[ OK ] Reached target Graphical Interface. Starting Update UTMP about System Runlevel Changes... [ OK ] Started Update UTMP about System Runlevel Changes. Starting Load/Save RF Kill Switch Status... [ OK ] Started Load/Save RF Kill Switch Status. Debian GNU/Linux 9 syzkaller ttyS0 Warning: Permanently added '10.128.0.198' (ECDSA) to the list of known hosts. executing program syzkaller login: [ 32.010132] [ 32.011891] ============================= [ 32.016042] WARNING: suspicious RCU usage [ 32.020164] 4.14.290-syzkaller #0 Not tainted [ 32.024881] ----------------------------- [ 32.029012] net/sched/act_sample.c:95 suspicious rcu_dereference_protected() usage! [ 32.036840] [ 32.036840] other info that might help us debug this: [ 32.036840] [ 32.045180] [ 32.045180] rcu_scheduler_active = 2, debug_locks = 1 [ 32.051931] 1 lock held by syz-executor344/7979: [ 32.056666] #0: (rtnl_mutex){+.+.}, at: [] rtnetlink_rcv_msg+0x31d/0xb10 [ 32.065290] [ 32.065290] stack backtrace: [ 32.069772] CPU: 0 PID: 7979 Comm: syz-executor344 Not tainted 4.14.290-syzkaller #0 [ 32.077638] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/22/2022 [ 32.086966] Call Trace: [ 32.089534] dump_stack+0x1b2/0x281 [ 32.093139] tcf_sample_init+0x71c/0x8c0 [ 32.097178] ? tcf_sample_cleanup_rcu+0x60/0x60 [ 32.101826] tcf_action_init_1+0x51a/0x9e0 [ 32.106040] ? tcf_action_dump_old+0x80/0x80 [ 32.110429] ? nla_parse+0x157/0x1f0 [ 32.114116] tcf_action_init+0x26d/0x400 [ 32.118158] ? tcf_action_init_1+0x9e0/0x9e0 [ 32.122551] ? memset+0x20/0x40 [ 32.125804] ? nla_parse+0x157/0x1f0 [ 32.129492] tc_ctl_action+0x2e3/0x510 [ 32.133357] ? tca_action_gd+0x790/0x790 [ 32.137391] ? rtnetlink_rcv_msg+0x2e8/0xb10 [ 32.141777] ? tca_action_gd+0x790/0x790 [ 32.145812] rtnetlink_rcv_msg+0x3be/0xb10 [ 32.150023] ? rtnl_calcit.isra.0+0x3a0/0x3a0 [ 32.154495] ? __netlink_lookup+0x345/0x5d0 [ 32.158795] netlink_rcv_skb+0x125/0x390 [ 32.162830] ? rtnl_calcit.isra.0+0x3a0/0x3a0 [ 32.167297] ? netlink_ack+0x9a0/0x9a0 [ 32.171163] netlink_unicast+0x437/0x610 [ 32.175208] ? netlink_sendskb+0xd0/0xd0 [ 32.179245] ? __check_object_size+0x179/0x230 [ 32.183800] netlink_sendmsg+0x648/0xbc0 [ 32.187836] ? nlmsg_notify+0x1b0/0x1b0 [ 32.191796] ? kernel_recvmsg+0x210/0x210 [ 32.195923] ? security_socket_sendmsg+0x83/0xb0 [ 32.200663] ? nlmsg_notify+0x1b0/0x1b0 [ 32.204614] sock_sendmsg+0xb5/0x100 [ 32.208323] ___sys_sendmsg+0x6c8/0x800 [ 32.212279] ? copy_msghdr_from_user+0x3b0/0x3b0 [ 32.217015] ? lock_downgrade+0x740/0x740 [ 32.221139] ? __lru_cache_add+0x178/0x250 [ 32.225379] ? do_raw_spin_unlock+0x164/0x220 [ 32.229879] ? _raw_spin_unlock+0x29/0x40 [ 32.234006] ? do_huge_pmd_anonymous_page+0x72e/0x1700 [ 32.239259] ? prep_transhuge_page+0xa0/0xa0 [ 32.243641] ? _raw_spin_unlock+0x29/0x40 [ 32.247773] ? __pmd_alloc+0x27f/0x3f0 [ 32.251641] ? __handle_mm_fault+0x80f/0x4620 [ 32.256119] ? lock_downgrade+0x740/0x740 [ 32.260253] ? vm_insert_page+0x7c0/0x7c0 [ 32.264374] ? __fdget+0x167/0x1f0 [ 32.267901] ? sockfd_lookup_light+0xb2/0x160 [ 32.272369] __sys_sendmsg+0xa3/0x120 [ 32.276152] ? SyS_shutdown+0x160/0x160 [ 32.280107] ? up_read+0x17/0x30 [ 32.283462] ? __do_page_fault+0x159/0xad0 [ 32.287673] SyS_sendmsg+0x27/0x40 [ 32.291194] ? __sys_sendmsg+0x120/0x120 [ 32.295232] do_syscall_64+0x1d5/0x640 [ 32.299096] entry_SYSCALL_64_after_hwframe+0x46/0xbb [ 32.304260] RIP: 0033:0x7f9391bd0259 [ 32.307944] RSP: 002b:00007ffdd93c878