[ 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 '10.128.0.116' (ECDSA) to the list of known hosts. executing program syzkaller login: [ 31.030416] [ 31.032215] ============================= [ 31.036556] WARNING: suspicious RCU usage [ 31.040775] 4.14.231-syzkaller #0 Not tainted [ 31.046568] ----------------------------- [ 31.050710] net/tipc/bearer.c:177 suspicious rcu_dereference_protected() usage! [ 31.059073] [ 31.059073] other info that might help us debug this: [ 31.059073] [ 31.067365] [ 31.067365] rcu_scheduler_active = 2, debug_locks = 1 [ 31.074486] 2 locks held by syz-executor083/7997: [ 31.079343] #0: (cb_lock){++++}, at: [] genl_rcv+0x15/0x40 [ 31.086803] #1: (genl_mutex){+.+.}, at: [] genl_rcv_msg+0x112/0x140 [ 31.095027] [ 31.095027] stack backtrace: [ 31.099522] CPU: 0 PID: 7997 Comm: syz-executor083 Not tainted 4.14.231-syzkaller #0 [ 31.107383] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 31.116724] Call Trace: [ 31.119296] dump_stack+0x1b2/0x281 [ 31.122909] tipc_bearer_find+0x1ff/0x2f0 [ 31.127039] tipc_nl_compat_link_set+0x40b/0xb90 [ 31.131802] ? __alloc_skb+0x3dc/0x510 [ 31.135698] tipc_nl_compat_doit+0x192/0x5d0 [ 31.140117] ? tipc_nl_compat_link_set+0xb90/0xb90 [ 31.145035] ? security_capable+0x88/0xb0 [ 31.149172] ? ns_capable_common+0x127/0x150 [ 31.153564] tipc_nl_compat_recv+0xa0b/0xae0 [ 31.157966] ? tipc_nl_compat_dumpit+0x7a0/0x7a0 [ 31.162704] ? tipc_nl_node_dump+0xc20/0xc20 [ 31.167105] ? __tipc_add_link_prop.isra.0+0x190/0x190 [ 31.172385] ? lock_downgrade+0x740/0x740 [ 31.176518] genl_family_rcv_msg+0x572/0xb20 [ 31.180910] ? __lock_acquire+0x5fc/0x3f20 [ 31.185214] ? genl_rcv+0x40/0x40 [ 31.188653] ? __ww_mutex_wakeup_for_backoff+0x210/0x210 [ 31.194206] ? trace_hardirqs_on+0x10/0x10 [ 31.198425] ? sock_sendmsg+0xb5/0x100 [ 31.202319] genl_rcv_msg+0xaf/0x140 [ 31.206124] netlink_rcv_skb+0x125/0x390 [ 31.210167] ? genl_family_rcv_msg+0xb20/0xb20 [ 31.214729] ? netlink_ack+0x9a0/0x9a0 [ 31.218594] ? lock_acquire+0x170/0x3f0 [ 31.222574] genl_rcv+0x24/0x40 [ 31.225850] netlink_unicast+0x437/0x610 [ 31.229906] ? netlink_sendskb+0xd0/0xd0 [ 31.233955] ? __check_object_size+0x179/0x230 [ 31.238542] netlink_sendmsg+0x62e/0xb80 [ 31.242638] ? nlmsg_notify+0x170/0x170 [ 31.246604] ? kernel_recvmsg+0x210/0x210 [ 31.250741] ? security_socket_sendmsg+0x83/0xb0 [ 31.255496] ? nlmsg_notify+0x170/0x170 [ 31.259467] sock_sendmsg+0xb5/0x100 [ 31.263172] ___sys_sendmsg+0x6c8/0x800 [ 31.267130] ? copy_msghdr_from_user+0x3b0/0x3b0 [ 31.271871] ? __lock_acquire+0x5fc/0x3f20 [ 31.276112] ? __dentry_kill+0x3f7/0x550 [ 31.280166] ? trace_hardirqs_on+0x10/0x10 [ 31.284407] ? rcu_lockdep_current_cpu_online+0xed/0x140 [ 31.289837] ? dentry_free+0xc6/0x120 [ 31.293631] ? rcu_read_lock_sched_held+0x16c/0x1d0 [ 31.298627] ? kmem_cache_free+0x23a/0x2b0 [ 31.302864] ? mntput_no_expire+0xc7/0x910 [ 31.307093] ? lock_acquire+0x170/0x3f0 [ 31.311043] ? __fdget+0x167/0x1f0 [ 31.314559] ? sockfd_lookup_light+0xb2/0x160 [ 31.319060] __sys_sendmsg+0xa3/0x120 [ 31.322856] ? SyS_shutdown+0x160/0x160 [ 31.326813] SyS_sendmsg+0x27/0x40 [ 31.330330] ? __sys_sendmsg+0x120/0x120 [ 31.334387] do_syscall_64+0x1d5/0x640 [ 31.338258] entry_SYSCALL_64_after_hwframe+0x46/0xbb [ 31.343426] RIP: 0033:0x43fa09 [ 31.346607] RSP: 002b:00007ffe5ba2ee18 EFLAGS: 00000246 ORIG_RAX: 000000000000002e [ 31.354311] RAX: ffffffffffffffda RBX: 00000000004004a0 RCX: 000000000043fa09 [ 31.361599] RDX: 0000000000000000 RSI: 0000000020000400 RDI: 0000000000000003 [ 31.368848] RBP: 0000000000403470 R08: 0000000000000000 R09: 00000000004004a0 [ 31.376123] R10: 0000000000001800 R11: 0000000000000246 R12: 00000