[ OK ] Started Permit User Sessions. [ OK ] Started System Logging Service. [ OK ] Started OpenBSD Secure Shell server. [ OK ] Started getty on tty2-tty6 if dbus and logind are not available. [ OK ] Started Getty on tty6. [ OK ] Started Getty on tty5. [ OK ] Started Getty on tty4. [ OK ] Started Getty on tty3. [ OK ] Started Getty on tty2. Starting Load/Save RF Kill Switch Status... [ OK ] Started Getty on tty1. [ OK ] Started Serial Getty on ttyS0. [ OK ] Reached target Login Prompts. [ OK ] Reached target Multi-User System. [ OK ] Reached target Graphical Interface. Starting Update UTMP about System Runlevel Changes... [ OK ] Started Load/Save RF Kill Switch Status. [ OK ] Started Update UTMP about System Runlevel Changes. Debian GNU/Linux 9 syzkaller ttyS0 Warning: Permanently added '10.128.10.56' (ECDSA) to the list of known hosts. executing program syzkaller login: [ 60.016335][ T6831] [ 60.018670][ T6831] ============================================ [ 60.024786][ T6831] WARNING: possible recursive locking detected [ 60.030904][ T6831] 5.8.0-syzkaller #0 Not tainted [ 60.035803][ T6831] -------------------------------------------- [ 60.041918][ T6831] syz-executor960/6831 is trying to acquire lock: [ 60.048297][ T6831] ffff8880a66b54d8 (&ctx->completion_lock){....}-{2:2}, at: io_queue_linked_timeout+0x4c/0x200 [ 60.058596][ T6831] [ 60.058596][ T6831] but task is already holding lock: [ 60.065924][ T6831] ffff8880a66b54d8 (&ctx->completion_lock){....}-{2:2}, at: io_cqring_overflow_flush+0x814/0xaa0 [ 60.076390][ T6831] [ 60.076390][ T6831] other info that might help us debug this: [ 60.084415][ T6831] Possible unsafe locking scenario: [ 60.084415][ T6831] [ 60.091829][ T6831] CPU0 [ 60.095078][ T6831] ---- [ 60.098336][ T6831] lock(&ctx->completion_lock); [ 60.103235][ T6831] lock(&ctx->completion_lock); [ 60.108136][ T6831] [ 60.108136][ T6831] *** DEADLOCK *** [ 60.108136][ T6831] [ 60.116249][ T6831] May be due to missing lock nesting notation [ 60.116249][ T6831] [ 60.124661][ T6831] 1 lock held by syz-executor960/6831: [ 60.130116][ T6831] #0: ffff8880a66b54d8 (&ctx->completion_lock){....}-{2:2}, at: io_cqring_overflow_flush+0x814/0xaa0 [ 60.141020][ T6831] [ 60.141020][ T6831] stack backtrace: [ 60.146881][ T6831] CPU: 0 PID: 6831 Comm: syz-executor960 Not tainted 5.8.0-syzkaller #0 [ 60.155167][ T6831] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 60.165190][ T6831] Call Trace: [ 60.168447][ T6831] dump_stack+0x18f/0x20d [ 60.172745][ T6831] __lock_acquire.cold+0x115/0x396 [ 60.177827][ T6831] ? lockdep_hardirqs_on_prepare+0x530/0x530 [ 60.183774][ T6831] lock_acquire+0x1f1/0xad0 [ 60.188247][ T6831] ? io_queue_linked_timeout+0x4c/0x200 [ 60.193759][ T6831] ? lock_release+0x8e0/0x8e0 [ 60.198403][ T6831] ? lock_downgrade+0x830/0x830 [ 60.203222][ T6831] ? find_held_lock+0x2d/0x110 [ 60.207972][ T6831] ? lockdep_hardirqs_off+0x89/0xc0 [ 60.213138][ T6831] _raw_spin_lock_irq+0x5b/0x80 [ 60.217959][ T6831] ? io_queue_linked_timeout+0x4c/0x200 [ 60.223471][ T6831] io_queue_linked_timeout+0x4c/0x200 [ 60.228811][ T6831] __io_queue_async_work+0x1f8/0x4c0 [ 60.234063][ T6831] io_commit_cqring+0x456/0x7a0 [ 60.238883][ T6831] io_cqring_overflow_flush+0x5b8/0xaa0 [ 60.244397][ T6831] ? io_timeout_fn+0x3f0/0x3f0 [ 60.249129][ T6831] ? lockdep_hardirqs_on_prepare+0x354/0x530 [ 60.255076][ T6831] ? trace_hardirqs_on+0x5f/0x220 [ 60.260072][ T6831] io_ring_ctx_wait_and_kill+0x30e/0x600 [ 60.265671][ T6831] io_uring_release+0x3e/0x50 [ 60.270314][ T6831] __fput+0x285/0x920 [ 60.274269][ T6831] ? io_ring_ctx_wait_and_kill+0x600/0x600 [ 60.280043][ T6831] task_work_run+0xdd/0x190 [ 60.284513][ T6831] do_exit+0xb7d/0x29f0 [ 60.288637][ T6831] ? mm_update_next_owner+0x7a0/0x7a0 [ 60.293975][ T6831] ? io_submit_sqes+0x2380/0x2380 [ 60.298964][ T6831] ? fput_many+0x2f/0x1a0 [ 60.303262][ T6831] ? lock_is_held_type+0xbb/0xf0 [ 60.308167][ T6831] do_group_exit+0x125/0x310 [ 60.312724][ T6831] __x64_sys_exit_group+0x3a/0x50 [ 60.317712][ T6831] do_syscall_64+0x2d/0x70 [ 60.322099][ T6831] entry_SYSCALL_64_after_hwframe+0x44/0xa9 [ 60.327958][ T6831] RIP: 0033:0x43f598 [ 60.331814][ T6831] Code: Bad RIP value. [ 60.335848][ T6831] RSP: 002b:00007ffd0cbd6088 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 [ 60.344226][ T6831] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000043f598 [ 60.352166][ T6831] RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000 [ 60.360103][ T6831] RBP: 00000000004beda8 R08: 00000000000000e7 R09: ffffffffffffffd0 [ 60.368056][ T6831] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001 [ 60.375993][ T6831] R13: 00000000006d11a0 R14: 0000000000000000 R15: 0000000000000000