[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 21.096295] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 24.745834] random: sshd: uninitialized urandom read (32 bytes read) [ 24.966702] random: sshd: uninitialized urandom read (32 bytes read) [ 25.468806] random: sshd: uninitialized urandom read (32 bytes read) [ 27.484543] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.40' (ECDSA) to the list of known hosts. [ 33.260028] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program executing program executing program executing program executing program executing program executing program [ 34.341667] ================================================================== [ 34.349256] BUG: KASAN: use-after-free in finish_task_switch+0x544/0x870 [ 34.356115] Read of size 8 at addr ffff8801c79482d8 by task syz-executor216/4445 [ 34.363655] [ 34.365302] CPU: 0 PID: 4445 Comm: syz-executor216 Not tainted 4.18.0-rc8-next-20180810+ #36 [ 34.373893] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 34.383267] Call Trace: [ 34.385875] dump_stack+0x1c9/0x2b4 [ 34.389528] ? dump_stack_print_info.cold.2+0x52/0x52 [ 34.394747] ? printk+0xa7/0xcf [ 34.398053] ? kmsg_dump_rewind_nolock+0xe4/0xe4 [ 34.402835] ? finish_task_switch+0x544/0x870 [ 34.407354] print_address_description+0x6c/0x20b [ 34.412643] ? finish_task_switch+0x544/0x870 [ 34.417160] kasan_report.cold.7+0x242/0x30d [ 34.421594] __asan_report_load8_noabort+0x14/0x20 [ 34.426543] finish_task_switch+0x544/0x870 [ 34.430886] ? __switch_to_asm+0x34/0x70 [ 34.434973] ? preempt_notifier_register+0x200/0x200 [ 34.440092] ? __switch_to_asm+0x34/0x70 [ 34.444170] ? __switch_to_asm+0x34/0x70 [ 34.448250] ? __switch_to_asm+0x40/0x70 [ 34.452331] ? __switch_to_asm+0x34/0x70 [ 34.456411] ? __switch_to_asm+0x40/0x70 [ 34.460514] ? __switch_to_asm+0x34/0x70 [ 34.464588] ? __switch_to_asm+0x40/0x70 [ 34.468791] ? __switch_to_asm+0x34/0x70 [ 34.472871] ? __switch_to_asm+0x34/0x70 [ 34.476947] ? __switch_to_asm+0x40/0x70 [ 34.481023] ? __switch_to_asm+0x34/0x70 [ 34.485174] ? __switch_to_asm+0x40/0x70 [ 34.489252] ? __switch_to_asm+0x34/0x70 [ 34.493334] ? __switch_to_asm+0x40/0x70 [ 34.497421] __schedule+0x884/0x1ec0 [ 34.501182] ? __sched_text_start+0x8/0x8 [ 34.505357] ? graph_lock+0x170/0x170 [ 34.509176] ? plist_check_list+0xa0/0xa0 [ 34.513353] ? __lock_acquire+0x7fc/0x5020 [ 34.517631] schedule+0xfb/0x450 [ 34.521023] ? lock_downgrade+0x8f0/0x8f0 [ 34.525193] ? __schedule+0x1ec0/0x1ec0 [ 34.529189] ? kasan_check_read+0x11/0x20 [ 34.533357] ? do_raw_spin_unlock+0xa7/0x2f0 [ 34.537788] ? do_raw_spin_trylock+0x1c0/0x1c0 [ 34.542391] ? lock_acquire+0x1e4/0x540 [ 34.546397] futex_wait_queue_me+0x3f9/0x840 [ 34.550823] ? graph_lock+0x170/0x170 [ 34.554642] ? refill_pi_state_cache.part.8+0x320/0x320 [ 34.560026] ? kasan_check_write+0x14/0x20 [ 34.564284] ? do_raw_spin_lock+0xc1/0x200 [ 34.568547] ? __sanitizer_cov_trace_const_cmp4+0x16/0x20 [ 34.574110] ? get_futex_value_locked+0xcb/0xf0 [ 34.578807] ? __sanitizer_cov_trace_cmp4+0x16/0x20 [ 34.583844] ? futex_wait_setup+0x281/0x410 [ 34.588186] ? find_held_lock+0x36/0x1c0 [ 34.592272] ? futex_wake+0x760/0x760 [ 34.596098] ? __sanitizer_cov_trace_switch+0x53/0x90 [ 34.601311] futex_wait+0x45b/0xa20 [ 34.604969] ? rcu_cleanup_dead_rnp+0x200/0x200 [ 34.609664] ? futex_wait_setup+0x410/0x410 [ 34.614012] ? __sanitizer_cov_trace_switch+0x53/0x90 [ 34.619225] ? __sanitizer_cov_trace_const_cmp1+0x1a/0x20 [ 34.624850] ? drop_futex_key_refs.isra.14+0x6d/0xe0 [ 34.630039] ? futex_wake+0x304/0x760 [ 34.633889] ? save_stack+0xa9/0xd0 [ 34.637539] ? __kasan_slab_free+0x11a/0x170 [ 34.641966] ? kasan_slab_free+0xe/0x10 [ 34.646066] ? kmem_cache_free+0x86/0x2d0 [ 34.650234] ? putname+0xf2/0x130 [ 34.653709] ? filename_lookup+0x397/0x510 [ 34.657976] do_futex+0x336/0x27d0 [ 34.661542] ? kasan_check_read+0x11/0x20 [ 34.665716] ? do_raw_spin_unlock+0xa7/0x2f0 [ 34.670155] ? do_raw_spin_trylock+0x1c0/0x1c0 [ 34.674761] ? kasan_check_write+0x14/0x20 [ 34.679016] ? do_raw_spin_lock+0xc1/0x200 [ 34.683273] ? exit_robust_list+0x290/0x290 [ 34.687622] ? _raw_spin_unlock_irqrestore+0x63/0xc0 [ 34.692756] ? debug_check_no_obj_freed+0x30b/0x595 [ 34.697801] ? path_lookupat.isra.45+0x381/0xc00 [ 34.702582] ? kasan_check_read+0x11/0x20 [ 34.706761] ? rcu_is_watching+0x8c/0x150 [ 34.710931] ? rcu_pm_notify+0xc0/0xc0 [ 34.714841] ? putname+0xf2/0x130 [ 34.718320] ? putname+0xf2/0x130 [ 34.721797] ? rcu_read_lock_sched_held+0x108/0x120 [ 34.726840] ? kmem_cache_free+0x25c/0x2d0 [ 34.731096] ? putname+0xf7/0x130 [ 34.734574] ? filename_lookup+0x39c/0x510 [ 34.738827] ? nd_jump_link+0x1d0/0x1d0 [ 34.742835] ? mpi_free.cold.1+0x19/0x19 [ 34.746927] ? __sanitizer_cov_trace_const_cmp4+0x16/0x20 [ 34.752502] ? getname_flags+0x26e/0x5a0 [ 34.756581] ? user_path_at_empty+0x40/0x50 [ 34.760924] ? __sanitizer_cov_trace_const_cmp4+0x16/0x20 [ 34.766491] ? do_linkat+0x3ec/0xaa0 [ 34.770278] __x64_sys_futex+0x472/0x6a0 [ 34.774357] ? do_futex+0x27d0/0x27d0 [ 34.778174] ? filp_open+0x80/0x80 [ 34.781745] ? do_syscall_64+0x9a/0x820 [ 34.785747] do_syscall_64+0x1b9/0x820 [ 34.789645] ? finish_task_switch+0x1d3/0x870 [ 34.794153] ? syscall_return_slowpath+0x5e0/0x5e0 [ 34.799093] ? syscall_return_slowpath+0x31d/0x5e0 [ 34.804036] ? entry_SYSCALL_64_after_hwframe+0x59/0xbe [ 34.809416] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 34.814270] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 34.819466] RIP: 0033:0x4468a9 [ 34.822671] Code: e8 0c e8 ff ff 48 83 c4 18 c3 0f 1f 80 00 00 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 7b 08 fc ff c3 66 2e 0f 1f 84 00 00 00 00 [ 34.841582] RSP: 002b:00007f34d3e78da8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca [ 34.849296] RAX: ffffffffffffffda RBX: 00000000006dbc88 RCX: 00000000004468a9 [ 34.856571] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 00000000006dbc88 [ 34.863850] RBP: 00000000006dbc80 R08: 0000000000000000 R09: 0000000000000000 [ 34.871124] R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006dbc8c [ 34.878401] R13: 0030656c69662f2e R14: 6c75662f7665642f R15: 00000000006dbd6c [ 34.885686] [ 34.887326] Allocated by task 4439: [ 34.890988] save_stack+0x43/0xd0 [ 34.894451] kasan_kmalloc+0xc4/0xe0 [ 34.898174] kasan_slab_alloc+0x12/0x20 [ 34.902160] kmem_cache_alloc+0x12e/0x760 [ 34.906318] vmx_create_vcpu+0xcf/0x28b0 [ 34.910386] kvm_arch_vcpu_create+0xe5/0x220 [ 34.914811] kvm_vm_ioctl+0x488/0x1d80 [ 34.918709] do_vfs_ioctl+0x1de/0x1720 [ 34.922611] ksys_ioctl+0xa9/0xd0 [ 34.926074] __x64_sys_ioctl+0x73/0xb0 [ 34.929977] do_syscall_64+0x1b9/0x820 [ 34.933876] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 34.939083] [ 34.940728] Freed by task 4423: [ 34.944019] save_stack+0x43/0xd0 [ 34.947482] __kasan_slab_free+0x11a/0x170 [ 34.951733] kasan_slab_free+0xe/0x10 [ 34.955542] kmem_cache_free+0x86/0x2d0 [ 34.959528] vmx_free_vcpu+0x26b/0x300 [ 34.963425] kvm_arch_destroy_vm+0x365/0x7c0 [ 34.967850] kvm_put_kvm+0x73f/0x1060 [ 34.971672] kvm_vcpu_release+0x7b/0xa0 [ 34.975655] __fput+0x376/0x8a0 [ 34.978948] ____fput+0x15/0x20 [ 34.982242] task_work_run+0x1e8/0x2a0 [ 34.986144] exit_to_usermode_loop+0x318/0x380 [ 34.990743] do_syscall_64+0x6be/0x820 [ 34.994648] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 34.999843] [ 35.001505] The buggy address belongs to the object at ffff8801c79482c0 [ 35.001505] which belongs to the cache kvm_vcpu of size 23808 [ 35.014089] The buggy address is located 24 bytes inside of [ 35.014089] 23808-byte region [ffff8801c79482c0, ffff8801c794dfc0) [ 35.026058] The buggy address belongs to the page: [ 35.031000] page:ffffea00071e5200 count:1 mapcount:0 mapping:ffff8801d4c35a80 index:0x0 compound_mapcount: 0 executing program [ 35.040988] flags: 0x2fffc0000008100(slab|head) [ 35.045695] raw: 02fffc0000008100 ffffea000721fe08 ffffea0007364208 ffff8801d4c35a80 [ 35.053601] raw: 0000000000000000 ffff8801c79482c0 0000000100000001 0000000000000000 [ 35.061504] page dumped because: kasan: bad access detected [ 35.067274] [ 35.068902] Memory state around the buggy address: [ 35.073846] ffff8801c7948180: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 35.081219] ffff8801c7948200: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 35.088587] >ffff8801c7948280: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb [ 35.095954] ^ [ 35.102200] ffff8801c7948300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 35.109576] ffff8801c7948380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 35.116953] ================================================================== [ 35.124319] Disabling lock debugging due to kernel taint [ 35.129908] Kernel panic - not syncing: panic_on_warn set ... [ 35.129908] [ 35.137306] CPU: 0 PID: 4445 Comm: syz-executor216 Tainted: G B 4.18.0-rc8-next-20180810+ #36 [ 35.147353] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 35.156831] Call Trace: [ 35.159533] dump_stack+0x1c9/0x2b4 [ 35.163181] ? dump_stack_print_info.cold.2+0x52/0x52 [ 35.168392] ? trace_hardirqs_on_thunk+0x1a/0x1c [ 35.173163] panic+0x238/0x4e7 [ 35.176384] ? add_taint.cold.5+0x16/0x16 [ 35.180560] ? do_raw_spin_unlock+0xa7/0x2f0 [ 35.184987] ? finish_task_switch+0x544/0x870 [ 35.189517] kasan_end_report+0x47/0x4f [ 35.193525] kasan_report.cold.7+0x76/0x30d [ 35.197984] __asan_report_load8_noabort+0x14/0x20 [ 35.202932] finish_task_switch+0x544/0x870 [ 35.207273] ? __switch_to_asm+0x34/0x70 [ 35.211349] ? preempt_notifier_register+0x200/0x200 [ 35.216491] ? __switch_to_asm+0x34/0x70 [ 35.220573] ? __switch_to_asm+0x34/0x70 [ 35.224657] ? __switch_to_asm+0x40/0x70 [ 35.228740] ? __switch_to_asm+0x34/0x70 [ 35.232820] ? __switch_to_asm+0x40/0x70 [ 35.236897] ? __switch_to_asm+0x34/0x70 [ 35.241059] ? __switch_to_asm+0x40/0x70 [ 35.245132] ? __switch_to_asm+0x34/0x70 [ 35.249207] ? __switch_to_asm+0x34/0x70 [ 35.253286] ? __switch_to_asm+0x40/0x70 [ 35.257365] ? __switch_to_asm+0x34/0x70 [ 35.261444] ? __switch_to_asm+0x40/0x70 [ 35.265546] ? __switch_to_asm+0x34/0x70 [ 35.269632] ? __switch_to_asm+0x40/0x70 [ 35.273728] __schedule+0x884/0x1ec0 [ 35.278028] ? __sched_text_start+0x8/0x8 [ 35.282196] ? graph_lock+0x170/0x170 [ 35.286014] ? plist_check_list+0xa0/0xa0 [ 35.290178] ? __lock_acquire+0x7fc/0x5020 [ 35.294439] schedule+0xfb/0x450 [ 35.297846] ? lock_downgrade+0x8f0/0x8f0 [ 35.302034] ? __schedule+0x1ec0/0x1ec0 [ 35.306029] ? kasan_check_read+0x11/0x20 [ 35.310193] ? do_raw_spin_unlock+0xa7/0x2f0 [ 35.314620] ? do_raw_spin_trylock+0x1c0/0x1c0 [ 35.319216] ? lock_acquire+0x1e4/0x540 [ 35.323219] futex_wait_queue_me+0x3f9/0x840 [ 35.327649] ? graph_lock+0x170/0x170 [ 35.331498] ? refill_pi_state_cache.part.8+0x320/0x320 [ 35.336882] ? kasan_check_write+0x14/0x20 [ 35.341135] ? do_raw_spin_lock+0xc1/0x200 [ 35.345394] ? __sanitizer_cov_trace_const_cmp4+0x16/0x20 [ 35.350943] ? get_futex_value_locked+0xcb/0xf0 [ 35.355631] ? __sanitizer_cov_trace_cmp4+0x16/0x20 [ 35.360672] ? futex_wait_setup+0x281/0x410 [ 35.365011] ? find_held_lock+0x36/0x1c0 [ 35.369089] ? futex_wake+0x760/0x760 [ 35.372908] ? __sanitizer_cov_trace_switch+0x53/0x90 [ 35.378113] futex_wait+0x45b/0xa20 [ 35.381759] ? rcu_cleanup_dead_rnp+0x200/0x200 [ 35.386454] ? futex_wait_setup+0x410/0x410 [ 35.390816] ? __sanitizer_cov_trace_switch+0x53/0x90 [ 35.396020] ? __sanitizer_cov_trace_const_cmp1+0x1a/0x20 [ 35.401579] ? drop_futex_key_refs.isra.14+0x6d/0xe0 [ 35.406698] ? futex_wake+0x304/0x760 [ 35.410533] ? save_stack+0xa9/0xd0 [ 35.414174] ? __kasan_slab_free+0x11a/0x170 [ 35.418659] ? kasan_slab_free+0xe/0x10 [ 35.422785] ? kmem_cache_free+0x86/0x2d0 [ 35.426941] ? putname+0xf2/0x130 [ 35.430404] ? filename_lookup+0x397/0x510 [ 35.434652] do_futex+0x336/0x27d0 [ 35.438203] ? kasan_check_read+0x11/0x20 [ 35.442362] ? do_raw_spin_unlock+0xa7/0x2f0 [ 35.446786] ? do_raw_spin_trylock+0x1c0/0x1c0 [ 35.451382] ? kasan_check_write+0x14/0x20 [ 35.455631] ? do_raw_spin_lock+0xc1/0x200 [ 35.459877] ? exit_robust_list+0x290/0x290 [ 35.464209] ? _raw_spin_unlock_irqrestore+0x63/0xc0 [ 35.469331] ? debug_check_no_obj_freed+0x30b/0x595 [ 35.474356] ? path_lookupat.isra.45+0x381/0xc00 [ 35.479120] ? kasan_check_read+0x11/0x20 [ 35.483281] ? rcu_is_watching+0x8c/0x150 [ 35.487441] ? rcu_pm_notify+0xc0/0xc0 [ 35.491362] ? putname+0xf2/0x130 [ 35.494829] ? putname+0xf2/0x130 [ 35.498304] ? rcu_read_lock_sched_held+0x108/0x120 [ 35.503334] ? kmem_cache_free+0x25c/0x2d0 [ 35.507583] ? putname+0xf7/0x130 [ 35.511048] ? filename_lookup+0x39c/0x510 [ 35.515290] ? nd_jump_link+0x1d0/0x1d0 [ 35.519283] ? mpi_free.cold.1+0x19/0x19 [ 35.523366] ? __sanitizer_cov_trace_const_cmp4+0x16/0x20 [ 35.528912] ? getname_flags+0x26e/0x5a0 [ 35.532989] ? user_path_at_empty+0x40/0x50 [ 35.537331] ? __sanitizer_cov_trace_const_cmp4+0x16/0x20 [ 35.542888] ? do_linkat+0x3ec/0xaa0 [ 35.546620] __x64_sys_futex+0x472/0x6a0 [ 35.550695] ? do_futex+0x27d0/0x27d0 [ 35.554518] ? filp_open+0x80/0x80 [ 35.558073] ? do_syscall_64+0x9a/0x820 [ 35.562063] do_syscall_64+0x1b9/0x820 [ 35.565964] ? finish_task_switch+0x1d3/0x870 [ 35.570493] ? syscall_return_slowpath+0x5e0/0x5e0 [ 35.575437] ? syscall_return_slowpath+0x31d/0x5e0 [ 35.580488] ? entry_SYSCALL_64_after_hwframe+0x59/0xbe [ 35.585868] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 35.590732] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 35.595935] RIP: 0033:0x4468a9 [ 35.599289] Code: e8 0c e8 ff ff 48 83 c4 18 c3 0f 1f 80 00 00 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 7b 08 fc ff c3 66 2e 0f 1f 84 00 00 00 00 [ 35.618207] RSP: 002b:00007f34d3e78da8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca [ 35.625931] RAX: ffffffffffffffda RBX: 00000000006dbc88 RCX: 00000000004468a9 [ 35.633260] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 00000000006dbc88 [ 35.640541] RBP: 00000000006dbc80 R08: 0000000000000000 R09: 0000000000000000 [ 35.647903] R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006dbc8c [ 35.655185] R13: 0030656c69662f2e R14: 6c75662f7665642f R15: 00000000006dbd6c [ 35.663125] Dumping ftrace buffer: [ 35.666673] (ftrace buffer empty) [ 35.670376] Kernel Offset: disabled [ 35.674118] Rebooting in 86400 seconds..