[ 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 '10.128.0.183' (ECDSA) to the list of known hosts. executing program syzkaller login: [ 28.768124] ip_tables: iptables: counters copy to user failed while replacing table [ 28.777631] ip_tables: iptables: counters copy to user failed while replacing table [ 28.785989] ip_tables: iptables: counters copy to user failed while replacing table [ 28.794291] ip_tables: iptables: counters copy to user failed while replacing table [ 28.802653] ip_tables: iptables: counters copy to user failed while replacing table [ 28.811227] ip_tables: iptables: counters copy to user failed while replacing table [ 28.819708] ip_tables: iptables: counters copy to user failed while replacing table [ 28.828404] ip_tables: iptables: counters copy to user failed while replacing table [ 28.838570] ip_tables: iptables: counters copy to user failed while replacing table [ 28.846745] ip_tables: iptables: counters copy to user failed while replacing table [ 28.907039] [ 28.908891] ============================= [ 28.913035] WARNING: suspicious RCU usage [ 28.917244] 4.14.213-syzkaller #0 Not tainted [ 28.921739] ----------------------------- [ 28.925877] net/netfilter/nf_queue.c:227 suspicious rcu_dereference_check() usage! [ 28.933642] [ 28.933642] other info that might help us debug this: [ 28.933642] [ 28.941823] [ 28.941823] rcu_scheduler_active = 2, debug_locks = 1 [ 28.948530] 2 locks held by syz-executor646/8080: [ 28.953371] #0: (rcu_callback){....}, at: [] rcu_process_callbacks+0x84e/0x1180 [ 28.962651] #1: (&(&inst->lock)->rlock){+.-.}, at: [] nfqnl_flush+0x2f/0x2a0 [ 28.971640] [ 28.971640] stack backtrace: [ 28.976133] CPU: 1 PID: 8080 Comm: syz-executor646 Not tainted 4.14.213-syzkaller #0 [ 28.984095] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 28.993468] Call Trace: [ 28.996043] [ 28.998195] dump_stack+0x1b2/0x283 [ 29.001831] nf_reinject+0x56e/0x700 [ 29.005569] nfqnl_flush+0x1ab/0x2a0 [ 29.009284] instance_destroy_rcu+0x19/0x30 [ 29.013598] ? nfqnl_rcv_nl_event+0x290/0x290 [ 29.018088] rcu_process_callbacks+0x780/0x1180 [ 29.022758] ? note_gp_changes+0x2f0/0x2f0 [ 29.026988] ? sched_clock+0x2a/0x40 [ 29.030701] ? rcu_lockdep_current_cpu_online+0xed/0x140 [ 29.036149] __do_softirq+0x254/0xa1d [ 29.039950] ? check_preemption_disabled+0x35/0x240 [ 29.044972] irq_exit+0x193/0x240 [ 29.048424] smp_apic_timer_interrupt+0x141/0x5e0 [ 29.053269] apic_timer_interrupt+0x93/0xa0 [ 29.057584] [ 29.059820] RIP: 0010:_raw_spin_unlock_irqrestore+0xa3/0xe0 [ 29.065522] RSP: 0018:ffff8880a2e37718 EFLAGS: 00000286 ORIG_RAX: ffffffffffffff10 [ 29.073227] RAX: 1ffffffff11e1251 RBX: 0000000000000286 RCX: 0000000000000000 [ 29.080491] RDX: dffffc0000000000 RSI: 0000000000000001 RDI: 0000000000000286 [ 29.087760] RBP: ffffffff8bfe8ac8 R08: ffffffff8b992ba8 R09: 0000000000000000 [ 29.095022] R10: 0000000000000000 R11: 0000000000000000 R12: ffff88808ac00000 [ 29.102289] R13: 0000000000000000 R14: ffffffff8bfe8ac8 R15: 0000000000000000 [ 29.109574] debug_check_no_obj_freed+0x2c0/0x674 [ 29.114421] ? free_transhuge_page+0x1e8/0x290 [ 29.119005] ? debug_object_activate+0x490/0x490 [ 29.123867] ? rcu_lockdep_current_cpu_online+0xed/0x140 [ 29.129317] __free_pages_ok+0x215/0xeb0 [ 29.133380] ? _raw_spin_unlock_irqrestore+0x66/0xe0 [ 29.138484] ? free_transhuge_page+0x1e8/0x290 [ 29.143062] release_pages+0x779/0xbf0 [ 29.146985] ? __put_compound_page+0xb0/0xb0 [ 29.151388] ? free_pages_and_swap_cache+0x166/0x210 [ 29.156493] tlb_flush_mmu_free+0xc1/0x1a0 [ 29.160725] tlb_finish_mmu+0xf3/0x1e0 [ 29.164611] exit_mmap+0x290/0x4d0 [ 29.168148] ? SyS_remap_file_pages+0x6a0/0x6a0 [ 29.172917] ? kmem_cache_free+0x23a/0x2b0 [ 29.177150] ? __khugepaged_exit+0x29b/0x3c0 [ 29.181558] mmput+0xfa/0x420 [ 29.184663] do_exit+0x984/0x2850 [ 29.188114] ? futex_lock_pi_atomic+0x1f1/0x2e0 [ 29.192779] ? kmem_cache_alloc+0x124/0x3c0 [ 29.197100] ? mm_update_next_owner+0x5b0/0x5b0 [ 29.201765] ? get_signal+0x323/0x1ca0 [ 29.205654] ? lock_acquire+0x170/0x3f0 [ 29.209626] ? lock_downgrade+0x740/0x740 [ 29.213786] do_group_exit+0x100/0x2e0 [ 29.217670] get_signal+0x38d/0x1ca0 [ 29.221388] ? apparmor_file_alloc_security+0x129/0x800 [ 29.226752] do_signal+0x7c/0x1550 [ 29.230292] ? setup_sigcontext+0x820/0x820 [ 29.234622] ? __fd_install+0x227/0x5c0 [ 29.238619] ? get_unused_fd_flags+0xc0/0xc0 [ 29.243086] ? sock_alloc_file+0x1ae/0x2e0 [ 29.247322] ? SyS_futex+0x1da/0x290 [ 29.251033] ? SyS_futex+0x1e3/0x290 [ 29.254747] ? exit_to_usermode_loop+0x41/0x200 [ 29.259411] exit_to_usermode_loop+0x160/0x200 [ 29.263995] do_syscall_64+0x4a3/0x640 [ 29.267883] entry_SYSCALL_64_after_hwframe+0x46/0xbb [ 29.273066] RIP: 0033:0x4488c9 [ 29.276251] RSP: 002b:00007f91502a7d68 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca [ 29.283954] RAX: fffffffffffffe00 RBX: 00000000006ddc28 RCX: 00000000004488c9 [ 29.291228] RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00000000006ddc28 [ 29.298493] RBP: 00000000006ddc20 R08: 0000000000000000 R09: 0000000000000000 [ 29.305775] R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006ddc2c [ 29.313038] R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 [ 33.773389] net_ratelimit: 3841 callbacks suppressed [ 33.773393] ip_tables: iptables: counters copy to user failed while replacing table [ 33.787435] ip_tables: iptables: counters copy to user failed while replacing table [ 33.796651] ip_tables: iptables: counters copy to user failed while replacing table [ 33.805538] ip_tables: iptables: counters copy to user failed while replacing table [ 33.815070] ip_tables: iptables: counters copy to user failed while replacing table [ 33.823983] ip_tables: iptables: counters copy to user failed while replacing table [ 33.832001] ip_tables: iptables: counters copy to user failed while replacing table [ 33.840241] ip_tables: iptables: counters copy to user failed while replacing table [ 33.848880] ip_tables: iptables: counters copy to user failed while replacing table [ 33.857423] ip_tables: iptables: counters copy to user failed while replacing table [ 38.779448] net_ratelimit: 4068 callbacks suppressed [ 38.779451] ip_tables: iptables: counters copy to user failed while replacing table [ 38.793801] ip_tables: iptables: counters copy to user failed while replacing table [ 38.804119] ip_tables: iptables: counters copy to user failed while replacing table [ 38.812361] ip_tables: iptables: counters copy to user failed while replacing table [ 38.820876] ip_tables: iptables: counters copy to user failed while replacing table [ 38.828901] ip_tables: iptables: counters copy to user failed while replacing table [ 38.837916] ip_tables: iptables: counters copy to user failed while replacing table [ 38.847503] ip_tables: iptables: counters copy to user failed while replacing table [ 38.855896] ip_tables: iptables: counters copy to user failed while replacing table [ 38.866067] ip_tables: iptables: counters copy to user failed while replacing table