf [ 183.896957] register_console+0x7e7/0xc00 [ 183.896961] univ8250_console_init+0x3f/0x4b [ 183.896965] console_init+0x6e1/0xa54 [ 183.896968] start_kernel+0x610/0x949 [ 183.896973] x86_64_start_reservations+0x29/0x2b [ 183.896977] x86_64_start_kernel+0x76/0x79 [ 183.896981] secondary_startup_64+0xa5/0xb0 [ 183.896983] [ 183.896985] -> #0 (console_owner){-.-.}: [ 183.896998] lock_acquire+0x1e4/0x540 [ 183.897002] console_unlock+0x5bb/0x10b0 [ 183.897005] vprintk_emit+0x6c6/0xdf0 [ 183.897009] vprintk_default+0x28/0x30 [ 183.897012] vprintk_func+0x7a/0xe7 [ 183.897016] printk+0xa7/0xcf [ 183.897020] show_workqueue_state.cold.48+0xcb8/0x15ec [ 183.897024] wq_watchdog_timer_fn+0x709/0x830 [ 183.897028] call_timer_fn+0x242/0x970 [ 183.897031] __run_timers+0x7a6/0xc70 [ 183.897035] run_timer_softirq+0x60/0x70 [ 183.897039] __do_softirq+0x2e8/0xb17 [ 183.897042] irq_exit+0x1d1/0x200 [ 183.897046] smp_apic_timer_interrupt+0x186/0x730 [ 183.897050] apic_timer_interrupt+0xf/0x20 [ 183.897054] __sanitizer_cov_trace_pc+0x14/0x50 [ 183.897058] __process_echoes+0x1fd/0x8d0 [ 183.897062] commit_echoes+0x163/0x1d0 [ 183.897066] n_tty_receive_buf_common+0x205b/0x2c60 [ 183.897070] n_tty_receive_buf2+0x33/0x40 [ 183.897074] tty_ldisc_receive_buf+0xb0/0x190 [ 183.897078] tty_port_default_receive_buf+0x115/0x180 [ 183.897082] flush_to_ldisc+0x3fd/0x570 [ 183.897086] process_one_work+0xc73/0x1ba0 [ 183.897090] worker_thread+0x189/0x13c0 [ 183.897093] kthread+0x345/0x410 [ 183.897096] ret_from_fork+0x3a/0x50 [ 183.897098] [ 183.897103] other info that might help us debug this: [ 183.897105] [ 183.897108] Chain exists of: [ 183.897109] console_owner --> &(&port->lock)->rlock --> &pool->lock/1 [ 183.897129] [ 183.897133] Possible unsafe locking scenario: [ 183.897135] [ 183.897139] CPU0 CPU1 [ 183.897142] ---- ---- [ 183.897145] lock(&pool->lock/1); [ 183.897160] lock(&(&port->lock)->rlock); [ 183.897169] lock(&pool->lock/1); [ 183.897179] lock(console_owner); [ 183.897186] [ 183.897189] *** DEADLOCK *** [ 183.897191] [ 183.897195] 10 locks held by kworker/u4:15/4571: [ 183.897197] #0: (____ptrval____) ((wq_completion)"events_unbound"){+.+.}, at: process_one_work+0xb44/0x1ba0 [ 183.897215] #1: (____ptrval____) ((work_completion)(&buf->work)){+.+.}, at: process_one_work+0xb9b/0x1ba0 [ 183.897232] #2: (____ptrval____) (&port->buf.lock/1){+.+.}, at: flush_to_ldisc+0xbf/0x570 [ 183.897250] #3: (____ptrval____) (&tty->ldisc_sem){++++}, at: tty_ldisc_ref+0x22/0x90 [ 183.897266] #4: (____ptrval____) (&o_tty->termios_rwsem/1){++++}, at: n_tty_receive_buf_common+0xeb/0x2c60 [ 183.897286] #5: (____ptrval____) (&ldata->output_lock){+.+.}, at: commit_echoes+0x13f/0x1d0 [ 183.897302] #6: (____ptrval____) ((&wq_watchdog_timer)){+.-.}, at: call_timer_fn+0x1cd/0x970 [ 183.897318] #7: (____ptrval____) (rcu_read_lock_sched){....}, at: show_workqueue_state+0x0/0x1d0 [ 183.897335] #8: (____ptrval____) (&pool->lock/1){..-.}, at: show_workqueue_state.cold.48+0xb16/0x15ec [ 183.897354] #9: (____ptrval____) (console_lock){+.+.}, at: vprintk_emit+0x6ad/0xdf0 [ 183.897371] [ 183.897374] stack backtrace: [ 183.897379] CPU: 0 PID: 4571 Comm: kworker/u4:15 Not tainted 4.18.0-rc1+ #115 [ 183.897386] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 183.897390] Workqueue: events_unbound flush_to_ldisc [ 183.897395] Call Trace: [ 183.897398] [ 183.897401] dump_stack+0x1c9/0x2b4 [ 183.897406] ? dump_stack_print_info.cold.2+0x52/0x52 [ 183.897409] ? vprintk_func+0xd0/0xe7 [ 183.897414] print_circular_bug.isra.36.cold.56+0x1bd/0x27d [ 183.897417] ? save_trace+0xe0/0x290 [ 183.897421] __lock_acquire+0x3449/0x5020 [ 183.897425] ? debug_check_no_locks_freed+0x310/0x310 [ 183.897429] ? put_dec+0x3b/0xf0 [ 183.897433] ? __sanitizer_cov_trace_const_cmp4+0x16/0x20 [ 183.897438] ? __sanitizer_cov_trace_const_cmp1+0x1a/0x20 [ 183.897442] ? format_decode+0x1b1/0xaf0 [ 183.897446] ? graph_lock+0x170/0x170 [ 183.897449] ? graph_lock+0x170/0x170 [ 183.897454] ? __sanitizer_cov_trace_const_cmp8+0x18/0x20 [ 183.897457] ? find_held_lock+0x36/0x1c0 [ 183.897461] lock_acquire+0x1e4/0x540 [ 183.897465] ? console_unlock+0x54e/0x10b0 [ 183.897469] ? lock_release+0xa30/0xa30 [ 183.897473] ? kasan_check_read+0x11/0x20 [ 183.897477] ? do_raw_spin_unlock+0xa7/0x2f0 [ 183.897481] ? do_raw_spin_trylock+0x1c0/0x1c0 [ 183.897485] ? kasan_check_write+0x14/0x20 [ 183.897489] ? do_raw_spin_lock+0xc1/0x200 [ 183.897493] console_unlock+0x5bb/0x10b0 [ 183.897497] ? console_unlock+0x54e/0x10b0 [ 183.897501] ? kmsg_dump_get_buffer+0xae0/0xae0 [ 183.897505] ? kasan_check_write+0x14/0x20 [ 183.897509] ? do_raw_spin_lock+0xc1/0x200 [ 183.897512] ? trace_hardirqs_off+0xd/0x10 [ 183.897517] ? _raw_spin_unlock_irqrestore+0x63/0xc0 [ 183.897520] ? vprintk_emit+0x6ad/0xdf0 [ 183.897525] ? __down_trylock_console_sem+0x155/0x200 [ 183.897528] vprintk_emit+0x6c6/0xdf0 [ 183.897532] ? wake_up_klogd+0x110/0x110 [ 183.897537] ? smp_call_function_single_interrupt+0x660/0x660 [ 183.897540] ? mark_held_locks+0xc9/0x160 [ 183.897544] vprintk_default+0x28/0x30 [ 183.897548] vprintk_func+0x7a/0xe7 [ 183.897551] printk+0xa7/0xcf [ 183.897555] ? kmsg_dump_rewind_nolock+0xe4/0xe4 [ 183.897559] ? kasan_check_write+0x14/0x20 [ 183.897563] ? pr_cont_pool_info+0x2/0x13f [ 183.897567] show_workqueue_state.cold.48+0xcb8/0x15ec [ 183.897571] ? print_worker_info+0x540/0x540 [ 183.897574] ? idr_preload+0x40/0x40 [ 183.897579] ? __down_trylock_console_sem+0x155/0x200 [ 183.897583] ? vprintk_emit+0x3f2/0xdf0 [ 183.897586] ? graph_lock+0x170/0x170 [ 183.897590] ? wake_up_klogd+0x110/0x110 [ 183.897594] ? find_held_lock+0x36/0x1c0 [ 183.897597] ? lock_downgrade+0x8f0/0x8f0 [ 183.897601] ? idr_find+0x50/0x50 [ 183.897605] ? rcu_is_watching+0x8c/0x150 [ 183.897609] ? __lock_is_held+0xb5/0x140 [ 183.897613] ? rcu_report_qs_rnp+0x7a0/0x7a0 [ 183.897617] wq_watchdog_timer_fn+0x709/0x830 [ 183.897621] ? show_workqueue_state+0x1d0/0x1d0 [ 183.897626] ? __sanitizer_cov_trace_const_cmp4+0x16/0x20 [ 183.897630] ? run_posix_cpu_timers+0x6c7/0x2580 [ 183.897634] ? graph_lock+0x170/0x170 [ 183.897637] ? lock_acquire+0x1e4/0x540 [ 183.897641] ? call_timer_fn+0x1cd/0x970 [ 183.897645] ? __lock_is_held+0xb5/0x140 [ 183.897649] ? __lock_is_held+0xb5/0x140 [ 183.897653] call_timer_fn+0x242/0x970 [ 183.897656] ? show_workqueue_state+0x1d0/0x1d0 [ 183.897660] ? process_timeout+0x40/0x40 [ 183.897663] ? lock_downgrade+0x8f0/0x8f0 [ 183.897667] ? trace_hardirqs_off+0xd/0x10 [ 183.897672] ? _raw_spin_unlock_irqrestore+0x63/0xc0 [ 183.897675] ? mark_held_locks+0xc9/0x160 [ 183.897679] ? do_raw_spin_trylock+0x1c0/0x1c0 [ 183.897683] ? _raw_spin_unlock_irq+0x27/0x70 [ 183.897688] ? trace_hardirqs_on_caller+0x19e/0x5c0 [ 183.897692] ? show_workqueue_state+0x1d0/0x1d0 [ 183.897696] __run_timers+0x7a6/0xc70 [ 183.897701] ? __bpf_trace_timer_expire_entry+0x30/0x30 [ 183.897705] ? __sanitizer_cov_trace_cmp8+0x18/0x20 [ 183.897708] ? graph_lock+0x170/0x170 [ 183.897712] ? enqueue_hrtimer+0x18e/0x540 [ 183.897717] ? hrtimer_update_softirq_timer+0xa0/0xa0 [ 183.897721] ? find_held_lock+0x36/0x1c0 [ 183.897724] ? graph_lock+0x170/0x170 [ 183.897728] ? lock_downgrade+0x8f0/0x8f0 [ 183.897732] ? __lock_is_held+0xb5/0x [ 183.897738] Lost 150 message(s)! [ 184.915994] workqueue events_power_efficient: flags=0x80 [ 184.921454] pwq 2: cpus=1 node=0 flags=0x0 nice=0 active=3/256 [ 184.927605] pending: gc_worker, neigh_periodic_work, do_cache_clean [ 184.934386] pwq 0: cpus=0 node=0 flags=0x0 nice=0 active=1/256 [ 184.940535] pending: neigh_periodic_work [ 184.944956] workqueue mm_percpu_wq: flags=0x8 [ 184.949533] pwq 2: cpus=1 node=0 flags=0x0 nice=0 active=1/256 [ 184.955679] pending: vmstat_update [ 184.959577] pwq 0: cpus=0 node=0 flags=0x0 nice=0 active=1/256 [ 184.965738] pending: vmstat_update [ 184.969646] workqueue writeback: flags=0x4e [ 184.973961] pwq 4: cpus=0-1 flags=0x4 nice=0 active=1/256 [ 184.979674] pending: wb_workfn [ 184.983225] workqueue kblockd: flags=0x18 [ 184.987368] pwq 3: cpus=1 node=0 flags=0x0 nice=-20 active=1/256 [ 184.993689] pending: blk_mq_timeout_work [ 184.998131] workqueue dm_bufio_cache: flags=0x8 [ 185.002793] pwq 0: cpus=0 node=0 flags=0x0 nice=0 active=1/256 [ 185.008941] pending: work_fn [ 185.012330] pool 4: cpus=0-1 flags=0x4 nice=0 hung=33s workers=17 idle: 4574 4564