[ 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. [ OK ] Started Load/Save RF Kill Switch Status. Debian GNU/Linux 9 syzkaller ttyS0 Warning: Permanently added '10.128.1.34' (ECDSA) to the list of known hosts. executing program syzkaller login: [ 29.376126] [ 29.377910] ============================= [ 29.382499] WARNING: suspicious RCU usage [ 29.387867] 4.14.225-syzkaller #0 Not tainted [ 29.392653] ----------------------------- [ 29.398090] net/tipc/bearer.c:177 suspicious rcu_dereference_protected() usage! [ 29.406835] [ 29.406835] other info that might help us debug this: [ 29.406835] [ 29.415285] [ 29.415285] rcu_scheduler_active = 2, debug_locks = 1 [ 29.422934] 2 locks held by syz-executor941/7942: [ 29.428327] #0: (cb_lock){++++}, at: [] genl_rcv+0x15/0x40 [ 29.436208] #1: (genl_mutex){+.+.}, at: [] genl_rcv_msg+0x112/0x140 [ 29.444367] [ 29.444367] stack backtrace: [ 29.449824] CPU: 1 PID: 7942 Comm: syz-executor941 Not tainted 4.14.225-syzkaller #0 [ 29.457904] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 29.467939] Call Trace: [ 29.470536] dump_stack+0x1b2/0x281 [ 29.474301] tipc_bearer_find+0x1ff/0x2f0 [ 29.478585] tipc_nl_compat_link_set+0x40b/0xb90 [ 29.483605] ? __alloc_skb+0x3dc/0x510 [ 29.487612] tipc_nl_compat_doit+0x192/0x5d0 [ 29.492068] ? tipc_nl_compat_link_set+0xb90/0xb90 [ 29.496989] ? security_capable+0x88/0xb0 [ 29.501128] ? ns_capable_common+0x127/0x150 [ 29.505536] tipc_nl_compat_recv+0xa0b/0xae0 [ 29.509944] ? tipc_nl_compat_dumpit+0x7a0/0x7a0 [ 29.515006] ? tipc_nl_node_dump+0xc20/0xc20 [ 29.519412] ? __tipc_add_link_prop.isra.0+0x190/0x190 [ 29.524684] ? lock_downgrade+0x740/0x740 [ 29.528857] genl_family_rcv_msg+0x572/0xb20 [ 29.533259] ? __lock_acquire+0x5fc/0x3f20 [ 29.537629] ? genl_rcv+0x40/0x40 [ 29.541084] ? __ww_mutex_wakeup_for_backoff+0x210/0x210 [ 29.546897] ? trace_hardirqs_on+0x10/0x10 [ 29.551127] ? sock_sendmsg+0xb5/0x100 [ 29.555191] genl_rcv_msg+0xaf/0x140 [ 29.558900] netlink_rcv_skb+0x125/0x390 [ 29.563113] ? genl_family_rcv_msg+0xb20/0xb20 [ 29.567796] ? netlink_ack+0x9a0/0x9a0 [ 29.571980] ? lock_acquire+0x170/0x3f0 [ 29.576134] genl_rcv+0x24/0x40 [ 29.579500] netlink_unicast+0x437/0x610 [ 29.583553] ? netlink_sendskb+0xd0/0xd0 [ 29.587743] ? __check_object_size+0x179/0x230 [ 29.592464] netlink_sendmsg+0x62e/0xb80 [ 29.596902] ? nlmsg_notify+0x170/0x170 [ 29.600872] ? kernel_recvmsg+0x210/0x210 [ 29.605322] ? security_socket_sendmsg+0x83/0xb0 [ 29.610092] ? nlmsg_notify+0x170/0x170 [ 29.614190] sock_sendmsg+0xb5/0x100 [ 29.617899] ___sys_sendmsg+0x6c8/0x800 [ 29.622096] ? copy_msghdr_from_user+0x3b0/0x3b0 [ 29.626860] ? __lock_acquire+0x5fc/0x3f20 [ 29.631091] ? __dentry_kill+0x3f7/0x550 [ 29.635459] ? trace_hardirqs_on+0x10/0x10 [ 29.639691] ? rcu_lockdep_current_cpu_online+0xed/0x140 [ 29.645140] ? dentry_free+0xc6/0x120 [ 29.649030] ? rcu_read_lock_sched_held+0x16c/0x1d0 [ 29.654092] ? kmem_cache_free+0x23a/0x2b0 [ 29.658622] ? mntput_no_expire+0xc7/0x910 [ 29.663071] ? lock_acquire+0x170/0x3f0 [ 29.667259] ? __fdget+0x167/0x1f0 [ 29.670918] ? sockfd_lookup_light+0xb2/0x160 [ 29.675411] __sys_se