can: request_module (can-proto-5) failed. BUG: sleeping function called from invalid context at net/core/sock.c:2772 in_atomic(): 1, irqs_disabled(): 0, pid: 699, name: kworker/u4:4 5 locks held by kworker/u4:4/699: #0: ((wq_completion)"%s""netns"){+.+.}, at: [<000000000c30e438>] process_one_work+0xaaf/0x1af0 kernel/workqueue.c:2084 #1: (net_cleanup_work){+.+.}, at: [<000000003149867d>] process_one_work+0xb01/0x1af0 kernel/workqueue.c:2088 syz-executor6 (5667) used greatest stack depth: 14928 bytes left #2: (net_sem){++++}, at: [<0000000086664b36>] cleanup_net+0x23f/0xd20 net/core/net_namespace.c:494 #3: (net_mutex){+.+.}, at: [<0000000090f2170f>] cleanup_net+0xa7d/0xd20 net/core/net_namespace.c:496 #4: (&(&srv->idr_lock)->rlock){+...}, at: [<0000000095e89137>] spin_lock_bh include/linux/spinlock.h:315 [inline] #4: (&(&srv->idr_lock)->rlock){+...}, at: [<0000000095e89137>] tipc_topsrv_stop+0x231/0x610 net/tipc/topsrv.c:685 CPU: 1 PID: 699 Comm: kworker/u4:4 Not tainted 4.16.0-rc1+ #232 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: netns cleanup_net Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0x194/0x257 lib/dump_stack.c:53 ___might_sleep+0x2b2/0x470 kernel/sched/core.c:6128 can: request_module (can-proto-5) failed. __might_sleep+0x95/0x190 kernel/sched/core.c:6081 lock_sock_nested+0x37/0x110 net/core/sock.c:2772 lock_sock include/net/sock.h:1463 [inline] tipc_release+0x103/0xff0 net/tipc/socket.c:572 sock_release+0x8d/0x1e0 net/socket.c:594 tipc_topsrv_stop+0x3c0/0x610 net/tipc/topsrv.c:696 tipc_exit_net+0x15/0x40 net/tipc/core.c:96 ops_exit_list.isra.6+0xae/0x150 net/core/net_namespace.c:148 cleanup_net+0x6ba/0xd20 net/core/net_namespace.c:529 process_one_work+0xbbf/0x1af0 kernel/workqueue.c:2113 worker_thread+0x223/0x1990 kernel/workqueue.c:2247 kthread+0x33c/0x400 kernel/kthread.c:238 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:429 xt_connbytes: Forcing CT accounting to be enabled netlink: 2 bytes leftover after parsing attributes in process `syz-executor1'. sit: non-ECT from 0.0.0.0 with TOS=0x3 sit: non-ECT from 0.0.0.0 with TOS=0x3 netlink: 2 bytes leftover after parsing attributes in process `syz-executor1'. sock: sock_set_timeout: `syz-executor1' (pid 6006) tries to set negative timeout sock: sock_set_timeout: `syz-executor1' (pid 6006) tries to set negative timeout netlink: 'syz-executor4': attribute type 16 has an invalid length. netlink: 'syz-executor4': attribute type 16 has an invalid length. xt_CT: netfilter: NOTRACK target is deprecated, use CT instead or upgrade iptables Can not set IPV6_FL_F_REFLECT if flowlabel_consistency sysctl is enable sctp: [Deprecated]: syz-executor1 (pid 6225) Use of struct sctp_assoc_value in delayed_ack socket option. Use struct sctp_sack_info instead Can not set IPV6_FL_F_REFLECT if flowlabel_consistency sysctl is enable ====================================================== WARNING: possible circular locking dependency detected 4.16.0-rc1+ #232 Tainted: G W ------------------------------------------------------ syz-executor2/6262 is trying to acquire lock: (rtnl_mutex){+.+.}, at: [<0000000015b25120>] rtnl_lock+0x17/0x20 net/core/rtnetlink.c:74 but task is already holding lock: (&xt[i].mutex){+.+.}, at: [<000000007f76596d>] xt_find_table_lock+0x3e/0x3e0 net/netfilter/x_tables.c:1046 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (&xt[i].mutex){+.+.}: __mutex_lock_common kernel/locking/mutex.c:756 [inline] __mutex_lock+0x16f/0x1a80 kernel/locking/mutex.c:893 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908 xt_find_table_lock+0x3e/0x3e0 net/netfilter/x_tables.c:1046 xt_request_find_table_lock+0x28/0xc0 net/netfilter/x_tables.c:1093 get_info+0x154/0x690 net/ipv6/netfilter/ip6_tables.c:989 do_arpt_get_ctl+0x2a9/0xa00 net/ipv4/netfilter/arp_tables.c:1481 nf_sockopt net/netfilter/nf_sockopt.c:104 [inline] nf_getsockopt+0x6a/0xc0 net/netfilter/nf_sockopt.c:122 ip_getsockopt+0x15c/0x220 net/ipv4/ip_sockglue.c:1573 tcp_getsockopt+0x82/0xd0 net/ipv4/tcp.c:3359 sock_common_getsockopt+0x95/0xd0 net/core/sock.c:2938 SYSC_getsockopt net/socket.c:1881 [inline] SyS_getsockopt+0x178/0x340 net/socket.c:1863 do_syscall_64+0x282/0x940 arch/x86/entry/common.c:287 entry_SYSCALL_64_after_hwframe+0x26/0x9b -> #1 (sk_lock-AF_INET){+.+.}: lock_sock_nested+0xc2/0x110 net/core/sock.c:2781 lock_sock include/net/sock.h:1463 [inline] do_ip_setsockopt.isra.12+0x1d9/0x3210 net/ipv4/ip_sockglue.c:648 ip_setsockopt+0x3a/0xa0 net/ipv4/ip_sockglue.c:1254 sctp_setsockopt+0x2b6/0x61d0 net/sctp/socket.c:4104 sock_common_setsockopt+0x95/0xd0 net/core/sock.c:2979 SYSC_setsockopt net/socket.c:1850 [inline] SyS_setsockopt+0x189/0x360 net/socket.c:1829 do_syscall_64+0x282/0x940 arch/x86/entry/common.c:287 entry_SYSCALL_64_after_hwframe+0x26/0x9b -> #0 (rtnl_mutex){+.+.}: lock_acquire+0x1d5/0x580 kernel/locking/lockdep.c:3920 __mutex_lock_common kernel/locking/mutex.c:756 [inline] __mutex_lock+0x16f/0x1a80 kernel/locking/mutex.c:893 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908 rtnl_lock+0x17/0x20 net/core/rtnetlink.c:74 unregister_netdevice_notifier+0x91/0x4e0 net/core/dev.c:1673 tee_tg_destroy+0x61/0xc0 net/netfilter/xt_TEE.c:123 cleanup_entry+0x218/0x350 net/ipv4/netfilter/ip_tables.c:654 __do_replace+0x79d/0xa50 net/ipv4/netfilter/ip_tables.c:1089 do_replace net/ipv4/netfilter/ip_tables.c:1145 [inline] do_ipt_set_ctl+0x40f/0x5f0 net/ipv4/netfilter/ip_tables.c:1675 nf_sockopt net/netfilter/nf_sockopt.c:106 [inline] nf_setsockopt+0x67/0xc0 net/netfilter/nf_sockopt.c:115 ip_setsockopt+0x97/0xa0 net/ipv4/ip_sockglue.c:1261 udp_setsockopt+0x45/0x80 net/ipv4/udp.c:2401 ipv6_setsockopt+0xa0/0x130 net/ipv6/ipv6_sockglue.c:917 sctp_setsockopt+0x2b6/0x61d0 net/sctp/socket.c:4104 sock_common_setsockopt+0x95/0xd0 net/core/sock.c:2979 SYSC_setsockopt net/socket.c:1850 [inline] SyS_setsockopt+0x189/0x360 net/socket.c:1829 do_syscall_64+0x282/0x940 arch/x86/entry/common.c:287 entry_SYSCALL_64_after_hwframe+0x26/0x9b other info that might help us debug this: Chain exists of: rtnl_mutex --> sk_lock-AF_INET --> &xt[i].mutex Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&xt[i].mutex); lock(sk_lock-AF_INET); lock(&xt[i].mutex); lock(rtnl_mutex); *** DEADLOCK *** 1 lock held by syz-executor2/6262: #0: (&xt[i].mutex){+.+.}, at: [<000000007f76596d>] xt_find_table_lock+0x3e/0x3e0 net/netfilter/x_tables.c:1046 stack backtrace: CPU: 1 PID: 6262 Comm: syz-executor2 Tainted: G W 4.16.0-rc1+ #232 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0x194/0x257 lib/dump_stack.c:53 print_circular_bug.isra.38+0x2cd/0x2dc kernel/locking/lockdep.c:1223 check_prev_add kernel/locking/lockdep.c:1863 [inline] check_prevs_add kernel/locking/lockdep.c:1976 [inline] validate_chain kernel/locking/lockdep.c:2417 [inline] __lock_acquire+0x30a8/0x3e00 kernel/locking/lockdep.c:3431 lock_acquire+0x1d5/0x580 kernel/locking/lockdep.c:3920 __mutex_lock_common kernel/locking/mutex.c:756 [inline] __mutex_lock+0x16f/0x1a80 kernel/locking/mutex.c:893 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908 rtnl_lock+0x17/0x20 net/core/rtnetlink.c:74 unregister_netdevice_notifier+0x91/0x4e0 net/core/dev.c:1673 tee_tg_destroy+0x61/0xc0 net/netfilter/xt_TEE.c:123 cleanup_entry+0x218/0x350 net/ipv4/netfilter/ip_tables.c:654 __do_replace+0x79d/0xa50 net/ipv4/netfilter/ip_tables.c:1089 do_replace net/ipv4/netfilter/ip_tables.c:1145 [inline] do_ipt_set_ctl+0x40f/0x5f0 net/ipv4/netfilter/ip_tables.c:1675 nf_sockopt net/netfilter/nf_sockopt.c:106 [inline] nf_setsockopt+0x67/0xc0 net/netfilter/nf_sockopt.c:115 ip_setsockopt+0x97/0xa0 net/ipv4/ip_sockglue.c:1261 udp_setsockopt+0x45/0x80 net/ipv4/udp.c:2401 ipv6_setsockopt+0xa0/0x130 net/ipv6/ipv6_sockglue.c:917 sctp_setsockopt+0x2b6/0x61d0 net/sctp/socket.c:4104 sock_common_setsockopt+0x95/0xd0 net/core/sock.c:2979 SYSC_setsockopt net/socket.c:1850 [inline] SyS_setsockopt+0x189/0x360 net/socket.c:1829 do_syscall_64+0x282/0x940 arch/x86/entry/common.c:287 entry_SYSCALL_64_after_hwframe+0x26/0x9b RIP: 0033:0x453d69 RSP: 002b:00007f3d0f959c68 EFLAGS: 00000246 ORIG_RAX: 0000000000000036 RAX: ffffffffffffffda RBX: 00007f3d0f95a6d4 RCX: 0000000000453d69 RDX: 0000000000000040 RSI: 0000000000000000 RDI: 0000000000000013 RBP: 000000000072bf58 R08: 00000000000003a0 R09: 0000000000000000 R10: 0000000020015000 R11: 0000000000000246 R12: 00000000ffffffff R13: 00000000000004d6 R14: 00000000006f74b0 R15: 0000000000000001 sctp: [Deprecated]: syz-executor4 (pid 6283) Use of struct sctp_assoc_value in delayed_ack socket option. Use struct sctp_sack_info instead NFQUEUE: number of total queues is 0 NFQUEUE: number of total queues is 0 BUG: sleeping function called from invalid context at net/core/sock.c:2772 in_atomic(): 1, irqs_disabled(): 0, pid: 699, name: kworker/u4:4 INFO: lockdep is turned off. CPU: 0 PID: 699 Comm: kworker/u4:4 Tainted: G W 4.16.0-rc1+ #232 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: netns cleanup_net Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0x194/0x257 lib/dump_stack.c:53 ___might_sleep+0x2b2/0x470 kernel/sched/core.c:6128 __might_sleep+0x95/0x190 kernel/sched/core.c:6081 lock_sock_nested+0x37/0x110 net/core/sock.c:2772 lock_sock include/net/sock.h:1463 [inline] tipc_release+0x103/0xff0 net/tipc/socket.c:572 sock_release+0x8d/0x1e0 net/socket.c:594 tipc_topsrv_stop+0x3c0/0x610 net/tipc/topsrv.c:696 tipc_exit_net+0x15/0x40 net/tipc/core.c:96 ops_exit_list.isra.6+0xae/0x150 net/core/net_namespace.c:148 cleanup_net+0x6ba/0xd20 net/core/net_namespace.c:529 process_one_work+0xbbf/0x1af0 kernel/workqueue.c:2113 worker_thread+0x223/0x1990 kernel/workqueue.c:2247 kthread+0x33c/0x400 kernel/kthread.c:238 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:429 openvswitch: netlink: Flow actions attr not present in new flow. openvswitch: netlink: Flow actions attr not present in new flow. kauditd_printk_skb: 21 callbacks suppressed audit: type=1400 audit(1519070460.588:43): avc: denied { setopt } for pid=6369 comm="syz-executor0" scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tclass=netlink_crypto_socket permissive=1 audit: type=1400 audit(1519070460.787:44): avc: denied { getattr } for pid=6396 comm="syz-executor4" scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tclass=netlink_generic_socket permissive=1 audit: type=1400 audit(1519070460.837:45): avc: denied { getopt } for pid=6396 comm="syz-executor4" scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tclass=netlink_generic_socket permissive=1 audit: type=1400 audit(1519070460.838:46): avc: denied { setopt } for pid=6396 comm="syz-executor4" scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tclass=netlink_generic_socket permissive=1 sctp: [Deprecated]: syz-executor4 (pid 6447) Use of struct sctp_assoc_value in delayed_ack socket option. Use struct sctp_sack_info instead sctp: [Deprecated]: syz-executor4 (pid 6452) Use of struct sctp_assoc_value in delayed_ack socket option. Use struct sctp_sack_info instead TCP: request_sock_TCP: Possible SYN flooding on port 20022. Sending cookies. Check SNMP counters. netlink: 'syz-executor6': attribute type 2 has an invalid length. x_tables: ip6_tables: rpfilter match: used from hooks PREROUTING/OUTPUT, but only valid from PREROUTING kernel msg: ebtables bug: please report to author: counter_offset != totalcnt netlink: 'syz-executor6': attribute type 2 has an invalid length. kernel msg: ebtables bug: please report to author: counter_offset != totalcnt syz-executor5 (6470) used greatest stack depth: 14656 bytes left x_tables: ip6_tables: rpfilter match: used from hooks PREROUTING/OUTPUT, but only valid from PREROUTING ip6t_REJECT: TCP_RESET illegal for non-tcp ip6t_REJECT: TCP_RESET illegal for non-tcp Cannot find add_set index 0 as target Cannot find add_set index 0 as target xt_cgroup: no path or classid specified netlink: 4 bytes leftover after parsing attributes in process `syz-executor7'. audit: type=1400 audit(1519070461.790:47): avc: denied { setopt } for pid=6710 comm="syz-executor7" scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tclass=netlink_netfilter_socket permissive=1 xt_CT: You must specify a L4 protocol, and not use inversions on it. netlink: 4 bytes leftover after parsing attributes in process `syz-executor7'. audit: type=1400 audit(1519070461.895:48): avc: denied { prog_run } for pid=6749 comm="syz-executor2" scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tclass=bpf permissive=1 do_dccp_getsockopt: sockopt(PACKET_SIZE) is deprecated: fix your app netlink: 'syz-executor1': attribute type 1 has an invalid length. do_dccp_getsockopt: sockopt(PACKET_SIZE) is deprecated: fix your app xt_CT: netfilter: NOTRACK target is deprecated, use CT instead or upgrade iptables netlink: 'syz-executor1': attribute type 1 has an invalid length. audit: type=1400 audit(1519070462.091:49): avc: denied { connect } for pid=6816 comm="syz-executor1" scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tclass=netlink_netfilter_socket permissive=1 x_tables: ip6_tables: rpfilter match: used from hooks OUTPUT, but only valid from PREROUTING x_tables: ip6_tables: rpfilter match: used from hooks OUTPUT, but only valid from PREROUTING BUG: sleeping function called from invalid context at mm/slab.h:420 in_atomic(): 1, irqs_disabled(): 0, pid: 6923, name: syz-executor5 INFO: lockdep is turned off. CPU: 0 PID: 6923 Comm: syz-executor5 Tainted: G W 4.16.0-rc1+ #232 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0x194/0x257 lib/dump_stack.c:53 ___might_sleep+0x2b2/0x470 kernel/sched/core.c:6128 __might_sleep+0x95/0x190 kernel/sched/core.c:6081 slab_pre_alloc_hook mm/slab.h:420 [inline] slab_alloc mm/slab.c:3365 [inline] kmem_cache_alloc_trace+0x299/0x740 mm/slab.c:3605 kmalloc include/linux/slab.h:512 [inline] kzalloc include/linux/slab.h:701 [inline] rds_loop_conn_alloc+0xc8/0x380 net/rds/loop.c:126 __rds_conn_create+0x112f/0x1b50 net/rds/connection.c:227 device lo entered promiscuous mode rds_conn_create_outgoing+0x3f/0x50 net/rds/connection.c:309 rds_sendmsg+0xe63/0x2550 net/rds/send.c:1153 sock_sendmsg_nosec net/socket.c:629 [inline] sock_sendmsg+0xca/0x110 net/socket.c:639 SYSC_sendto+0x361/0x5c0 net/socket.c:1748 SyS_sendto+0x40/0x50 net/socket.c:1716 do_syscall_64+0x282/0x940 arch/x86/entry/common.c:287 entry_SYSCALL_64_after_hwframe+0x26/0x9b RIP: 0033:0x453d69 RSP: 002b:00007f355e6dfc68 EFLAGS: 00000246 ORIG_RAX: 000000000000002c RAX: ffffffffffffffda RBX: 00007f355e6e06d4 RCX: 0000000000453d69 RDX: 0000000000000001 RSI: 0000000020218000 RDI: 0000000000000013 RBP: 000000000072bea0 R08: 0000000020062000 R09: 0000000000000010 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 00000000000004b9 R14: 00000000006f71f8 R15: 0000000000000000 IPv6: NLM_F_REPLACE set, but no existing node found! IPv6: NLM_F_REPLACE set, but no existing node found! audit: type=1400 audit(1519070462.926:50): avc: denied { setopt } for pid=7007 comm="syz-executor7" scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=system_u:object_r:unlabeled_t:s0 tclass=socket permissive=1 audit: type=1400 audit(1519070463.073:51): avc: denied { ioctl } for pid=7061 comm="syz-executor2" path="socket:[18196]" dev="sockfs" ino=18196 ioctlcmd=0x3 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tclass=netlink_netfilter_socket permissive=1 x_tables: ip_tables: REDIRECT target: used from hooks INPUT, but only usable from PREROUTING/OUTPUT xt_recent: hitcount (65535) is larger than allowed maximum (255) netlink: 3 bytes leftover after parsing attributes in process `syz-executor0'. arp_tables: arptables: counters copy to user failed while replacing table xt_recent: hitcount (65535) is larger than allowed maximum (255) netlink: 3 bytes leftover after parsing attributes in process `syz-executor0'. xt_connbytes: Forcing CT accounting to be enabled Cannot find add_set index 31 as target sock: sock_set_timeout: `syz-executor4' (pid 7267) tries to set negative timeout Cannot find add_set index 31 as target audit: type=1400 audit(1519070463.762:52): avc: denied { create } for pid=7316 comm="syz-executor6" scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tclass=netlink_scsitransport_socket permissive=1 device lo entered promiscuous mode IPv6: ADDRCONF(NETDEV_CHANGE): vcan0: link becomes ready IPv6: ADDRCONF(NETDEV_CHANGE): vcan0: link becomes ready x_tables: ip_tables: rpfilter match: used from hooks PREROUTING/INPUT/FORWARD/OUTPUT, but only valid from PREROUTING bpf: check failed: parse error bpf: check failed: parse error xt_TCPMSS: Only works on TCP SYN packets xt_TCPMSS: Only works on TCP SYN packets netlink: 12 bytes leftover after parsing attributes in process `syz-executor1'. netlink: 12 bytes leftover after parsing attributes in process `syz-executor1'. TCP: request_sock_TCPv6: Possible SYN flooding on port 20030. Sending cookies. Check SNMP counters. xt_SECMARK: invalid security context 'system_u:object_r:udev_var_run_t' xt_SECMARK: invalid security context 'system_u:object_r:udev_var_run_t' l2tp_core: tunl 59: sockfd_lookup(fd=0) returned -88 l2tp_core: tunl 59: sockfd_lookup(fd=0) returned -88 netlink: 'syz-executor0': attribute type 15 has an invalid length. netlink: 'syz-executor0': attribute type 15 has an invalid length. Bearer <> rejected, not supported in standalone mode xt_CT: netfilter: NOTRACK target is deprecated, use CT instead or upgrade iptables kauditd_printk_skb: 3 callbacks suppressed audit: type=1400 audit(1519070465.705:56): avc: denied { read } for pid=8015 comm="syz-executor7" scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tclass=netlink_netfilter_socket permissive=1 netlink: 'syz-executor6': attribute type 39 has an invalid length. netlink: 'syz-executor6': attribute type 39 has an invalid length. netlink: 'syz-executor6': attribute type 39 has an invalid length. netlink: 'syz-executor6': attribute type 39 has an invalid length. netlink: 8 bytes leftover after parsing attributes in process `syz-executor7'. netlink: 8 bytes leftover after parsing attributes in process `syz-executor7'. xt_AUDIT: Audit type out of range (valid range: 0..2) xt_CT: You must specify a L4 protocol, and not use inversions on it. xt_AUDIT: Audit type out of range (valid range: 0..2)