[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 19.089994] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. [ 20.285624] random: sshd: uninitialized urandom read (32 bytes read) Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 20.655206] random: sshd: uninitialized urandom read (32 bytes read) [ 21.386872] random: sshd: uninitialized urandom read (32 bytes read) [ 21.542649] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.59' (ECDSA) to the list of known hosts. [ 27.108561] random: sshd: uninitialized urandom read (32 bytes read) executing program [ 27.237898] BUG: please report to dccp@vger.kernel.org => prev = 0, last = 0 at net/dccp/ccids/lib/packet_history.c:425/tfrc_rx_hist_sample_rtt() [ 27.251431] CPU: 0 PID: 4495 Comm: syz-executor551 Not tainted 4.17.0-rc3+ #34 [ 27.258774] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 27.268109] Call Trace: [ 27.270676] [ 27.272819] dump_stack+0x1b9/0x294 [ 27.276430] ? dump_stack_print_info.cold.2+0x52/0x52 [ 27.281600] ? __sanitizer_cov_trace_const_cmp8+0x18/0x20 [ 27.287119] ? tfrc_rx_handle_loss+0x67c/0x1eb0 [ 27.291767] tfrc_rx_hist_sample_rtt.cold.3+0x54/0x5c [ 27.296936] ccid3_hc_rx_packet_recv+0x5c8/0xed0 [ 27.301671] ? ccid3_hc_tx_send_packet+0x880/0x880 [ 27.306580] dccp_deliver_input_to_ccids+0xf0/0x280 [ 27.311573] dccp_rcv_established+0x87/0xb0 [ 27.315874] dccp_v4_do_rcv+0x153/0x180 [ 27.319831] __sk_receive_skb+0x3a2/0xd60 [ 27.323957] ? sk_free+0x50/0x50 [ 27.327305] ? inet_lhash2_lookup+0x780/0x780 [ 27.331784] ? reqsk_fastopen_remove+0x670/0x670 [ 27.336527] ? __local_bh_enable_ip+0x161/0x230 [ 27.341179] ? dccp_invalid_packet+0x64/0x890 [ 27.345656] dccp_v4_rcv+0x10e5/0x1f3f [ 27.349528] ? dccp_v4_err+0x1840/0x1840 [ 27.353573] ? __lock_is_held+0xb5/0x140 [ 27.357619] ip_local_deliver_finish+0x2e3/0xd80 [ 27.362354] ? inet_add_protocol.cold.0+0x21/0x21 [ 27.367176] ? __sanitizer_cov_trace_cmp4+0x16/0x20 [ 27.372171] ? nf_hook_slow+0x11e/0x1c0 [ 27.376124] ip_local_deliver+0x1e1/0x720 [ 27.380251] ? __sanitizer_cov_trace_const_cmp1+0x1a/0x20 [ 27.385766] ? ip_call_ra_chain+0x720/0x720 [ 27.390066] ? __sanitizer_cov_trace_const_cmp1+0x1a/0x20 [ 27.395585] ? inet_add_protocol.cold.0+0x21/0x21 [ 27.400411] ip_rcv_finish+0x81b/0x2200 [ 27.404365] ? ip_local_deliver_finish+0xd80/0xd80 [ 27.409275] ? lock_downgrade+0x8e0/0x8e0 [ 27.413402] ? kasan_check_read+0x11/0x20 [ 27.417528] ? rcu_is_watching+0x85/0x140 [ 27.421654] ? rcu_bh_force_quiescent_state+0x20/0x20 [ 27.426827] ? __sanitizer_cov_trace_cmp4+0x16/0x20 [ 27.431824] ? nf_hook_slow+0x11e/0x1c0 [ 27.435777] ip_rcv+0xb70/0x143d [ 27.439122] ? ip_local_deliver+0x720/0x720 [ 27.443431] ? debug_check_no_locks_freed+0x310/0x310 [ 27.448596] ? __lock_acquire+0x7f5/0x5140 [ 27.452818] ? ip_local_deliver_finish+0xd80/0xd80 [ 27.457723] ? ip_local_deliver+0x720/0x720 [ 27.462032] __netif_receive_skb_core+0x26f5/0x3630 [ 27.467040] ? nf_ingress+0xa00/0xa00 [ 27.470824] ? __lock_acquire+0x7f5/0x5140 [ 27.475038] ? graph_lock+0x170/0x170 [ 27.478821] ? print_usage_bug+0xc0/0xc0 [ 27.482868] ? debug_check_no_locks_freed+0x310/0x310 [ 27.488048] ? __read_once_size_nocheck.constprop.8+0x10/0x10 [ 27.493910] ? secondary_startup_64+0xa5/0xb0 [ 27.498385] ? lock_downgrade+0x8e0/0x8e0 [ 27.502512] ? unwind_next_frame.part.7+0x1a9/0x9c0 [ 27.507514] ? unwind_dump+0x180/0x180 [ 27.511381] ? x86_64_start_kernel+0x76/0x79 [ 27.515766] ? x86_64_start_kernel+0x76/0x79 [ 27.520166] ? x86_64_start_kernel+0x47/0x79 [ 27.524554] ? graph_lock+0x170/0x170 [ 27.528332] ? is_bpf_text_address+0xd7/0x170 [ 27.532804] ? x86_64_start_kernel+0x76/0x79 [ 27.537194] ? kernel_text_address+0x79/0xf0 [ 27.541581] ? __unwind_start+0x166/0x330 [ 27.545709] ? unwind_next_frame+0x3e/0x50 [ 27.549922] ? __save_stack_trace+0x6e/0xd0 [ 27.554220] ? find_held_lock+0x36/0x1c0 [ 27.558258] ? print_usage_bug+0xc0/0xc0 [ 27.562299] ? lock_acquire+0x1dc/0x520 [ 27.566251] ? process_backlog+0x1a6/0x760 [ 27.570468] ? kasan_check_read+0x11/0x20 [ 27.574594] ? rcu_is_watching+0x85/0x140 [ 27.578719] ? rcu_bh_force_quiescent_state+0x20/0x20 [ 27.583888] __netif_receive_skb+0x2c/0x1e0 [ 27.588185] process_backlog+0x219/0x760 [ 27.592227] net_rx_action+0x7b7/0x1930 [ 27.596188] ? napi_complete_done+0x6a0/0x6a0 [ 27.600664] ? debug_check_no_locks_freed+0x310/0x310 [ 27.605831] ? kasan_check_read+0x11/0x20 [ 27.609957] ? rcu_is_watching+0x85/0x140 [ 27.614085] ? rcu_pm_notify+0xc0/0xc0 [ 27.617968] ? rcu_read_lock_sched_held+0x108/0x120 [ 27.622964] ? rcu_process_callbacks+0x5fa/0x15f0 [ 27.627790] ? call_rcu_sched+0x20/0x20 [ 27.631747] ? hrtimer_update_softirq_timer+0xa0/0xa0 [ 27.636914] ? graph_lock+0x170/0x170 [ 27.640696] ? find_held_lock+0x36/0x1c0 [ 27.644745] ? lock_downgrade+0x8e0/0x8e0 [ 27.648871] ? print_usage_bug+0xc0/0xc0 [ 27.652911] ? graph_lock+0x170/0x170 [ 27.656689] ? kasan_check_read+0x11/0x20 [ 27.660815] ? scheduler_ipi+0x1a0/0xa30 [ 27.664852] ? migration_cpu_stop+0x460/0x460 [ 27.669326] ? __lock_is_held+0xb5/0x140 [ 27.673374] __do_softirq+0x2e0/0xaf5 [ 27.677156] ? __irqentry_text_end+0x1f98a8/0x1f98a8 [ 27.682240] ? smp_reschedule_interrupt+0xed/0x660 [ 27.687147] ? smp_thermal_interrupt+0x800/0x800 [ 27.691880] ? _raw_spin_lock+0x32/0x40 [ 27.695833] ? _raw_spin_unlock+0x22/0x30 [ 27.699958] ? handle_edge_irq+0x330/0x870 [ 27.704173] ? task_prio+0x50/0x50 [ 27.707693] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 27.712515] do_softirq_own_stack+0x2a/0x40 [ 27.716813] [ 27.719037] do_softirq.part.17+0x14d/0x190 [ 27.723340] ? ip_finish_output2+0xa7f/0x1840 [ 27.727812] __local_bh_enable_ip+0x1ec/0x230 [ 27.732284] ip_finish_output2+0xab2/0x1840 [ 27.736584] ? trace_hardirqs_on+0xd/0x10 [ 27.740713] ? ip_copy_metadata+0xa90/0xa90 [ 27.745023] ? graph_lock+0x170/0x170 [ 27.748812] ? __sanitizer_cov_trace_const_cmp4+0x16/0x20 [ 27.754328] ? ipv4_mtu+0x375/0x580 [ 27.757937] ? __lock_is_held+0xb5/0x140 [ 27.761982] ip_finish_output+0x828/0xf80 [ 27.766109] ? ip_finish_output+0x828/0xf80 [ 27.770411] ? ip_fragment.constprop.49+0x240/0x240 [ 27.775405] ? kasan_check_read+0x11/0x20 [ 27.779531] ? rcu_is_watching+0x85/0x140 [ 27.783657] ? rcu_bh_force_quiescent_state+0x20/0x20 [ 27.788825] ? __sanitizer_cov_trace_cmp4+0x16/0x20 [ 27.793819] ? nf_hook_slow+0x11e/0x1c0 [ 27.797771] ip_output+0x21b/0x850 [ 27.801288] ? __ip_local_out+0x5cf/0xb20 [ 27.805413] ? ip_mc_output+0x15a0/0x15a0 [ 27.809543] ? ip_fragment.constprop.49+0x240/0x240 [ 27.814541] ip_local_out+0xc5/0x1b0 [ 27.818235] ip_queue_xmit+0x9d7/0x1f70 [ 27.822190] ? ip_build_and_send_pkt+0xc70/0xc70 [ 27.826925] ? skb_send_sock+0x50/0x50 [ 27.830791] ? reqsk_fastopen_remove+0x5e1/0x670 [ 27.835523] ? dccp_insert_option_padding+0xbc/0xe0 [ 27.840518] ? dccp_insert_options+0x24c/0xca0 [ 27.845077] ? dccp_v4_send_check+0x1a6/0x3d0 [ 27.849553] dccp_transmit_skb+0x999/0x12e0 [ 27.853860] dccp_xmit_packet+0x250/0x790 [ 27.857986] ? dccp_send_sync+0x270/0x270 [ 27.862115] ? __sanitizer_cov_trace_cmp4+0x16/0x20 [ 27.867112] ? ccid3_hc_tx_send_packet+0x35a/0x880 [ 27.872034] dccp_write_xmit+0x190/0x1f0 [ 27.876081] dccp_sendmsg+0x8c7/0x1020 [ 27.879952] ? dccp_getsockopt+0xf0/0xf0 [ 27.883995] ? rw_copy_check_uvector+0x2d3/0x3a0 [ 27.888739] ? __sanitizer_cov_trace_const_cmp8+0x18/0x20 [ 27.894255] ? import_iovec+0x24b/0x420 [ 27.898208] ? dup_iter+0x270/0x270 [ 27.901815] ? __sanitizer_cov_trace_const_cmp8+0x18/0x20 [ 27.907334] inet_sendmsg+0x19f/0x690 [ 27.911127] ? copy_msghdr_from_user+0x3bc/0x560 [ 27.915863] ? ipip_gro_receive+0x100/0x100 [ 27.920163] ? move_addr_to_kernel.part.18+0x100/0x100 [ 27.925421] ? security_socket_sendmsg+0x94/0xc0 [ 27.930156] ? ipip_gro_receive+0x100/0x100 [ 27.934457] sock_sendmsg+0xd5/0x120 [ 27.938154] ___sys_sendmsg+0x525/0x940 [ 27.942109] ? copy_msghdr_from_user+0x560/0x560 [ 27.946843] ? _raw_spin_unlock_irqrestore+0x74/0xc0 [ 27.952019] ? find_held_lock+0x36/0x1c0 [ 27.956065] ? __fget_light+0x2ef/0x430 [ 27.960034] ? fget_raw+0x20/0x20 [ 27.963465] ? lock_downgrade+0x8e0/0x8e0 [ 27.967591] ? lock_downgrade+0x8e0/0x8e0 [ 27.971719] ? trace_hardirqs_on_caller+0x421/0x5c0 [ 27.976718] ? __sanitizer_cov_trace_const_cmp8+0x18/0x20 [ 27.982233] ? sockfd_lookup_light+0xc5/0x160 [ 27.986707] __sys_sendmmsg+0x240/0x6f0 [ 27.990661] ? __ia32_sys_sendmsg+0xb0/0xb0 [ 27.994963] ? __sanitizer_cov_trace_const_cmp1+0x1a/0x20 [ 28.000477] ? fput+0x130/0x1a0 [ 28.003737] ? __sys_connect+0x1d1/0x4c0 [ 28.007778] ? inet6_hash+0x53/0xb0 [ 28.011386] ? __ia32_sys_accept+0xb0/0xb0 [ 28.015608] ? __x64_sys_futex+0x477/0x680 [ 28.019821] ? __sys_listen+0x23a/0x370 [ 28.023777] ? do_futex+0x27d0/0x27d0 [ 28.027563] ? move_addr_to_kernel+0x70/0x70 [ 28.031953] __x64_sys_sendmmsg+0x9d/0x100 [ 28.036169] do_syscall_64+0x1b1/0x800 [ 28.040036] ? finish_task_switch+0x1ca/0x810 [ 28.044510] ? syscall_return_slowpath+0x5c0/0x5c0 [ 28.049425] ? syscall_return_slowpath+0x30f/0x5c0 [ 28.054335] ? entry_SYSCALL_64_after_hwframe+0x59/0xbe [ 28.059694] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 28.064520] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 28.069684] RIP: 0033:0x445d09 [ 28.072851] RSP: 002b:00007f3c7eff5d88 EFLAGS: 00000293 ORIG_RAX: 0000000000000133 [ 28.080537] RAX: ffffffffffffffda RBX: 00000000006dac40 RCX: 0000000000445d09 [ 28.087792] RDX: 0000000000000001 RSI: 000000