[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 21.894031] random: sshd: uninitialized urandom read (32 bytes read, 35 bits of entropy available) [?25l[?1c7[ ok 8[?25h[?0c. [ 22.361980] random: sshd: uninitialized urandom read (32 bytes read, 35 bits of entropy available) [ 22.726813] random: sshd: uninitialized urandom read (32 bytes read, 37 bits of entropy available) Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 23.928049] random: sshd: uninitialized urandom read (32 bytes read, 118 bits of entropy available) [ 24.091220] random: sshd: uninitialized urandom read (32 bytes read, 121 bits of entropy available) Warning: Permanently added '10.128.10.19' (ECDSA) to the list of known hosts. [ 29.545299] random: sshd: uninitialized urandom read (32 bytes read, 125 bits of entropy available) 2018/04/28 21:03:15 parsed 1 programs 2018/04/28 21:03:15 executed programs: 0 [ 30.033184] IPVS: Creating netns size=2552 id=1 [ 30.126407] IPVS: Creating netns size=2552 id=2 [ 30.186629] IPVS: Creating netns size=2552 id=3 [ 30.290756] IPVS: Creating netns size=2552 id=4 [ 30.372733] IPVS: Creating netns size=2552 id=5 [ 30.513288] IPVS: Creating netns size=2552 id=6 [ 30.753734] IPVS: Creating netns size=2552 id=7 [ 30.882983] IPv6: ADDRCONF(NETDEV_UP): veth0_to_bridge: link is not ready [ 30.934298] IPv6: ADDRCONF(NETDEV_UP): veth1_to_bridge: link is not ready [ 30.976352] IPVS: Creating netns size=2552 id=8 [ 30.986403] IPv6: ADDRCONF(NETDEV_UP): veth0_to_bridge: link is not ready [ 31.064556] IPv6: ADDRCONF(NETDEV_UP): veth1_to_bridge: link is not ready [ 31.377633] IPv6: ADDRCONF(NETDEV_UP): veth0_to_bond: link is not ready [ 31.387735] IPv6: ADDRCONF(NETDEV_UP): veth0_to_bridge: link is not ready [ 31.461495] IPv6: ADDRCONF(NETDEV_UP): veth0_to_bond: link is not ready [ 31.472264] IPv6: ADDRCONF(NETDEV_UP): veth1_to_bond: link is not ready [ 31.481737] IPv6: ADDRCONF(NETDEV_UP): veth1_to_bridge: link is not ready [ 31.536821] IPv6: ADDRCONF(NETDEV_UP): veth1_to_bond: link is not ready [ 31.813032] IPv6: ADDRCONF(NETDEV_UP): veth0_to_bridge: link is not ready [ 31.865229] IPv6: ADDRCONF(NETDEV_UP): veth0_to_team: link is not ready [ 31.884084] IPv6: ADDRCONF(NETDEV_UP): veth1_to_bridge: link is not ready [ 31.958906] IPv6: ADDRCONF(NETDEV_UP): veth1_to_team: link is not ready [ 31.992348] IPv6: ADDRCONF(NETDEV_UP): veth0_to_team: link is not ready [ 32.032976] IPv6: ADDRCONF(NETDEV_CHANGE): veth0_to_bridge: link becomes ready [ 32.045078] IPv6: ADDRCONF(NETDEV_UP): veth0_to_bond: link is not ready [ 32.060093] IPv6: ADDRCONF(NETDEV_UP): veth1_to_team: link is not ready [ 32.125450] IPv6: ADDRCONF(NETDEV_UP): veth0_to_bridge: link is not ready [ 32.155163] IPv6: ADDRCONF(NETDEV_UP): veth0_to_bridge: link is not ready [ 32.173707] IPv6: ADDRCONF(NETDEV_CHANGE): veth1_to_bridge: link becomes ready [ 32.199613] IPv6: ADDRCONF(NETDEV_UP): veth1_to_bond: link is not ready [ 32.207770] IPv6: ADDRCONF(NETDEV_UP): veth1_to_bridge: link is not ready [ 32.225866] IPv6: ADDRCONF(NETDEV_CHANGE): veth0_to_bridge: link becomes ready [ 32.236261] IPv6: ADDRCONF(NETDEV_UP): veth1_to_bridge: link is not ready [ 32.245507] IPv6: ADDRCONF(NETDEV_UP): veth0_to_bond: link is not ready [ 32.295007] IPv6: ADDRCONF(NETDEV_CHANGE): veth1_to_bridge: link becomes ready [ 32.358492] IPv6: ADDRCONF(NETDEV_UP): veth1_to_bond: link is not ready [ 32.594098] IPv6: ADDRCONF(NETDEV_UP): veth0_to_bond: link is not ready [ 32.644111] IPv6: ADDRCONF(NETDEV_UP): veth0_to_bond: link is not ready [ 32.674428] IPv6: ADDRCONF(NETDEV_UP): veth1_to_bond: link is not ready [ 32.693438] IPv6: ADDRCONF(NETDEV_UP): veth0_to_team: link is not ready [ 32.705732] IPv6: ADDRCONF(NETDEV_UP): veth1_to_bond: link is not ready [ 32.719799] IPv6: ADDRCONF(NETDEV_UP): veth0_to_team: link is not ready [ 32.739213] IPv6: ADDRCONF(NETDEV_UP): veth0_to_bridge: link is not ready [ 32.807763] IPv6: ADDRCONF(NETDEV_UP): veth1_to_team: link is not ready [ 32.841065] IPv6: ADDRCONF(NETDEV_UP): veth1_to_team: link is not ready [ 32.880117] IPv6: ADDRCONF(NETDEV_UP): veth1_to_bridge: link is not ready [ 32.893579] IPv6: ADDRCONF(NETDEV_CHANGE): veth0_to_bridge: link becomes ready [ 32.996044] IPv6: ADDRCONF(NETDEV_CHANGE): veth0_to_bridge: link becomes ready [ 33.004982] IPv6: ADDRCONF(NETDEV_CHANGE): veth1_to_bridge: link becomes ready [ 33.081690] IPv6: ADDRCONF(NETDEV_CHANGE): veth1_to_bridge: link becomes ready [ 33.151748] IPv6: ADDRCONF(NETDEV_UP): veth0_to_team: link is not ready [ 33.172186] IPv6: ADDRCONF(NETDEV_UP): veth0_to_team: link is not ready [ 33.203926] IPv6: ADDRCONF(NETDEV_UP): veth0_to_bond: link is not ready [ 33.222956] IPv6: ADDRCONF(NETDEV_UP): veth0_to_bridge: link is not ready [ 33.232273] IPv6: ADDRCONF(NETDEV_UP): veth1_to_team: link is not ready [ 33.241678] IPv6: ADDRCONF(NETDEV_UP): veth1_to_team: link is not ready [ 33.274357] IPv6: ADDRCONF(NETDEV_UP): veth1_to_bridge: link is not ready [ 33.302821] IPv6: ADDRCONF(NETDEV_UP): veth1_to_bond: link is not ready [ 33.316115] IPv6: ADDRCONF(NETDEV_CHANGE): veth0_to_bridge: link becomes ready [ 33.361707] IPv6: ADDRCONF(NETDEV_CHANGE): veth0_to_bridge: link becomes ready [ 33.410192] IPv6: ADDRCONF(NETDEV_CHANGE): veth1_to_bridge: link becomes ready [ 33.419860] IPv6: ADDRCONF(NETDEV_CHANGE): veth1_to_bridge: link becomes ready [ 33.643349] IPv6: ADDRCONF(NETDEV_UP): veth0_to_bond: link is not ready [ 33.679443] IPv6: ADDRCONF(NETDEV_UP): veth0_to_team: link is not ready [ 33.710760] IPv6: ADDRCONF(NETDEV_UP): veth1_to_bond: link is not ready [ 33.731038] IPv6: ADDRCONF(NETDEV_UP): veth1_to_team: link is not ready [ 33.842679] IPv6: ADDRCONF(NETDEV_CHANGE): veth0_to_bridge: link becomes ready [ 33.927147] IPv6: ADDRCONF(NETDEV_CHANGE): veth1_to_bridge: link becomes ready [ 34.085877] IPv6: ADDRCONF(NETDEV_UP): veth0_to_team: link is not ready [ 34.147467] IPv6: ADDRCONF(NETDEV_UP): veth1_to_team: link is not ready [ 34.240903] IPv6: ADDRCONF(NETDEV_CHANGE): veth0_to_bridge: link becomes ready [ 34.278734] IPv6: ADDRCONF(NETDEV_CHANGE): veth1_to_bridge: link becomes ready [ 36.126223] IPv6: ADDRCONF(NETDEV_UP): veth0: link is not ready [ 36.216009] IPv6: ADDRCONF(NETDEV_UP): veth0: link is not ready [ 36.373672] IPv6: ADDRCONF(NETDEV_CHANGE): veth0: link becomes ready [ 36.407637] IPv6: ADDRCONF(NETDEV_UP): veth0: link is not ready [ 36.477564] IPv6: ADDRCONF(NETDEV_CHANGE): veth0: link becomes ready [ 36.552419] IPv6: ADDRCONF(NETDEV_UP): veth0: link is not ready [ 36.653791] IPv6: ADDRCONF(NETDEV_CHANGE): veth0: link becomes ready [ 36.782350] IPv6: ADDRCONF(NETDEV_CHANGE): veth0: link becomes ready [ 36.926116] IPv6: ADDRCONF(NETDEV_UP): veth0: link is not ready [ 36.956036] IPv6: ADDRCONF(NETDEV_UP): veth0: link is not ready [ 37.195433] IPv6: ADDRCONF(NETDEV_UP): veth0: link is not ready [ 37.220466] IPv6: ADDRCONF(NETDEV_CHANGE): veth0: link becomes ready [ 37.227612] IPv6: ADDRCONF(NETDEV_CHANGE): veth0: link becomes ready [ 37.450126] IPv6: ADDRCONF(NETDEV_CHANGE): veth0: link becomes ready [ 37.802188] IPv6: ADDRCONF(NETDEV_UP): veth0: link is not ready [ 38.025659] [ 38.027328] ====================================================== [ 38.033633] [ INFO: possible circular locking dependency detected ] [ 38.040134] 4.4.129-g23eaecc #26 Not tainted [ 38.044530] ------------------------------------------------------- [ 38.050946] syz-executor1/5772 is trying to acquire lock: [ 38.056471] (&(&q->lock)->rlock){+.-...}, at: [] ip_defrag+0x318/0x3fe0 [ 38.065412] [ 38.065412] but task is already holding lock: [ 38.071375] (_xmit_NETROM){+.-...}, at: [] sch_direct_xmit+0x23c/0x6e0 [ 38.080219] [ 38.080219] which lock already depends on the new lock. [ 38.080219] [ 38.088868] [ 38.088868] the existing dependency chain (in reverse order) is: [ 38.096472] -> #1 (_xmit_NETROM){+.-...}: [ 38.101293] [] lock_acquire+0x15e/0x450 [ 38.107587] [] _raw_spin_lock_irqsave+0x4e/0x70 [ 38.114540] [] depot_save_stack+0x211/0x610 [ 38.121138] [] save_stack+0xa9/0xd0 [ 38.127033] [] kasan_kmalloc+0xc7/0xe0 [ 38.133193] [] kasan_slab_alloc+0x12/0x20 [ 38.139612] [] kmem_cache_alloc+0xbe/0x2a0 [ 38.146118] [] inet_getpeer.part.5+0xeac/0x15a0 [ 38.153060] [] inet_getpeer+0x55b/0x6f0 [ 38.159309] [] icmp6_send+0x17c5/0x1b80 [ 38.165562] [] icmpv6_param_prob+0x29/0x40 [ 38.172345] [] ipv6_frag_rcv+0x3f94/0x4fd0 [ 38.178857] [] ip6_input_finish+0x32e/0x1550 [ 38.185540] [] ip6_input+0xf6/0x200 [ 38.191434] [] ip6_rcv_finish+0x13d/0x640 [ 38.197871] [] ipv6_rcv+0x10cb/0x1cd0 [ 38.203956] [] __netif_receive_skb_core+0x12d6/0x2940 [ 38.211415] [] __netif_receive_skb+0x5b/0x1b0 [ 38.218182] [] process_backlog+0x216/0x6a0 [ 38.224684] [] net_rx_action+0x3a2/0xdb0 [ 38.231021] [] __do_softirq+0x22c/0xa1a [ 38.237257] [] do_softirq_own_stack+0x1c/0x30 [ 38.244016] [] do_softirq.part.16+0x54/0x60 [ 38.250609] [] do_softirq+0x19/0x20 [ 38.256511] [] netif_rx_ni+0xec/0x3a0 [ 38.262579] [] tun_get_user+0xbe7/0x2410 [ 38.268906] [] tun_chr_write_iter+0xd5/0x190 [ 38.275580] [] do_iter_readv_writev+0x13c/0x1e0 [ 38.282517] [] compat_do_readv_writev+0x2e2/0x6e0 [ 38.289634] [] compat_writev+0xe1/0x150 [ 38.295881] [] compat_SyS_writev+0xd8/0x1c0 [ 38.302479] [] do_fast_syscall_32+0x326/0x8b0 [ 38.309244] [] sysenter_flags_fixed+0xd/0x17 [ 38.315964] -> #0 (&(&q->lock)->rlock){+.-...}: [ 38.321353] [] __lock_acquire+0x3902/0x5270 [ 38.327942] [] lock_acquire+0x15e/0x450 [ 38.334188] [] _raw_spin_lock+0x36/0x50 [ 38.340439] [] ip_defrag+0x318/0x3fe0 [ 38.346528] [] ip_check_defrag+0x3c8/0x7e0 [ 38.353051] [] packet_rcv_fanout+0x52a/0x5e0 [ 38.359744] [] dev_hard_start_xmit+0x644/0x11c0 [ 38.366798] [] sch_direct_xmit+0x2c1/0x6e0 [ 38.373304] [] __dev_queue_xmit+0xef3/0x1c80 [ 38.379974] [] dev_queue_xmit+0x17/0x20 [ 38.386210] [] neigh_resolve_output+0x637/0x790 [ 38.393146] [] ip_finish_output2+0x6ab/0x1110 [ 38.399919] [] ip_do_fragment+0x198b/0x2150 [ 38.406510] [] ip_fragment.constprop.50+0x143/0x200 [ 38.413797] [] ip_finish_output+0x6c4/0xbc0 [ 38.420416] [] ip_mc_output+0x233/0x980 [ 38.426672] [] ip_local_out+0x9b/0x180 [ 38.432841] [] ip_send_skb+0x3c/0xc0 [ 38.438913] [] udp_send_skb+0x5c3/0xc60 [ 38.445161] [] udp_sendmsg+0x16ce/0x1bb0 [ 38.451490] [] inet_sendmsg+0x203/0x4d0 [ 38.457740] [] sock_sendmsg+0xcc/0x110 [ 38.463923] [] SYSC_sendto+0x21c/0x370 [ 38.470080] [] SyS_sendto+0x40/0x50 [ 38.475982] [] do_fast_syscall_32+0x326/0x8b0 [ 38.482753] [] sysenter_flags_fixed+0xd/0x17 [ 38.489450] [ 38.489450] other info that might help us debug this: [ 38.489450] [ 38.497580] Possible unsafe locking scenario: [ 38.497580] [ 38.503623] CPU0 CPU1 [ 38.508275] ---- ---- [ 38.512914] lock(_xmit_NETROM); [ 38.516578] lock(&(&q->lock)->rlock); [ 38.523296] lock(_xmit_NETROM); [ 38.529506] lock(&(&q->lock)->rlock); [ 38.533707] [ 38.533707] *** DEADLOCK *** [ 38.533707] [ 38.539748] 4 locks held by syz-executor1/5772: [ 38.544394] #0: (rcu_read_lock_bh){......}, at: [] ip_finish_output2+0x212/0x1110 [ 38.554373] #1: (rcu_read_lock_bh){......}, at: [] __dev_queue_xmit+0x1d7/0x1c80 [ 38.564241] #2: (_xmit_NETROM){+.-...}, at: [] sch_direct_xmit+0x23c/0x6e0 [ 38.573689] #3: (rcu_read_lock){......}, at: [] dev_hard_start_xmit+0xa8/0x11c0 [ 38.583482] [ 38.583482] stack backtrace: [ 38.587959] CPU: 1 PID: 5772 Comm: syz-executor1 Not tainted 4.4.129-g23eaecc #26 [ 38.595551] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 38.604885] 0000000000000000 0a62100b74505e67 ffff8801d9b5ecc8 ffffffff81e0dc8d [ 38.612911] ffffffff853ed220 ffffffff853eb720 ffffffff853ed220 ffff8801d8bfd150 [ 38.620920] ffff8801d8bfc800 ffff8801d9b5ed10 ffffffff8140e3fb 0000000000000003 [ 38.628920] Call Trace: [ 38.631489] [] dump_stack+0xc1/0x124 [ 38.636829] [] print_circular_bug.cold.50+0x1bd/0x27d [ 38.643648] [] __lock_acquire+0x3902/0x5270 [ 38.649599] [] ? debug_check_no_locks_freed+0x210/0x210 [ 38.656594] [] ? trace_hardirqs_on_caller+0x266/0x590 [ 38.663411] [] lock_acquire+0x15e/0x450 [ 38.669017] [] ? ip_defrag+0x318/0x3fe0 [ 38.674619] [] ? inet_frag_find+0x22e/0x9c0 [ 38.680573] [] _raw_spin_lock+0x36/0x50 [ 38.686174] [] ? ip_defrag+0x318/0x3fe0 [ 38.691785] [] ip_defrag+0x318/0x3fe0 [ 38.697213] [] ? debug_check_no_locks_freed+0x210/0x210 [ 38.704208] [] ? memcpy+0x45/0x50 [ 38.709324] [] ? ip_expire+0x770/0x770 [ 38.714843] [] ip_check_defrag+0x3c8/0x7e0 [ 38.720704] [] ? ip_defrag+0x3fe0/0x3fe0 [ 38.726395] [] packet_rcv_fanout+0x52a/0x5e0 [ 38.732429] [] ? packet_bind+0x1a0/0x1a0 [ 38.738123] [] dev_hard_start_xmit+0x644/0x11c0 [ 38.745462] [] ? dev_hard_start_xmit+0xa8/0x11c0 [ 38.751860] [] sch_direct_xmit+0x2c1/0x6e0 [ 38.757723] [] ? dev_watchdog+0x7f0/0x7f0 [ 38.763496] [] __dev_queue_xmit+0xef3/0x1c80 [ 38.769532] [] ? __dev_queue_xmit+0x1d7/0x1c80 [ 38.775742] [] ? debug_check_no_locks_freed+0x210/0x210 [ 38.782730] [] ? netdev_pick_tx+0x2c0/0x2c0 [ 38.788687] [] ? memcpy+0x45/0x50 [ 38.793773] [] dev_queue_xmit+0x17/0x20 [ 38.799374] [] neigh_resolve_output+0x637/0x790 [ 38.805668] [] ? ip_finish_output2+0x6ab/0x1110 [ 38.811968] [] ip_finish_output2+0x6ab/0x1110 [ 38.818739] [] ? ip_finish_output2+0x212/0x1110 [ 38.825047] [] ? nf_ct_deliver_cached_events+0x335/0x560 [ 38.832130] [] ? nf_ct_deliver_cached_events+0x83/0x560 [ 38.839129] [] ? ip_copy_metadata+0x700/0x700 [ 38.845251] [] ? ip_options_fragment+0x1ac/0x280 [ 38.851633] [] ip_do_fragment+0x198b/0x2150 [ 38.857591] [] ? ip_copy_metadata+0x700/0x700 [ 38.863717] [] ip_fragment.constprop.50+0x143/0x200 [ 38.870360] [] ip_finish_output+0x6c4/0xbc0 [ 38.876314] [] ip_mc_output+0x233/0x980 [ 38.882009] [] ? ip_queue_xmit+0x1ab0/0x1ab0 [ 38.888049] [] ? ip_make_skb+0x116/0x210 [ 38.893738] [] ? ip_fragment.constprop.50+0x200/0x200 [ 38.900561] [] ? ip_flush_pending_frames+0x30/0x30 [ 38.907136] [] ip_local_out+0x9b/0x180 [ 38.912654] [] ip_send_skb+0x3c/0xc0 [ 38.917998] [] udp_send_skb+0x5c3/0xc60 [ 38.923601] [] udp_sendmsg+0x16ce/0x1bb0 [ 38.929287] [] ? ip_reply_glue_bits+0xc0/0xc0 [ 38.935413] [] ? udp4_lib_lookup+0x60/0x60 [ 38.941285] [] ? debug_check_no_locks_freed+0x210/0x210 [ 38.948450] [] ? sock_has_perm+0x1c1/0x400 [ 38.954315] [] ? sock_has_perm+0x29f/0x400 [ 38.960176] [] ? sock_has_perm+0x9f/0x400 [ 38.965948] [] ? inet_sendmsg+0x143/0x4d0 [ 38.971733] [] inet_sendmsg+0x203/0x4d0 [ 38.977334] [] ? inet_sendmsg+0x73/0x4d0 [ 38.983019] [] ? inet_recvmsg+0x4c0/0x4c0 [ 38.988829] [] sock_sendmsg+0xcc/0x110 [ 38.994361] [] SYSC_sendto+0x21c/0x370 [ 38.999905] [] ? SYSC_connect+0x300/0x300 [ 39.005737] [] ? ip4_datagram_connect+0x3a/0x50 [ 39.012067] [] ? inet_dgram_connect+0x11e/0x200 [ 39.018375] [] ? SYSC_connect+0x22a/0x300 [ 39.024165] [] ? compat_SyS_futex+0x1e1/0x2f0 [ 39.030294] [] ? fd_install+0x4d/0x60 [ 39.035745] [] ? compat_SyS_get_robust_list+0x310/0x310 [ 39.042743] [] ? SyS_socket+0x121/0x1b0 [ 39.048348] [] ? move_addr_to_kernel+0x50/0x50 [ 39.054568] [] SyS_sendto+0x40/0x50 [ 39.059824] [] ? SyS_getpeername+0x30/0x30 [ 39.065693] [] do_fast_syscall_32+0x326/0x8b0 [ 39.071822] [] sysenter_flags_fixed+0xd/0x17 2018/04/28 21:03:24 executed programs: 8 [ 39.113728] IPv6: ADDRCONF(NETDEV_CHANGE): veth0: link becomes ready [ 39.167177] random: nonblocking pool is initialized 2018/04/28 21:03:29 executed programs: 196