[ OK ] Reached target Multi-User System. [ OK ] Reached target Graphical Interface. Starting Update UTMP about System Runlevel Changes... Starting Load/Save RF Kill Switch Status... [ OK ] Started Update UTMP about System Runlevel Changes. Debian GNU/Linux 9 syzkaller ttyS0 Warning: Permanently added '10.128.0.102' (ECDSA) to the list of known hosts. executing program syzkaller login: [ 45.511413][ T6826] [ 45.513757][ T6826] ============================================ [ 45.519913][ T6826] WARNING: possible recursive locking detected [ 45.526043][ T6826] 5.9.0-rc2-syzkaller #0 Not tainted [ 45.531304][ T6826] -------------------------------------------- [ 45.537447][ T6826] syz-executor492/6826 is trying to acquire lock: [ 45.543829][ T6826] ffff88809a42cc18 (&sighand->siglock){....}-{2:2}, at: __lock_task_sighand+0x158/0x260 [ 45.553536][ T6826] [ 45.553536][ T6826] but task is already holding lock: [ 45.560890][ T6826] ffff88809a42cc18 (&sighand->siglock){....}-{2:2}, at: force_sig_info_to_task+0x64/0x2e0 [ 45.570758][ T6826] [ 45.570758][ T6826] other info that might help us debug this: [ 45.578802][ T6826] Possible unsafe locking scenario: [ 45.578802][ T6826] [ 45.586226][ T6826] CPU0 [ 45.589479][ T6826] ---- [ 45.592730][ T6826] lock(&sighand->siglock); [ 45.597302][ T6826] lock(&sighand->siglock); [ 45.601864][ T6826] [ 45.601864][ T6826] *** DEADLOCK *** [ 45.601864][ T6826] [ 45.609983][ T6826] May be due to missing lock nesting notation [ 45.609983][ T6826] [ 45.618280][ T6826] 3 locks held by syz-executor492/6826: [ 45.623807][ T6826] #0: ffff88809a42cc18 (&sighand->siglock){....}-{2:2}, at: force_sig_info_to_task+0x64/0x2e0 [ 45.634122][ T6826] #1: ffff88809a42cc60 (&sighand->signalfd_wqh){....}-{2:2}, at: __wake_up+0xb8/0x150 [ 45.643736][ T6826] #2: ffffffff894fe510 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x5/0x30 [ 45.653019][ T6826] [ 45.653019][ T6826] stack backtrace: [ 45.659684][ T6826] CPU: 1 PID: 6826 Comm: syz-executor492 Not tainted 5.9.0-rc2-syzkaller #0 [ 45.668335][ T6826] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 45.678362][ T6826] Call Trace: [ 45.681636][ T6826] dump_stack+0x1f0/0x31e [ 45.685956][ T6826] validate_chain+0x69a4/0x88a0 [ 45.690782][ T6826] ? mark_lock+0x102/0x1b00 [ 45.695265][ T6826] ? validate_chain+0x16c3/0x88a0 [ 45.700269][ T6826] ? mark_lock+0x102/0x1b00 [ 45.704753][ T6826] __lock_acquire+0x1161/0x2ab0 [ 45.709591][ T6826] lock_acquire+0x160/0x730 [ 45.714112][ T6826] ? __lock_task_sighand+0x158/0x260 [ 45.719368][ T6826] _raw_spin_lock_irqsave+0x9e/0xc0 [ 45.724538][ T6826] ? __lock_task_sighand+0x158/0x260 [ 45.729792][ T6826] __lock_task_sighand+0x158/0x260 [ 45.734882][ T6826] task_work_add+0x13c/0x260 [ 45.739441][ T6826] __io_async_wake+0x2a2/0x3d0 [ 45.744183][ T6826] ? __io_async_wake+0x3d0/0x3d0 [ 45.749093][ T6826] __wake_up_common+0x30a/0x4e0 [ 45.753925][ T6826] __wake_up+0xd4/0x150 [ 45.758053][ T6826] __send_signal+0xae8/0xca0 [ 45.762625][ T6826] force_sig_info_to_task+0x24e/0x2e0 [ 45.767977][ T6826] force_sig_fault+0xbb/0x130 [ 45.772641][ T6826] __bad_area_nosemaphore+0x309/0x4b0 [ 45.778015][ T6826] exc_page_fault+0x124/0x1f0 [ 45.782689][ T6826] ? asm_exc_page_fault+0x8/0x30 [ 45.787607][ T6826] asm_exc_page_fault+0x1e/0x30 [ 45.792444][ T6826] RIP: 0033:0x400d4d [ 45.796318][ T6826] Code: 48 8b 54 24 e0 8b 86 0c 01 00 00 44 8b 86 08 01 00 00 c1 e0 04 8d b8 7f 01 00 00 83 e7 c0 45 85 c0 74 07 89 d0 31 d2 41 f7 f0 <4c> 8b 01 89 d0 c1 e0 06 4c 01 c8 4c 89 00 4c 8b 41 08 4c 89 40 08 [ 45.815923][ T6826] RSP: 002b:00007ffc16fa5808 EFLAGS: 00010246 [ 45.821967][ T6826] RAX: 0000000000000000 RBX: 0000000000000004 RCX: 0000000000000000 [ 45.829917][ T6826] RDX: 0000000000000005 RSI: 0000000020ee7000 RDI: 0000000000002140 [ 45.837964][ T6826] RBP: 00000000006ca018 R08: 0000000000000100 R09: 0000000000000000 [ 45.845926][ T6826] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000401d20 [ 45.853886][ T6826] R13: 0000000000401db0 R14: 0000000000000000 R15: 0000000000000000