[ 16.664748] random: sshd: uninitialized urandom read (32 bytes read, 32 bits of entropy available) [....] Starting file context maintaining daemon: restorecond[?25l[?1c7[1G[[32m ok [39;49m8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[?25l[?1c7[1G[[32m ok [39;49m8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 19.404708] random: sshd: uninitialized urandom read (32 bytes read, 36 bits of entropy available) [ 19.795130] random: sshd: uninitialized urandom read (32 bytes read, 36 bits of entropy available) [ 20.751935] random: sshd: uninitialized urandom read (32 bytes read, 106 bits of entropy available) [ 20.934465] random: sshd: uninitialized urandom read (32 bytes read, 110 bits of entropy available) Warning: Permanently added '10.128.0.29' (ECDSA) to the list of known hosts. [ 26.348262] random: sshd: uninitialized urandom read (32 bytes read, 118 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 [ 26.543863] ================================================================== [ 26.551255] BUG: KASAN: use-after-free in l2tp_session_queue_purge+0xe8/0x100 [ 26.558505] Read of size 4 at addr ffff8800b59fd400 by task syzkaller016241/3368 [ 26.566017] [ 26.567617] CPU: 1 PID: 3368 Comm: syzkaller016241 Not tainted 4.4.113-gef588ef #33 [ 26.575380] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 26.584703] 0000000000000000 41af1e5075f99087 ffff8801d16978c8 ffffffff81d0278d [ 26.592681] ffffea0002d67f00 ffff8800b59fd400 0000000000000000 ffff8800b59fd400 [ 26.600655] ffffffff82de6370 ffff8801d1697900 ffffffff814fd053 ffff8800b59fd400 [ 26.608627] Call Trace: [ 26.611197] [] dump_stack+0xc1/0x124 [ 26.616532] [] ? sock_release+0x1e0/0x1e0 [ 26.622330] [] print_address_description+0x73/0x260 [ 26.628966] [] ? sock_release+0x1e0/0x1e0 [ 26.634734] [] kasan_report+0x285/0x370 [ 26.640336] [] ? l2tp_session_queue_purge+0xe8/0x100 [ 26.647058] [] __asan_report_load4_noabort+0x14/0x20 [ 26.653781] [] l2tp_session_queue_purge+0xe8/0x100 [ 26.660332] [] ? sock_release+0x1e0/0x1e0 [ 26.666097] [] pppol2tp_release+0x1ff/0x310 [ 26.672037] [] sock_release+0x8d/0x1e0 [ 26.677545] [] sock_close+0x16/0x20 [ 26.682793] [] __fput+0x233/0x6d0 [ 26.687867] [] ____fput+0x15/0x20 [ 26.693026] [] task_work_run+0x104/0x180 [ 26.698707] [] do_exit+0x82a/0x2a10 [ 26.703953] [] ? __sigqueue_free.part.14+0x51/0x60 [ 26.710504] [] ? rcu_read_lock_sched_held+0x103/0x120 [ 26.717316] [] ? release_task+0x1240/0x1240 [ 26.723259] [] do_group_exit+0x108/0x320 [ 26.728942] [] get_signal+0x4f2/0x1550 [ 26.734461] [] do_signal+0x8b/0x1d40 [ 26.739796] [] ? setup_sigcontext+0x780/0x780 [ 26.745911] [] ? __lock_is_held+0xa1/0xf0 [ 26.751688] [] ? __bad_area_nosemaphore+0x220/0x420 [ 26.758338] [] ? bad_area+0x53/0x80 [ 26.763591] [] ? exit_to_usermode_loop+0xe4/0x160 [ 26.770055] [] exit_to_usermode_loop+0x11a/0x160 [ 26.776430] [] prepare_exit_to_usermode+0xe3/0x100 [ 26.782979] [] retint_user+0x8/0x3c [ 26.788222] [ 26.789821] Allocated by task 3367: [ 26.793414] [] save_stack_trace+0x26/0x50 [ 26.799306] [] save_stack+0x43/0xd0 [ 26.804671] [] kasan_kmalloc+0xad/0xe0 [ 26.810306] [] __kmalloc+0x124/0x320 [ 26.815756] [] l2tp_session_create+0x39/0x10f0 [ 26.822077] [] pppol2tp_connect+0x10fc/0x1930 [ 26.828309] [] SYSC_connect+0x1b6/0x310 [ 26.834020] [] SyS_connect+0x24/0x30 [ 26.839468] [] entry_SYSCALL_64_fastpath+0x1c/0x98 [ 26.846135] [ 26.847732] Freed by task 3318: [ 26.850977] [] save_stack_trace+0x26/0x50 [ 26.856861] [] save_stack+0x43/0xd0 [ 26.862237] [] kasan_slab_free+0x72/0xc0 [ 26.868038] [] kfree+0xfc/0x300 [ 26.873060] [] l2tp_session_free+0x170/0x200 [ 26.879204] [] l2tp_tunnel_closeall+0x2d1/0x3b0 [ 26.885609] [] l2tp_udp_encap_destroy+0x8b/0xf0 [ 26.892012] [] udpv6_destroy_sock+0xb1/0xd0 [ 26.898070] [] sk_common_release+0x6b/0x300 [ 26.904131] [] udp_lib_close+0x15/0x20 [ 26.909765] [] inet_release+0xfa/0x1d0 [ 26.915391] [] inet6_release+0x50/0x70 [ 26.921017] [] sock_release+0x8d/0x1e0 [ 26.926645] [] sock_close+0x16/0x20 [ 26.932007] [] __fput+0x233/0x6d0 [ 26.937194] [] ____fput+0x15/0x20 [ 26.942385] [] task_work_run+0x104/0x180 [ 26.948183] [] do_exit+0x82a/0x2a10 [ 26.953547] [] do_group_exit+0x108/0x320 [ 26.959340] [] get_signal+0x4f2/0x1550 [ 26.964965] [] do_signal+0x8b/0x1d40 [ 26.970420] [] exit_to_usermode_loop+0x11a/0x160 [ 26.976911] [] prepare_exit_to_usermode+0xe3/0x100 [ 26.983590] [] retint_user+0x8/0x3c [ 26.988958] [ 26.990558] The buggy address belongs to the object at ffff8800b59fd400 [ 26.990558] which belongs to the cache kmalloc-512 of size 512 [ 27.003186] The buggy address is located 0 bytes inside of [ 27.003186] 512-byte region [ffff8800b59fd400, ffff8800b59fd600) [ 27.014856] The buggy address belongs to the page: [ 27.022840] kasan: CONFIG_KASAN_INLINE enabled [ 27.027255] kasan: GPF could be caused by NULL-ptr deref or user memory access[ 27.034717] ------------[ cut here ]------------ [ 27.039469] WARNING: CPU: 0 PID: 0 at kernel/rcu/update.c:211 __rcu_read_unlock+0x140/0x1a0() [ 27.048116] Kernel panic - not syncing: panic_on_warn set ... [ 27.048116] [ 27.055482] CPU: 0 PID: 0 Comm: Not tainted 4.4.113-gef588ef #33 [ 27.061707] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 27.071078] 0000000000000000 0ac9655ecd9d0b53 ffff8801db207a08 ffffffff81d0278d [ 27.079132] ffffffff838439a0 ffff8801db207ae0 ffffffff83865c60 0000000000000009 [ 27.087182] 00000000000000d3 ffff8801db207ad0 ffffffff81419b6a 0000000041b58ab3 [ 27.095240] Call Trace: [ 27.097805] [] dump_stack+0xc1/0x124 [ 27.103916] [] panic+0x1aa/0x388 [ 27.108933] [] ? percpu_up_read.constprop.45+0xe1/0xe1 [ 27.115868] [] ? pm_qos_get_value.part.4+0xb/0xb [ 27.122276] [] ? warn_slowpath_common+0x10a/0x140 [ 27.128772] [] warn_slowpath_common+0x125/0x140 [ 27.135088] [] ? __rcu_read_unlock+0x140/0x1a0 [ 27.141326] [] warn_slowpath_null+0x29/0x30 [ 27.147301] [] __rcu_read_unlock+0x140/0x1a0 [ 27.153363] [] atomic_notifier_call_chain+0x9e/0x140 [ 27.160119] [] ? __atomic_notifier_call_chain+0x150/0x150 [ 27.167310] [] notify_die+0xdf/0x160 [ 27.172671] [] ? atomic_notifier_call_chain+0x140/0x140 [ 27.179687] [] ? scheduler_tick+0xc4/0x300 [ 27.185575] [] ? search_exception_tables+0x31/0x40 [ 27.192171] [] do_general_protection+0x2f7/0x390 [ 27.198579] [] general_protection+0x28/0x30 [ 27.204560] [] ? scheduler_tick+0xc4/0x300 [ 27.210447] [] update_process_times+0x5c/0x70 [ 27.216592] [] tick_sched_handle.isra.16+0x55/0xf0 [ 27.223194] [] tick_sched_timer+0x72/0x120 [ 27.229082] [] ? tick_sched_do_timer+0xa0/0xa0 [ 27.235317] [] __hrtimer_run_queues+0x306/0xfe0 [ 27.241631] [] ? hrtimer_fixup_init+0x70/0x70 [ 27.247773] [] ? hrtimer_interrupt+0x131/0x440 [ 27.254011] [] hrtimer_interrupt+0x1a6/0x440 [ 27.260071] [] local_apic_timer_interrupt+0x6a/0xb0 [ 27.266736] [] smp_apic_timer_interrupt+0x76/0xa0 [ 27.273229] [] apic_timer_interrupt+0xa0/0xb0 [ 27.279367] [ 28.390019] Shutting down cpus with NMI [ 28.394812] Dumping ftrace buffer: [ 28.398338] (ftrace buffer empty) [ 28.402024] Kernel Offset: disabled [ 28.405615] ------------[ cut here ]------------ [ 28.410344] WARNING: CPU: 0 PID: 0 at kernel/rcu/update.c:211 __rcu_read_unlock+0x140/0x1a0() [ 28.418970] Modules linked in: [ 28.422256] CPU: 0 PID: 0 Comm: Not tainted 4.4.113-gef588ef #33 [ 28.428460] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 28.437795] 0000000000000000 0ac9655ecd9d0b53 ffff8801db207958 ffffffff81d0278d [ 28.445762] 0000000000000000 ffff8801d0fcdf00 ffffffff83865c60 0000000000000009 [ 28.453721] 00000000000000d3 ffff8801db207998 ffffffff8112d889 ffffffff81285280 [ 28.461678] Call Trace: [ 28.464228] [] dump_stack+0xc1/0x124 [ 28.470289] [] warn_slowpath_common+0xd9/0x140 [ 28.476493] [] ? __rcu_read_unlock+0x140/0x1a0 [ 28.482694] [] warn_slowpath_null+0x29/0x30 [ 28.488632] [] __rcu_read_unlock+0x140/0x1a0 [ 28.494658] [] atomic_notifier_call_chain+0x9e/0x140 [ 28.501375] [] ? __atomic_notifier_call_chain+0x150/0x150 [ 28.508529] [] panic+0x209/0x388 [ 28.513511] [] ? percpu_up_read.constprop.45+0xe1/0xe1 [ 28.520411] [] ? pm_qos_get_value.part.4+0xb/0xb [ 28.526792] [] ? warn_slowpath_common+0x10a/0x140 [ 28.533257] [] warn_slowpath_common+0x125/0x140 [ 28.539541] [] ? __rcu_read_unlock+0x140/0x1a0 [ 28.545746] [] warn_slowpath_null+0x29/0x30 [ 28.551686] [] __rcu_read_unlock+0x140/0x1a0 [ 28.557710] [] atomic_notifier_call_chain+0x9e/0x140 [ 28.564428] [] ? __atomic_notifier_call_chain+0x150/0x150 [ 28.571582] [] notify_die+0xdf/0x160 [ 28.576913] [] ? atomic_notifier_call_chain+0x140/0x140 [ 28.583893] [] ? scheduler_tick+0xc4/0x300 [ 28.589745] [] ? search_exception_tables+0x31/0x40 [ 28.596290] [] do_general_protection+0x2f7/0x390 [ 28.602671] [] general_protection+0x28/0x30 [ 28.608608] [] ? scheduler_tick+0xc4/0x300 [ 28.614466] [] update_process_times+0x5c/0x70 [ 28.620584] [] tick_sched_handle.isra.16+0x55/0xf0 [ 28.627136] [] tick_sched_timer+0x72/0x120 [ 28.632987] [] ? tick_sched_do_timer+0xa0/0xa0 [ 28.639185] [] __hrtimer_run_queues+0x306/0xfe0 [ 28.645471] [] ? hrtimer_fixup_init+0x70/0x70 [ 28.651583] [] ? hrtimer_interrupt+0x131/0x440 [ 28.657783] [] hrtimer_interrupt+0x1a6/0x440 [ 28.663809] [] local_apic_timer_interrupt+0x6a/0xb0 [ 28.670447] [] smp_apic_timer_interrupt+0x76/0xa0 [ 28.676907] [] apic_timer_interrupt+0xa0/0xb0 [ 28.683021] [ 28.685050] ---[ end trace 77b297afdbe2f4a4 ]--- [ 28.690061] Rebooting in 86400 seconds..