[ OK ] Started Getty on tty6. [ OK ] Started Getty on tty5. [ OK ] Started Getty on tty4. [ OK ] Reached target Login Prompts. [ 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 Load/Save RF Kill Switch Status. [ OK ] Started Update UTMP about System Runlevel Changes. Debian GNU/Linux 9 syzkaller ttyS0 Warning: Permanently added '10.128.1.90' (ECDSA) to the list of known hosts. executing program syzkaller login: [ 27.970698] [ 27.972379] ============================= [ 27.977278] WARNING: suspicious RCU usage [ 27.981419] 4.14.277-syzkaller #0 Not tainted [ 27.986501] ----------------------------- [ 27.990633] net/sched/act_sample.c:95 suspicious rcu_dereference_protected() usage! [ 27.999152] [ 27.999152] other info that might help us debug this: [ 27.999152] [ 28.007827] [ 28.007827] rcu_scheduler_active = 2, debug_locks = 1 [ 28.014923] 1 lock held by syz-executor212/7957: [ 28.019660] #0: (rtnl_mutex){+.+.}, at: [] rtnetlink_rcv_msg+0x31d/0xb10 [ 28.028813] [ 28.028813] stack backtrace: [ 28.033679] CPU: 1 PID: 7957 Comm: syz-executor212 Not tainted 4.14.277-syzkaller #0 [ 28.041541] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 28.050870] Call Trace: [ 28.053436] dump_stack+0x1b2/0x281 [ 28.057040] tcf_sample_init+0x71c/0x8c0 [ 28.061082] ? tcf_sample_cleanup_rcu+0x60/0x60 [ 28.065731] tcf_action_init_1+0x51a/0x9e0 [ 28.069946] ? tcf_action_dump_old+0x80/0x80 [ 28.074337] ? nla_parse+0x157/0x1f0 [ 28.078025] tcf_action_init+0x26d/0x400 [ 28.082063] ? tcf_action_init_1+0x9e0/0x9e0 [ 28.086455] ? memset+0x20/0x40 [ 28.089712] ? nla_parse+0x157/0x1f0 [ 28.093400] tc_ctl_action+0x2e3/0x510 [ 28.097262] ? tca_action_gd+0x790/0x790 [ 28.101297] ? rtnetlink_rcv_msg+0x2e8/0xb10 [ 28.105683] ? tca_action_gd+0x790/0x790 [ 28.109721] rtnetlink_rcv_msg+0x3be/0xb10 [ 28.113930] ? rtnl_calcit.isra.0+0x3a0/0x3a0 [ 28.118399] ? __netlink_lookup+0x345/0x5d0 [ 28.122700] netlink_rcv_skb+0x125/0x390 [ 28.126739] ? rtnl_calcit.isra.0+0x3a0/0x3a0 [ 28.131210] ? netlink_ack+0x9a0/0x9a0 [ 28.135077] netlink_unicast+0x437/0x610 [ 28.139114] ? netlink_sendskb+0xd0/0xd0 [ 28.143151] ? __check_object_size+0x179/0x230 [ 28.147708] netlink_sendmsg+0x648/0xbc0 [ 28.151749] ? nlmsg_notify+0x1b0/0x1b0 [ 28.155698] ? kernel_recvmsg+0x210/0x210 [ 28.159821] ? security_socket_sendmsg+0x83/0xb0 [ 28.164550] ? nlmsg_notify+0x1b0/0x1b0 [ 28.168496] sock_sendmsg+0xb5/0x100 [ 28.172186] ___sys_sendmsg+0x6c8/0x800 [ 28.176138] ? copy_msghdr_from_user+0x3b0/0x3b0 [ 28.180869] ? lock_downgrade+0x740/0x740 [ 28.185007] ? __lru_cache_add+0x178/0x250 [ 28.189215] ? do_raw_spin_unlock+0x164/0x220 [ 28.193687] ? _raw_spin_unlock+0x29/0x40 [ 28.197812] ? do_huge_pmd_anonymous_page+0x72e/0x1700 [ 28.203065] ? prep_transhuge_page+0xa0/0xa0 [ 28.207445] ? _raw_spin_unlock+0x29/0x40 [ 28.211568] ? __pmd_alloc+0x27f/0x3f0 [ 28.215432] ? __handle_mm_fault+0x80f/0x4620 [ 28.219906] ? lock_downgrade+0x740/0x740 [ 28.224028] ? vm_insert_page+0x7c0/0x7c0 [ 28.228149] ? __fdget+0x167/0x1f0 [ 28.231666] ? sockfd_lookup_light+0xb2/0x160 [ 28.236155] __sys_sendmsg+0xa3/0x120 [ 28.239929] ? SyS_shutdown+0x160/0x160 [ 28.243881] ? up_read+0x17/0x30 [ 28.247225] ? __do_page_fault+0x159/0xad0 [ 28.251433] SyS_sendmsg+0x27/0x40 [ 28.254945] ? __sys_sendmsg+0x120/0x120 [ 28.258981] do_syscall_64+0x1d5/0x640 [ 28.262846] entry_SYSCALL_64_after_hwframe+0x46/0xbb [ 28.268008] RIP: 0033:0x7f9c7503b259 [