[ 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 '10.128.0.217' (ECDSA) to the list of known hosts. executing program syzkaller login: [ 31.401624] [ 31.403419] ============================= [ 31.407539] WARNING: suspicious RCU usage [ 31.412574] 4.14.209-syzkaller #0 Not tainted [ 31.417058] ----------------------------- [ 31.421847] net/tipc/bearer.c:177 suspicious rcu_dereference_protected() usage! [ 31.429765] [ 31.429765] other info that might help us debug this: [ 31.429765] [ 31.437894] [ 31.437894] rcu_scheduler_active = 2, debug_locks = 1 [ 31.445264] 2 locks held by syz-executor760/7989: [ 31.450480] #0: (cb_lock){++++}, at: [] genl_rcv+0x15/0x40 [ 31.457836] #1: (genl_mutex){+.+.}, at: [] genl_rcv_msg+0x112/0x140 [ 31.466508] [ 31.466508] stack backtrace: [ 31.471376] CPU: 0 PID: 7989 Comm: syz-executor760 Not tainted 4.14.209-syzkaller #0 [ 31.479239] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 31.488594] Call Trace: [ 31.491171] dump_stack+0x1b2/0x283 [ 31.494784] tipc_bearer_find+0x1ff/0x2f0 [ 31.499961] tipc_nl_compat_link_set+0x40b/0xb90 [ 31.504690] ? __alloc_skb+0x3dc/0x510 [ 31.508551] tipc_nl_compat_doit+0x192/0x5d0 [ 31.512941] ? tipc_nl_compat_link_set+0xb90/0xb90 [ 31.517850] ? security_capable+0x88/0xb0 [ 31.521987] ? ns_capable_common+0x127/0x150 [ 31.526370] tipc_nl_compat_recv+0xa0b/0xae0 [ 31.530774] ? tipc_nl_compat_dumpit+0x7a0/0x7a0 [ 31.535504] ? tipc_nl_node_dump+0xc20/0xc20 [ 31.539887] ? __tipc_add_link_prop.isra.0+0x190/0x190 [ 31.545135] ? lock_downgrade+0x740/0x740 [ 31.549265] genl_family_rcv_msg+0x572/0xb20 [ 31.553647] ? __lock_acquire+0x5fc/0x3f20 [ 31.557854] ? genl_rcv+0x40/0x40 [ 31.561284] ? __ww_mutex_wakeup_for_backoff+0x210/0x210 [ 31.566796] ? trace_hardirqs_on+0x10/0x10 [ 31.571005] ? sock_sendmsg+0xb5/0x100 [ 31.574869] genl_rcv_msg+0xaf/0x140 [ 31.578557] netlink_rcv_skb+0x125/0x390 [ 31.582603] ? genl_family_rcv_msg+0xb20/0xb20 [ 31.587159] ? netlink_ack+0x9a0/0x9a0 [ 31.591032] ? lock_acquire+0x170/0x3f0 [ 31.594992] genl_rcv+0x24/0x40 [ 31.598244] netlink_unicast+0x437/0x610 [ 31.602293] ? netlink_sendskb+0xd0/0xd0 [ 31.606327] ? __check_object_size+0x179/0x22c [ 31.610882] netlink_sendmsg+0x62e/0xb80 [ 31.614936] ? nlmsg_notify+0x170/0x170 [ 31.618907] ? kernel_recvmsg+0x210/0x210 [ 31.623035] ? security_socket_sendmsg+0x83/0xb0 [ 31.627764] ? nlmsg_notify+0x170/0x170 [ 31.631724] sock_sendmsg+0xb5/0x100 [ 31.635412] ___sys_sendmsg+0x6c8/0x800 [ 31.639361] ? copy_msghdr_from_user+0x3b0/0x3b0 [ 31.644089] ? __lock_acquire+0x5fc/0x3f20 [ 31.648300] ? __dentry_kill+0x3f7/0x550 [ 31.652334] ? trace_hardirqs_on+0x10/0x10 [ 31.656583] ? rcu_lockdep_current_cpu_online+0xed/0x140 [ 31.662046] ? dentry_free+0xc6/0x120 [ 31.665835] ? rcu_read_lock_sched_held+0x16c/0x1d0 [ 31.670830] ? kmem_cache_free+0x23a/0x2b0 [ 31.675050] ? mntput_no_expire+0xc7/0x910 [ 31.679268] ? lock_acquire+0x170/0x3f0 [ 31.683216] ? __fdget+0x167/0x1f0 [ 31.686731] ? sockfd_lookup_light+0xb2/0x160 [ 31.691199] __sys_sendmsg+0xa3/0x120 [ 31.694991] ? SyS_shutdown+0x160/0x160 [ 31.698962] SyS_sendmsg+0x27/0x40 [ 31.702481] ? __sys_sendmsg+0x120/0x120 [ 31.706548] do_syscall_64+0x1d5/0x640 [ 31.710418] entry_SYSCALL_64_after_hwframe+0x46/0xbb [ 31.715583] RIP: 0033:0x440909 [ 31.718748] RSP: 002b:00007ffdbbb65c38 EFLAGS: 00000246 ORIG_RAX: 000000000000002e [ 31.726433] RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 0000000000440909 [ 31.733678] RDX: 0000000000000000 RSI: 0000000020000100 RDI: 0000000000000003 [ 31.740924] RBP: 00000000006ca018 R08: 0000000000000000 R09: 00000000004002c8 [ 31.748169] R10: 0000000000001800 R11: 0000000000000246