[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 20.631132] random: sshd: uninitialized urandom read (32 bytes read, 32 bits of entropy available) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 22.324823] random: sshd: uninitialized urandom read (32 bytes read, 34 bits of entropy available) [ 22.655502] random: sshd: uninitialized urandom read (32 bytes read, 35 bits of entropy available) [ 23.904156] random: sshd: uninitialized urandom read (32 bytes read, 117 bits of entropy available) [ 24.087363] random: sshd: uninitialized urandom read (32 bytes read, 119 bits of entropy available) Warning: Permanently added '10.128.0.9' (ECDSA) to the list of known hosts. [ 29.635774] random: sshd: uninitialized urandom read (32 bytes read, 125 bits of entropy available) executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program [ 30.538399] random: nonblocking pool is initialized executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program [ 37.460938] ================================================================== [ 37.468363] BUG: KASAN: use-after-free in l2tp_session_queue_purge+0xf4/0x100 [ 37.475634] Read of size 4 at addr ffff8801d4abdb80 by task syz-executor050/8182 [ 37.483205] [ 37.484836] CPU: 0 PID: 8182 Comm: syz-executor050 Not tainted 4.4.139-g7ba5557 #65 [ 37.492618] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 37.501967] 0000000000000000 f0f6a453b0623f52 ffff8801d463fcc0 ffffffff81e0d58d [ 37.509973] ffffea000752af00 ffff8801d4abdb80 0000000000000000 ffff8801d4abdb80 [ 37.517993] ffffffff82f19100 ffff8801d463fcf8 ffffffff81515a16 ffff8801d4abdb80 [ 37.526020] Call Trace: [ 37.528606] [] dump_stack+0xc1/0x124 [ 37.533961] [] ? sock_release+0x1c0/0x1c0 [ 37.539749] [] print_address_description+0x6c/0x216 [ 37.546434] [] ? sock_release+0x1c0/0x1c0 [ 37.552238] [] kasan_report.cold.7+0x175/0x2f7 [ 37.558458] [] ? l2tp_session_queue_purge+0xf4/0x100 [ 37.565194] [] __asan_report_load4_noabort+0x14/0x20 [ 37.571935] [] l2tp_session_queue_purge+0xf4/0x100 [ 37.578510] [] ? sock_release+0x1c0/0x1c0 [ 37.584293] [] pppol2tp_release+0x1ff/0x310 [ 37.590247] [] sock_release+0x96/0x1c0 [ 37.595761] [] sock_close+0x16/0x20 [ 37.601014] [] __fput+0x235/0x6f0 [ 37.606090] [] ____fput+0x15/0x20 [ 37.611169] [] task_work_run+0x10f/0x190 [ 37.616855] [] exit_to_usermode_loop+0x13d/0x160 [ 37.623234] [] syscall_return_slowpath+0x1b5/0x1f0 [ 37.629791] [] int_ret_from_sys_call+0x25/0xa3 [ 37.635994] [ 37.637597] Allocated by task 8182: [ 37.641192] [] save_stack_trace+0x26/0x50 [ 37.647087] [] save_stack+0x43/0xd0 [ 37.652466] [] kasan_kmalloc+0xc7/0xe0 [ 37.658117] [] __kmalloc+0x124/0x310 [ 37.663573] [] l2tp_session_create+0x39/0x1030 [ 37.669916] [] pppol2tp_connect+0x10f0/0x1910 [ 37.676155] [] SYSC_connect+0x1b8/0x300 [ 37.681891] [] SyS_connect+0x24/0x30 [ 37.687365] [] entry_SYSCALL_64_fastpath+0x22/0x9e [ 37.694059] [ 37.695671] Freed by task 8183: [ 37.698921] [] save_stack_trace+0x26/0x50 [ 37.704821] [] save_stack+0x43/0xd0 [ 37.710214] [] kasan_slab_free+0x72/0xc0 [ 37.716025] [] kfree+0xf4/0x310 [ 37.721071] [] l2tp_session_free+0x170/0x200 [ 37.727229] [] l2tp_tunnel_closeall+0x2b9/0x350 [ 37.733660] [] l2tp_udp_encap_destroy+0x8b/0xf0 [ 37.740107] [] udpv6_destroy_sock+0xb1/0xd0 [ 37.746206] [] sk_common_release+0x6d/0x300 [ 37.752304] [] udp_lib_close+0x15/0x20 [ 37.757950] [] inet_release+0xff/0x1d0 [ 37.763589] [] inet6_release+0x50/0x70 [ 37.769231] [] sock_release+0x96/0x1c0 [ 37.774882] [] sock_close+0x16/0x20 [ 37.780262] [] __fput+0x235/0x6f0 [ 37.785468] [] ____fput+0x15/0x20 [ 37.790671] [] task_work_run+0x10f/0x190 [ 37.796499] [] exit_to_usermode_loop+0x13d/0x160 [ 37.803016] [] syscall_return_slowpath+0x1b5/0x1f0 [ 37.809712] [] int_ret_from_sys_call+0x25/0xa3 [ 37.816049] [ 37.817674] The buggy address belongs to the object at ffff8801d4abdb80 [ 37.817674] which belongs to the cache kmalloc-512 of size 512 [ 37.830319] The buggy address is located 0 bytes inside of [ 37.830319] 512-byte region [ffff8801d4abdb80, ffff8801d4abdd80) [ 37.842000] The buggy address belongs to the page: [ 37.847242] kasan: CONFIG_KASAN_INLINE enabled [ 37.851702] ------------[ cut here ]------------ [ 37.851725] WARNING: CPU: 1 PID: 3843 at lib/debugobjects.c:263 debug_print_object+0x181/0x210() [ 37.851737] ODEBUG: deactivate not available (active state 0) object type: hrtimer hint: hrtimer_wakeup+0x0/0x60 [ 37.851742] Kernel panic - not syncing: panic_on_warn set ... [ 37.851742] [ 37.851750] CPU: 1 PID: 3843 Comm: syz-executor050 Not tainted 4.4.139-g7ba5557 #65 [ 37.851753] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 37.851757] 0000000000000000 22d246aaaf08e1f7 ffff8801db307aa8 ffffffff81e0d58d [ 37.851765] ffffffff83a43da0 ffff8800bb90e000 ffffffff83c139c0 0000000000000009 [ 37.851773] 0000000000000107 ffff8801db307b68 ffffffff8140a184 0000000041b58ab3 [ 37.851781] Call Trace: [ 37.851783] [] dump_stack+0xc1/0x124 [ 37.851802] [] panic+0x19e/0x38d [ 37.851809] [] ? add_taint.cold.4+0x16/0x16 [ 37.851815] [] ? warn_slowpath_common.cold.6+0x5/0x20 [ 37.851821] [] warn_slowpath_common.cold.6+0x20/0x20 [ 37.851827] [] ? debug_print_object+0x181/0x210 [ 37.851833] [] ? ktime_add_safe+0x150/0x150 [ 37.851842] [] warn_slowpath_fmt+0xbf/0x100 [ 37.851849] [] ? warn_slowpath_common+0x120/0x120 [ 37.851859] [] ? check_preempt_curr+0x2a8/0x3e0 [ 37.851866] [] debug_print_object+0x181/0x210 [ 37.851871] [] ? clock_was_set_work+0x30/0x30 [ 37.851878] [] debug_object_deactivate+0x208/0x340 [ 37.851885] [] ? debug_object_activate+0x480/0x480 [ 37.851891] [] __hrtimer_run_queues+0x222/0x1000 [ 37.851896] [] ? retrigger_next_event+0x1c0/0x1c0 [ 37.851904] [] ? kvm_clock_read+0x23/0x40 [ 37.851910] [] ? kvm_clock_get_cycles+0x9/0x10 [ 37.851916] [] ? hrtimer_interrupt+0x12d/0x430 [ 37.851921] [] hrtimer_interrupt+0x1b1/0x430 [ 37.851930] [] local_apic_timer_interrupt+0x74/0xa0 [ 37.851940] [] smp_apic_timer_interrupt+0x7c/0xa0 [ 37.851946] [] apic_timer_interrupt+0xa0/0xb0 [ 37.851948] [] ? console_unlock+0x8c4/0xa10 [ 37.851960] [] ? console_unlock+0x8ce/0xa10 [ 37.851967] [] ? _raw_spin_unlock_irqrestore+0x45/0x70 [ 37.851972] [] ? vprintk_emit+0x3af/0x840 [ 37.851977] [] vprintk_emit+0x51e/0x840 [ 37.851983] [] vprintk+0x28/0x30 [ 37.851989] [] vprintk_default+0x1d/0x30 [ 37.851996] [] printk+0xaf/0xd7 [ 37.852003] [] ? log_wakeup_reason.cold.1+0x13f/0x13f [ 37.852010] [] ? check_preemption_disabled+0x3b/0x170 [ 37.852017] [] ? kasan_die_handler.cold.3+0x5/0x22 [ 37.852023] [] kasan_die_handler.cold.3+0x11/0x22 [ 37.852031] [] notifier_call_chain+0xb9/0x1e0 [ 37.852038] [] atomic_notifier_call_chain+0x7f/0x140 [ 37.852045] [] ? blocking_notifier_call_chain+0xa0/0xa0 [ 37.852050] [] notify_die+0xdf/0x160 [ 37.852057] [] ? atomic_notifier_call_chain+0x140/0x140 [ 37.852065] [] ? task_has_perm+0xed/0x330 [ 37.852072] [] ? search_exception_tables+0x31/0x40 [ 37.852080] [] do_general_protection+0x20a/0x2b0 [ 37.852087] [] general_protection+0x28/0x30 [ 37.852093] [] ? task_has_perm+0xb2/0x330 [ 37.852099] [] ? task_has_perm+0xed/0x330 [ 37.852105] [] ? selinux_sb_show_options+0xdc0/0xdc0 [ 37.852112] [] selinux_task_wait+0x23/0x30 [ 37.852120] [] security_task_wait+0x73/0xb0 [ 37.852125] [] wait_consider_task+0x298/0x3600 [ 37.852131] [] ? complete_and_exit+0x40/0x40 [ 37.852135] [] ? do_wait+0x2cc/0xa30 [ 37.852140] [] do_wait+0x364/0xa30 [ 37.852145] [] ? wait_consider_task+0x3600/0x3600 [ 37.852151] [] SyS_wait4+0x12b/0x1f0 [ 37.852156] [] ? SyS_waitid+0x2d0/0x2d0 [ 37.852161] [] ? kill_orphaned_pgrp+0x390/0x390 [ 37.852167] [] ? lockdep_sys_exit_thunk+0x12/0x14 [ 37.852174] [] entry_SYSCALL_64_fastpath+0x22/0x9e [ 38.981506] Shutting down cpus with NMI [ 38.982520] Dumping ftrace buffer: [ 38.982523] (ftrace buffer empty) [ 38.982526] Kernel Offset: disabled [ 39.435083] Rebooting in 86400 seconds..