[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 21.322734] random: sshd: uninitialized urandom read (32 bytes read, 31 bits of entropy available) [?25l[?1c7[ ok 8[?25h[?0c. [ 21.580561] random: sshd: uninitialized urandom read (32 bytes read, 32 bits of entropy available) [ 21.951831] random: sshd: uninitialized urandom read (32 bytes read, 33 bits of entropy available) Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 23.180734] random: sshd: uninitialized urandom read (32 bytes read, 124 bits of entropy available) [ 24.833033] random: nonblocking pool is initialized Warning: Permanently added '10.128.0.54' (ECDSA) to the list of known hosts. 2018/04/28 20:20:46 parsed 1 programs 2018/04/28 20:20:46 executed programs: 0 [ 46.223322] IPVS: Creating netns size=2552 id=1 [ 46.300868] IPVS: Creating netns size=2552 id=2 [ 46.373604] IPVS: Creating netns size=2552 id=3 [ 46.444393] IPVS: Creating netns size=2552 id=4 [ 46.502761] IPVS: Creating netns size=2552 id=5 [ 46.578035] IPVS: Creating netns size=2552 id=6 [ 46.702365] IPVS: Creating netns size=2552 id=7 [ 46.806428] IPVS: Creating netns size=2552 id=8 [ 46.827986] IPv6: ADDRCONF(NETDEV_UP): veth0_to_bridge: link is not ready [ 46.909159] IPv6: ADDRCONF(NETDEV_UP): veth1_to_bridge: link is not ready [ 47.204625] IPv6: ADDRCONF(NETDEV_UP): veth0_to_bridge: link is not ready [ 47.216933] IPv6: ADDRCONF(NETDEV_UP): veth0_to_bridge: link is not ready [ 47.253096] IPv6: ADDRCONF(NETDEV_UP): veth0_to_bond: link is not ready [ 47.261752] IPv6: ADDRCONF(NETDEV_UP): veth1_to_bridge: link is not ready [ 47.269572] IPv6: ADDRCONF(NETDEV_UP): veth1_to_bridge: link is not ready [ 47.370308] IPv6: ADDRCONF(NETDEV_UP): veth0_to_bridge: link is not ready [ 47.377586] IPv6: ADDRCONF(NETDEV_UP): veth1_to_bond: link is not ready [ 47.426376] IPv6: ADDRCONF(NETDEV_UP): veth1_to_bridge: link is not ready [ 47.573638] IPv6: ADDRCONF(NETDEV_UP): veth0_to_bond: link is not ready [ 47.603395] IPv6: ADDRCONF(NETDEV_UP): veth0_to_bond: link is not ready [ 47.630224] IPv6: ADDRCONF(NETDEV_UP): veth1_to_bond: link is not ready [ 47.647597] IPv6: ADDRCONF(NETDEV_UP): veth1_to_bond: link is not ready [ 47.715137] IPv6: ADDRCONF(NETDEV_UP): veth0_to_team: link is not ready [ 47.724701] IPv6: ADDRCONF(NETDEV_UP): veth0_to_bridge: link is not ready [ 47.751375] IPv6: ADDRCONF(NETDEV_UP): veth0_to_bond: link is not ready [ 47.795532] IPv6: ADDRCONF(NETDEV_UP): veth1_to_bridge: link is not ready [ 47.837356] IPv6: ADDRCONF(NETDEV_UP): veth1_to_team: link is not ready [ 47.863742] IPv6: ADDRCONF(NETDEV_UP): veth0_to_bridge: link is not ready [ 47.891579] IPv6: ADDRCONF(NETDEV_CHANGE): veth0_to_bridge: link becomes ready [ 47.902105] IPv6: ADDRCONF(NETDEV_UP): veth1_to_bond: link is not ready [ 47.949076] IPv6: ADDRCONF(NETDEV_UP): veth0_to_team: link is not ready [ 47.978577] IPv6: ADDRCONF(NETDEV_CHANGE): veth1_to_bridge: link becomes ready [ 47.989019] IPv6: ADDRCONF(NETDEV_UP): veth0_to_team: link is not ready [ 47.996630] IPv6: ADDRCONF(NETDEV_UP): veth1_to_bridge: link is not ready [ 48.006131] IPv6: ADDRCONF(NETDEV_UP): veth1_to_team: link is not ready [ 48.038206] IPv6: ADDRCONF(NETDEV_UP): veth1_to_team: link is not ready [ 48.075834] IPv6: ADDRCONF(NETDEV_UP): veth0_to_bridge: link is not ready [ 48.090762] IPv6: ADDRCONF(NETDEV_CHANGE): veth0_to_bridge: link becomes ready [ 48.099139] IPv6: ADDRCONF(NETDEV_CHANGE): veth0_to_bridge: link becomes ready [ 48.113735] IPv6: ADDRCONF(NETDEV_UP): veth0_to_bridge: link is not ready [ 48.143520] IPv6: ADDRCONF(NETDEV_UP): veth1_to_bridge: link is not ready [ 48.153741] IPv6: ADDRCONF(NETDEV_UP): veth0_to_bond: link is not ready [ 48.180634] IPv6: ADDRCONF(NETDEV_CHANGE): veth1_to_bridge: link becomes ready [ 48.188455] IPv6: ADDRCONF(NETDEV_CHANGE): veth1_to_bridge: link becomes ready [ 48.201317] IPv6: ADDRCONF(NETDEV_UP): veth1_to_bond: link is not ready [ 48.249817] IPv6: ADDRCONF(NETDEV_UP): veth1_to_bridge: link is not ready [ 48.369164] IPv6: ADDRCONF(NETDEV_UP): veth0_to_bond: link is not ready [ 48.379030] IPv6: ADDRCONF(NETDEV_UP): veth0_to_team: link is not ready [ 48.466809] IPv6: ADDRCONF(NETDEV_UP): veth1_to_bond: link is not ready [ 48.478467] IPv6: ADDRCONF(NETDEV_UP): veth1_to_team: link is not ready [ 48.514312] IPv6: ADDRCONF(NETDEV_UP): veth0_to_bond: link is not ready [ 48.609101] IPv6: ADDRCONF(NETDEV_UP): veth1_to_bond: link is not ready [ 48.625218] IPv6: ADDRCONF(NETDEV_UP): veth0_to_bond: link is not ready [ 48.637435] IPv6: ADDRCONF(NETDEV_CHANGE): veth0_to_bridge: link becomes ready [ 48.653905] IPv6: ADDRCONF(NETDEV_UP): veth0_to_team: link is not ready [ 48.669083] IPv6: ADDRCONF(NETDEV_CHANGE): veth1_to_bridge: link becomes ready [ 48.738686] IPv6: ADDRCONF(NETDEV_UP): veth1_to_team: link is not ready [ 48.752699] IPv6: ADDRCONF(NETDEV_UP): veth1_to_bond: link is not ready [ 48.832299] IPv6: ADDRCONF(NETDEV_CHANGE): veth0_to_bridge: link becomes ready [ 48.897988] IPv6: ADDRCONF(NETDEV_UP): veth0_to_team: link is not ready [ 48.922417] IPv6: ADDRCONF(NETDEV_CHANGE): veth1_to_bridge: link becomes ready [ 48.989019] IPv6: ADDRCONF(NETDEV_UP): veth1_to_team: link is not ready [ 49.031233] IPv6: ADDRCONF(NETDEV_UP): veth0_to_team: link is not ready [ 49.053622] IPv6: ADDRCONF(NETDEV_CHANGE): veth0_to_bridge: link becomes ready [ 49.078973] IPv6: ADDRCONF(NETDEV_UP): veth1_to_team: link is not ready [ 49.114181] IPv6: ADDRCONF(NETDEV_UP): veth0_to_team: link is not ready [ 49.147877] IPv6: ADDRCONF(NETDEV_CHANGE): veth0_to_bridge: link becomes ready [ 49.172069] IPv6: ADDRCONF(NETDEV_UP): veth1_to_team: link is not ready [ 49.197766] IPv6: ADDRCONF(NETDEV_CHANGE): veth1_to_bridge: link becomes ready [ 49.229274] IPv6: ADDRCONF(NETDEV_CHANGE): veth1_to_bridge: link becomes ready [ 49.249729] IPv6: ADDRCONF(NETDEV_CHANGE): veth0_to_bridge: link becomes ready [ 49.284912] IPv6: ADDRCONF(NETDEV_CHANGE): veth1_to_bridge: link becomes ready [ 51.833133] IPv6: ADDRCONF(NETDEV_UP): veth0: link is not ready [ 51.914858] IPv6: ADDRCONF(NETDEV_UP): veth0: link is not ready [ 51.982470] IPv6: ADDRCONF(NETDEV_UP): veth0: link is not ready [ 52.061726] IPv6: ADDRCONF(NETDEV_CHANGE): veth0: link becomes ready [ 52.169761] IPv6: ADDRCONF(NETDEV_CHANGE): veth0: link becomes ready [ 52.199066] IPv6: ADDRCONF(NETDEV_CHANGE): veth0: link becomes ready [ 52.337157] IPv6: ADDRCONF(NETDEV_UP): veth0: link is not ready [ 52.468874] IPv6: ADDRCONF(NETDEV_UP): veth0: link is not ready [ 52.550462] IPv6: ADDRCONF(NETDEV_CHANGE): veth0: link becomes ready [ 52.679801] IPv6: ADDRCONF(NETDEV_UP): veth0: link is not ready [ 52.699391] IPv6: ADDRCONF(NETDEV_CHANGE): veth0: link becomes ready [ 52.817203] IPv6: ADDRCONF(NETDEV_UP): veth0: link is not ready [ 52.903135] IPv6: ADDRCONF(NETDEV_CHANGE): veth0: link becomes ready [ 52.925950] IPv6: ADDRCONF(NETDEV_UP): veth0: link is not ready [ 53.096465] IPv6: ADDRCONF(NETDEV_CHANGE): veth0: link becomes ready [ 53.245541] IPv6: ADDRCONF(NETDEV_CHANGE): veth0: link becomes ready [ 53.887154] [ 53.888840] ====================================================== [ 53.895150] [ INFO: possible circular locking dependency detected ] [ 53.901546] 4.4.129-g23eaecc #26 Not tainted [ 53.905942] ------------------------------------------------------- [ 53.912344] syz-executor0/5753 is trying to acquire lock: [ 53.917871] (&(&q->lock)->rlock){+.-...}, at: [] ip_defrag+0x318/0x3fe0 [ 53.926801] [ 53.926801] but task is already holding lock: [ 53.932764] (_xmit_NETROM){+.-...}, at: [] sch_direct_xmit+0x23c/0x6e0 [ 53.941604] [ 53.941604] which lock already depends on the new lock. [ 53.941604] [ 53.949912] [ 53.949912] the existing dependency chain (in reverse order) is: [ 53.957523] -> #1 (_xmit_NETROM){+.-...}: [ 53.962352] [] lock_acquire+0x15e/0x450 [ 53.968623] [] _raw_spin_lock_irqsave+0x4e/0x70 [ 53.975592] [] depot_save_stack+0x211/0x610 [ 53.982219] [] save_stack+0xa9/0xd0 [ 53.988142] [] kasan_kmalloc+0xc7/0xe0 [ 53.994331] [] kasan_slab_alloc+0x12/0x20 [ 54.000780] [] kmem_cache_alloc+0xbe/0x2a0 [ 54.007320] [] inet_getpeer.part.5+0xeac/0x15a0 [ 54.014282] [] inet_getpeer+0x55b/0x6f0 [ 54.020565] [] icmp6_send+0x17c5/0x1b80 [ 54.026837] [] icmpv6_param_prob+0x29/0x40 [ 54.033375] [] ipv6_frag_rcv+0x3f94/0x4fd0 [ 54.039913] [] ip6_input_finish+0x32e/0x1550 [ 54.046628] [] ip6_input+0xf6/0x200 [ 54.052552] [] ip6_rcv_finish+0x13d/0x640 [ 54.059004] [] ipv6_rcv+0x10cb/0x1cd0 [ 54.065103] [] __netif_receive_skb_core+0x12d6/0x2940 [ 54.072593] [] __netif_receive_skb+0x5b/0x1b0 [ 54.079393] [] process_backlog+0x216/0x6a0 [ 54.085933] [] net_rx_action+0x3a2/0xdb0 [ 54.092290] [] __do_softirq+0x22c/0xa1a [ 54.098563] [] do_softirq_own_stack+0x1c/0x30 [ 54.105380] [] do_softirq.part.16+0x54/0x60 [ 54.112008] [] do_softirq+0x19/0x20 [ 54.117931] [] netif_rx_ni+0xec/0x3a0 [ 54.124031] [] tun_get_user+0xbe7/0x2410 [ 54.130390] [] tun_chr_write_iter+0xd5/0x190 [ 54.137098] [] do_iter_readv_writev+0x13c/0x1e0 [ 54.144065] [] compat_do_readv_writev+0x2e2/0x6e0 [ 54.151203] [] compat_writev+0xe1/0x150 [ 54.157474] [] compat_SyS_writev+0xd8/0x1c0 [ 54.164092] [] do_fast_syscall_32+0x326/0x8b0 [ 54.170880] [] sysenter_flags_fixed+0xd/0x17 [ 54.177589] -> #0 (&(&q->lock)->rlock){+.-...}: [ 54.182938] [] __lock_acquire+0x3902/0x5270 [ 54.189551] [] lock_acquire+0x15e/0x450 [ 54.195826] [] _raw_spin_lock+0x36/0x50 [ 54.202102] [] ip_defrag+0x318/0x3fe0 [ 54.208199] [] ip_check_defrag+0x3c8/0x7e0 [ 54.214736] [] packet_rcv_fanout+0x52a/0x5e0 [ 54.221444] [] dev_hard_start_xmit+0x644/0x11c0 [ 54.228415] [] sch_direct_xmit+0x2c1/0x6e0 [ 54.234947] [] __dev_queue_xmit+0xef3/0x1c80 [ 54.241654] [] dev_queue_xmit+0x17/0x20 [ 54.247933] [] neigh_resolve_output+0x637/0x790 [ 54.254897] [] ip_finish_output2+0x6ab/0x1110 [ 54.261690] [] ip_do_fragment+0x198b/0x2150 [ 54.268314] [] ip_fragment.constprop.50+0x143/0x200 [ 54.275634] [] ip_finish_output+0x6c4/0xbc0 [ 54.282255] [] ip_mc_output+0x233/0x980 [ 54.288539] [] ip_local_out+0x9b/0x180 [ 54.294738] [] ip_send_skb+0x3c/0xc0 [ 54.300750] [] udp_send_skb+0x5c3/0xc60 [ 54.307023] [] udp_sendmsg+0x16ce/0x1bb0 [ 54.313385] [] inet_sendmsg+0x203/0x4d0 [ 54.319680] [] sock_sendmsg+0xcc/0x110 [ 54.325870] [] SYSC_sendto+0x21c/0x370 [ 54.332057] [] SyS_sendto+0x40/0x50 [ 54.338013] [] do_fast_syscall_32+0x326/0x8b0 [ 54.344809] [] sysenter_flags_fixed+0xd/0x17 [ 54.351522] [ 54.351522] other info that might help us debug this: [ 54.351522] [ 54.359660] Possible unsafe locking scenario: [ 54.359660] [ 54.365709] CPU0 CPU1 [ 54.370365] ---- ---- [ 54.375024] lock(_xmit_NETROM); [ 54.378718] lock(&(&q->lock)->rlock); [ 54.385465] lock(_xmit_NETROM); [ 54.391677] lock(&(&q->lock)->rlock); [ 54.395893] [ 54.395893] *** DEADLOCK *** [ 54.395893] [ 54.401943] 4 locks held by syz-executor0/5753: [ 54.406598] #0: (rcu_read_lock_bh){......}, at: [] ip_finish_output2+0x212/0x1110 [ 54.416629] #1: (rcu_read_lock_bh){......}, at: [] __dev_queue_xmit+0x1d7/0x1c80 [ 54.426549] #2: (_xmit_NETROM){+.-...}, at: [] sch_direct_xmit+0x23c/0x6e0 [ 54.435957] #3: (rcu_read_lock){......}, at: [] dev_hard_start_xmit+0xa8/0x11c0 [ 54.445790] [ 54.445790] stack backtrace: [ 54.450300] CPU: 0 PID: 5753 Comm: syz-executor0 Not tainted 4.4.129-g23eaecc #26 [ 54.457909] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 54.467261] 0000000000000000 d7667c0e8d681299 ffff8800bac46cc8 ffffffff81e0dc8d [ 54.475320] ffffffff853ee300 ffffffff853ec650 ffffffff853ee300 ffff8800b210b950 [ 54.483367] ffff8800b210b000 ffff8800bac46d10 ffffffff8140e3fb 0000000000000003 [ 54.491422] Call Trace: [ 54.494001] [] dump_stack+0xc1/0x124 [ 54.499366] [] print_circular_bug.cold.50+0x1bd/0x27d [ 54.506200] [] __lock_acquire+0x3902/0x5270 [ 54.512152] [] ? debug_check_no_locks_freed+0x210/0x210 [ 54.519140] [] ? trace_hardirqs_on_caller+0x266/0x590 [ 54.525954] [] lock_acquire+0x15e/0x450 [ 54.531551] [] ? ip_defrag+0x318/0x3fe0 [ 54.537152] [] ? inet_frag_find+0x22e/0x9c0 [ 54.543099] [] _raw_spin_lock+0x36/0x50 [ 54.548693] [] ? ip_defrag+0x318/0x3fe0 [ 54.554290] [] ip_defrag+0x318/0x3fe0 [ 54.559714] [] ? debug_check_no_locks_freed+0x210/0x210 [ 54.566699] [] ? memcpy+0x45/0x50 [ 54.571778] [] ? ip_expire+0x770/0x770 [ 54.577297] [] ip_check_defrag+0x3c8/0x7e0 [ 54.583153] [] ? ip_defrag+0x3fe0/0x3fe0 [ 54.588838] [] packet_rcv_fanout+0x52a/0x5e0 [ 54.594867] [] ? packet_bind+0x1a0/0x1a0 [ 54.600552] [] dev_hard_start_xmit+0x644/0x11c0 [ 54.606842] [] ? dev_hard_start_xmit+0xa8/0x11c0 [ 54.613222] [] sch_direct_xmit+0x2c1/0x6e0 [ 54.619078] [] ? dev_watchdog+0x7f0/0x7f0 [ 54.624847] [] __dev_queue_xmit+0xef3/0x1c80 [ 54.630878] [] ? __dev_queue_xmit+0x1d7/0x1c80 [ 54.637086] [] ? debug_check_no_locks_freed+0x210/0x210 [ 54.644070] [] ? netdev_pick_tx+0x2c0/0x2c0 [ 54.650019] [] ? memcpy+0x45/0x50 [ 54.655102] [] dev_queue_xmit+0x17/0x20 [ 54.660696] [] neigh_resolve_output+0x637/0x790 [ 54.666988] [] ? ip_finish_output2+0x6ab/0x1110 [ 54.673280] [] ip_finish_output2+0x6ab/0x1110 [ 54.679397] [] ? ip_finish_output2+0x212/0x1110 [ 54.685688] [] ? nf_ct_deliver_cached_events+0x335/0x560 [ 54.692759] [] ? nf_ct_deliver_cached_events+0x83/0x560 [ 54.699744] [] ? ip_copy_metadata+0x700/0x700 [ 54.705862] [] ? ip_options_fragment+0x1ac/0x280 [ 54.712239] [] ip_do_fragment+0x198b/0x2150 [ 54.718196] [] ? ip_copy_metadata+0x700/0x700 [ 54.724317] [] ip_fragment.constprop.50+0x143/0x200 [ 54.730954] [] ip_finish_output+0x6c4/0xbc0 [ 54.736898] [] ip_mc_output+0x233/0x980 [ 54.742498] [] ? ip_queue_xmit+0x1ab0/0x1ab0 [ 54.748531] [] ? ip_make_skb+0x116/0x210 [ 54.754214] [] ? ip_fragment.constprop.50+0x200/0x200 [ 54.761025] [] ? ip_flush_pending_frames+0x30/0x30 [ 54.767577] [] ip_local_out+0x9b/0x180 [ 54.773086] [] ip_send_skb+0x3c/0xc0 [ 54.778426] [] udp_send_skb+0x5c3/0xc60 [ 54.784023] [] udp_sendmsg+0x16ce/0x1bb0 [ 54.789712] [] ? ip_reply_glue_bits+0xc0/0xc0 [ 54.795827] [] ? udp4_lib_lookup+0x60/0x60 [ 54.801683] [] ? debug_check_no_locks_freed+0x210/0x210 [ 54.808670] [] ? sock_has_perm+0x1c1/0x400 [ 54.814528] [] ? sock_has_perm+0x29f/0x400 [ 54.820388] [] ? sock_has_perm+0x9f/0x400 [ 54.826171] [] ? inet_sendmsg+0x143/0x4d0 [ 54.831940] [] inet_sendmsg+0x203/0x4d0 [ 54.837540] [] ? inet_sendmsg+0x73/0x4d0 [ 54.843224] [] ? inet_recvmsg+0x4c0/0x4c0 [ 54.848992] [] sock_sendmsg+0xcc/0x110 [ 54.854501] [] SYSC_sendto+0x21c/0x370 [ 54.860010] [] ? SYSC_connect+0x300/0x300 [ 54.865788] [] ? ip4_datagram_connect+0x3a/0x50 [ 54.872080] [] ? inet_dgram_connect+0x11e/0x200 [ 54.878370] [] ? SYSC_connect+0x22a/0x300 [ 54.884142] [] ? compat_SyS_futex+0x1e1/0x2f0 2018/04/28 20:20:55 executed programs: 8 [ 54.890262] [] ? fd_install+0x4d/0x60 [ 54.895685] [] ? compat_SyS_get_robust_list+0x310/0x310 [ 54.902669] [] ? SyS_socket+0x121/0x1b0 [ 54.908265] [] ? move_addr_to_kernel+0x50/0x50 [ 54.914467] [] SyS_sendto+0x40/0x50 [ 54.919716] [] ? SyS_getpeername+0x30/0x30 [ 54.925571] [] do_fast_syscall_32+0x326/0x8b0 [ 54.931689] [] sysenter_flags_fixed+0xd/0x17 2018/04/28 20:21:00 executed programs: 215