[ 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 Update UTMP about System Runlevel Changes. Debian GNU/Linux 9 syzkaller ttyS0 Warning: Permanently added '10.128.0.115' (ECDSA) to the list of known hosts. executing program syzkaller login: [ 44.993349][ T6830] [ 44.995732][ T6830] ============================================ [ 45.001872][ T6830] WARNING: possible recursive locking detected [ 45.008015][ T6830] 5.8.0-syzkaller #0 Not tainted [ 45.012939][ T6830] -------------------------------------------- [ 45.019087][ T6830] syz-executor639/6830 is trying to acquire lock: [ 45.025573][ T6830] ffff8880a6bc5530 (&tty->write_wait){-.-.}-{2:2}, at: io_poll_double_wake+0x108/0x360 [ 45.035183][ T6830] [ 45.035183][ T6830] but task is already holding lock: [ 45.042517][ T6830] ffff8880a6bc5530 (&tty->write_wait){-.-.}-{2:2}, at: __wake_up+0xb8/0x150 [ 45.051201][ T6830] [ 45.051201][ T6830] other info that might help us debug this: [ 45.059418][ T6830] Possible unsafe locking scenario: [ 45.059418][ T6830] [ 45.066849][ T6830] CPU0 [ 45.070110][ T6830] ---- [ 45.073359][ T6830] lock(&tty->write_wait); [ 45.079490][ T6830] lock(&tty->write_wait); [ 45.083970][ T6830] [ 45.083970][ T6830] *** DEADLOCK *** [ 45.083970][ T6830] [ 45.092083][ T6830] May be due to missing lock nesting notation [ 45.092083][ T6830] [ 45.100395][ T6830] 4 locks held by syz-executor639/6830: [ 45.105923][ T6830] #0: ffff8880a6bc5098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x21/0x70 [ 45.115619][ T6830] #1: ffff8880a6bc52e8 (&tty->termios_rwsem){++++}-{3:3}, at: tty_set_termios+0xc5/0x1510 [ 45.125765][ T6830] #2: ffff8880a6bc5098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref+0x18/0x80 [ 45.135026][ T6830] #3: ffff8880a6bc5530 (&tty->write_wait){-.-.}-{2:2}, at: __wake_up+0xb8/0x150 [ 45.144128][ T6830] [ 45.144128][ T6830] stack backtrace: [ 45.150008][ T6830] CPU: 0 PID: 6830 Comm: syz-executor639 Not tainted 5.8.0-syzkaller #0 [ 45.158328][ T6830] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 45.168363][ T6830] Call Trace: [ 45.171652][ T6830] dump_stack+0x1f0/0x31e [ 45.175974][ T6830] validate_chain+0x69a4/0x88a0 [ 45.180810][ T6830] ? validate_chain+0x94/0x88a0 [ 45.185810][ T6830] ? mark_lock+0x102/0x1b00 [ 45.190295][ T6830] ? check_noncircular+0x161/0x3a0 [ 45.195422][ T6830] ? mark_lock+0x102/0x1b00 [ 45.199926][ T6830] __lock_acquire+0x1161/0x2ab0 [ 45.204752][ T6830] ? __lock_acquire+0x1161/0x2ab0 [ 45.209759][ T6830] lock_acquire+0x160/0x730 [ 45.214237][ T6830] ? io_poll_double_wake+0x108/0x360 [ 45.219513][ T6830] _raw_spin_lock+0x2a/0x40 [ 45.223994][ T6830] ? io_poll_double_wake+0x108/0x360 [ 45.230205][ T6830] io_poll_double_wake+0x108/0x360 [ 45.235300][ T6830] ? lock_is_held_type+0xb3/0xe0 [ 45.240216][ T6830] __wake_up_common+0x30a/0x4e0 [ 45.245036][ T6830] __wake_up+0xd4/0x150 [ 45.249160][ T6830] n_tty_set_termios+0xa60/0x1080 [ 45.254153][ T6830] ? n_tty_ioctl+0x310/0x310 [ 45.258797][ T6830] tty_set_termios+0xcac/0x1510 [ 45.263615][ T6830] set_termios+0x4a1/0x580 [ 45.267999][ T6830] tty_mode_ioctl+0x7b2/0xa80 [ 45.272665][ T6830] ? n_tty_write+0x1170/0x1170 [ 45.277405][ T6830] tty_ioctl+0xf81/0x15c0 [ 45.281735][ T6830] ? do_vfs_ioctl+0x6bc/0x16d0 [ 45.286481][ T6830] ? bpf_lsm_file_ioctl+0x5/0x10 [ 45.291409][ T6830] ? tty_do_resize+0x180/0x180 [ 45.296152][ T6830] __se_sys_ioctl+0xfb/0x170 [ 45.300715][ T6830] do_syscall_64+0x31/0x70 [ 45.305118][ T6830] entry_SYSCALL_64_after_hwframe+0x44/0xa9 [ 45.310992][ T6830] RIP: 0033:0x4405b9 [ 45.314860][ T6830] Code: 18 89 d0 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 db 13 fc ff c3 66 2e 0f 1f 84 00 00 00 00 [ 45.334449][ T6830] RSP: 002b:00007ffdae6bfd28 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 [ 45.342827][ T6830] RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 00000000004405b9 [ 45.350768][ T6830] RDX: 0000000020000000 RSI: 0000000000005404 RDI: 0000000000000003 [ 45.358709][ T6830] RBP: 00000000006ca018 R08: 0000000000000000 R09: 0000000000000000 [ 45.366660][ T6830] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000401e20 [ 45.374619][ T6830] R13: 0000000000401eb0 R14: 0000000000000000 R15: 0000000000000000