[....] Starting enhanced syslogd: rsyslogd[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 22.049229] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 27.166121] random: sshd: uninitialized urandom read (32 bytes read) [ 27.366695] random: sshd: uninitialized urandom read (32 bytes read) [ 27.899850] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.30' (ECDSA) to the list of known hosts. [ 33.542393] urandom_read: 1 callbacks suppressed [ 33.542399] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program executing program executing program executing program executing program executing program executing program [ 33.653041] hrtimer: interrupt took 89644 ns [ 33.819585] ================================================================== [ 33.827206] BUG: KASAN: use-after-free in finish_task_switch+0x544/0x870 [ 33.834094] Read of size 8 at addr ffff8801c3d48058 by task syz-executor531/4426 [ 33.841609] [ 33.843220] CPU: 1 PID: 4426 Comm: syz-executor531 Not tainted 4.18.0-next-20180814+ #38 [ 33.851423] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 33.860767] Call Trace: [ 33.863338] dump_stack+0x1c9/0x2b4 [ 33.866949] ? dump_stack_print_info.cold.2+0x52/0x52 [ 33.872123] ? printk+0xa7/0xcf [ 33.875384] ? kmsg_dump_rewind_nolock+0xe4/0xe4 [ 33.880123] ? finish_task_switch+0x544/0x870 [ 33.884610] print_address_description+0x6c/0x20b [ 33.889437] ? finish_task_switch+0x544/0x870 [ 33.893916] kasan_report.cold.7+0x242/0x30d [ 33.898307] __asan_report_load8_noabort+0x14/0x20 [ 33.903220] finish_task_switch+0x544/0x870 [ 33.907522] ? __switch_to_asm+0x34/0x70 [ 33.911576] ? preempt_notifier_register+0x200/0x200 [ 33.916665] ? __switch_to_asm+0x34/0x70 [ 33.920718] ? __switch_to_asm+0x34/0x70 [ 33.924763] ? __switch_to_asm+0x40/0x70 [ 33.928809] ? __switch_to_asm+0x34/0x70 [ 33.932856] ? __switch_to_asm+0x40/0x70 [ 33.936897] ? __switch_to_asm+0x34/0x70 [ 33.940941] ? __switch_to_asm+0x40/0x70 [ 33.944994] ? __switch_to_asm+0x34/0x70 [ 33.949058] ? __switch_to_asm+0x34/0x70 [ 33.953102] ? __switch_to_asm+0x40/0x70 [ 33.957151] ? __switch_to_asm+0x34/0x70 [ 33.961274] ? __switch_to_asm+0x40/0x70 [ 33.965321] ? __switch_to_asm+0x34/0x70 [ 33.969365] ? __switch_to_asm+0x40/0x70 [ 33.973411] __schedule+0x884/0x1df0 [ 33.977113] ? __sched_text_start+0x8/0x8 [ 33.981246] ? graph_lock+0x170/0x170 [ 33.985032] ? plist_check_list+0xa0/0xa0 [ 33.989182] schedule+0xfb/0x450 [ 33.992529] ? lock_downgrade+0x8f0/0x8f0 [ 33.996670] ? __schedule+0x1df0/0x1df0 [ 34.000855] ? print_usage_bug+0xc0/0xc0 [ 34.004903] ? kasan_check_read+0x11/0x20 [ 34.009057] ? do_raw_spin_unlock+0xa7/0x2f0 [ 34.013452] ? do_raw_spin_trylock+0x1c0/0x1c0 [ 34.018025] ? lock_acquire+0x1e4/0x4f0 [ 34.021984] ? graph_lock+0x170/0x170 [ 34.025773] futex_wait_queue_me+0x3f9/0x840 [ 34.030160] ? __lock_acquire+0x7fc/0x5020 [ 34.034376] ? refill_pi_state_cache.part.8+0x320/0x320 [ 34.039722] ? kasan_check_write+0x14/0x20 [ 34.043940] ? do_raw_spin_lock+0xc1/0x200 [ 34.048170] ? __sanitizer_cov_trace_const_cmp4+0x16/0x20 [ 34.053688] ? get_futex_value_locked+0xcb/0xf0 [ 34.058338] ? __sanitizer_cov_trace_cmp4+0x16/0x20 [ 34.063336] ? futex_wait_setup+0x281/0x410 [ 34.067642] ? futex_wake+0x760/0x760 [ 34.071427] ? mark_held_locks+0x160/0x160 [ 34.075648] futex_wait+0x45b/0xa20 [ 34.079273] ? futex_wait_setup+0x410/0x410 [ 34.083707] ? handle_dr+0x8c0/0x8c0 [ 34.087409] ? __sanitizer_cov_trace_const_cmp4+0x16/0x20 [ 34.092941] ? __perf_event_task_sched_in+0x24f/0xbb0 [ 34.098138] ? __sanitizer_cov_trace_const_cmp1+0x1a/0x20 [ 34.103669] ? vmx_sched_in+0xe0/0x560 [ 34.107544] do_futex+0x336/0x27d0 [ 34.111069] ? kvm_arch_dev_ioctl+0x610/0x610 [ 34.115562] ? trace_hardirqs_off_caller+0x2b0/0x2b0 [ 34.120652] ? exit_robust_list+0x290/0x290 [ 34.124957] ? finish_task_switch+0x50d/0x870 [ 34.129435] ? __switch_to_asm+0x34/0x70 [ 34.133483] ? preempt_notifier_register+0x200/0x200 [ 34.138582] ? __switch_to_asm+0x34/0x70 [ 34.142632] ? __switch_to_asm+0x34/0x70 [ 34.146691] ? __switch_to_asm+0x40/0x70 [ 34.150734] ? __switch_to_asm+0x34/0x70 [ 34.154782] ? __switch_to_asm+0x40/0x70 [ 34.158830] ? __switch_to_asm+0x40/0x70 [ 34.162873] ? __switch_to_asm+0x34/0x70 [ 34.166915] ? __switch_to_asm+0x34/0x70 [ 34.171010] ? __switch_to_asm+0x40/0x70 [ 34.175060] ? __switch_to_asm+0x34/0x70 [ 34.179103] ? __switch_to_asm+0x40/0x70 [ 34.183185] ? __switch_to_asm+0x34/0x70 [ 34.187296] ? __switch_to_asm+0x40/0x70 [ 34.191403] ? __schedule+0x884/0x1df0 [ 34.195288] ? __sched_text_start+0x8/0x8 [ 34.199423] ? __fget+0x4d5/0x740 [ 34.202864] ? ksys_dup3+0x690/0x690 [ 34.206563] ? initcall_blacklisted+0x9a/0x1e0 [ 34.211134] ? _raw_spin_unlock_irqrestore+0x63/0xc0 [ 34.216331] ? kvm_uevent_notify_change.part.32+0x440/0x440 [ 34.222027] ? __sanitizer_cov_trace_const_cmp4+0x16/0x20 [ 34.227618] ? do_vfs_ioctl+0x201/0x1720 [ 34.231672] ? schedule+0xfb/0x450 [ 34.235221] ? ioctl_preallocate+0x300/0x300 [ 34.239616] ? __schedule+0x1df0/0x1df0 [ 34.243576] ? exit_to_usermode_loop+0x8c/0x380 [ 34.248234] ? exit_to_usermode_loop+0x8c/0x380 [ 34.252889] ? trace_hardirqs_off+0xb8/0x2b0 [ 34.257279] ? kmem_cache_free+0x246/0x280 [ 34.261500] __x64_sys_futex+0x472/0x6a0 [ 34.265552] ? do_futex+0x27d0/0x27d0 [ 34.269350] ? trace_hardirqs_on+0xbd/0x2c0 [ 34.273655] ? exit_to_usermode_loop+0x1f4/0x380 [ 34.278465] ? entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 34.283831] ? trace_hardirqs_off_caller+0x2b0/0x2b0 [ 34.288918] ? ksys_ioctl+0x81/0xd0 [ 34.292547] do_syscall_64+0x1b9/0x820 [ 34.296415] ? entry_SYSCALL_64_after_hwframe+0x3e/0xbe [ 34.301762] ? syscall_return_slowpath+0x5e0/0x5e0 [ 34.306675] ? trace_hardirqs_on_caller+0x2b0/0x2b0 [ 34.311674] ? prepare_exit_to_usermode+0x3b0/0x3b0 [ 34.316675] ? recalc_sigpending_tsk+0x180/0x180 [ 34.321414] ? kasan_check_write+0x14/0x20 [ 34.325634] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 34.330473] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 34.335659] RIP: 0033:0x446549 [ 34.338835] 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 [ 34.357817] RSP: 002b:00007fe4c7456da8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca [ 34.365715] RAX: ffffffffffffffda RBX: 00000000006dbc58 RCX: 0000000000446549 [ 34.372974] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 00000000006dbc58 [ 34.380242] RBP: 00000000006dbc50 R08: 0000000000000000 R09: 0000000000000000 [ 34.387504] R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006dbc5c [ 34.394769] R13: 6d766b2f7665642f R14: 00007fe4c74579c0 R15: 0000000000000001 [ 34.402053] [ 34.403746] Allocated by task 4426: [ 34.407443] save_stack+0x43/0xd0 [ 34.410898] kasan_kmalloc+0xc4/0xe0 [ 34.414647] kasan_slab_alloc+0x12/0x20 [ 34.418617] kmem_cache_alloc+0x12e/0x710 [ 34.422750] vmx_create_vcpu+0xcf/0x28b0 [ 34.426791] kvm_arch_vcpu_create+0xe5/0x220 [ 34.431181] kvm_vm_ioctl+0x488/0x1d80 [ 34.435063] do_vfs_ioctl+0x1de/0x1720 [ 34.438948] ksys_ioctl+0xa9/0xd0 [ 34.442383] __x64_sys_ioctl+0x73/0xb0 [ 34.446268] do_syscall_64+0x1b9/0x820 [ 34.450142] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 34.455308] [ 34.456932] Freed by task 4411: [ 34.460210] save_stack+0x43/0xd0 [ 34.463649] __kasan_slab_free+0x11a/0x170 [ 34.467864] kasan_slab_free+0xe/0x10 [ 34.471645] kmem_cache_free+0x86/0x280 [ 34.475607] vmx_free_vcpu+0x26b/0x300 [ 34.479485] kvm_arch_destroy_vm+0x365/0x7c0 [ 34.483891] kvm_put_kvm+0x73f/0x1060 [ 34.487689] kvm_vcpu_release+0x7b/0xa0 [ 34.491647] __fput+0x376/0x8a0 [ 34.494925] ____fput+0x15/0x20 [ 34.498204] task_work_run+0x1e8/0x2a0 [ 34.502078] exit_to_usermode_loop+0x318/0x380 [ 34.506657] do_syscall_64+0x6be/0x820 [ 34.510544] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 34.515709] [ 34.517338] The buggy address belongs to the object at ffff8801c3d48040 [ 34.517338] which belongs to the cache kvm_vcpu of size 23808 [ 34.529898] The buggy address is located 24 bytes inside of [ 34.529898] 23808-byte region [ffff8801c3d48040, ffff8801c3d4dd40) [ 34.541842] The buggy address belongs to the page: [ 34.546762] page:ffffea00070f5200 count:1 mapcount:0 mapping:ffff8801d53e4900 index:0x0 compound_mapcount: 0 [ 34.556718] flags: 0x2fffc0000008100(slab|head) [ 34.561369] raw: 02fffc0000008100 ffff8801d53e1548 ffffea0007165608 ffff8801d53e4900 [ 34.569233] raw: 0000000000000000 ffff8801c3d48040 0000000100000001 0000000000000000 [ 34.577090] page dumped because: kasan: bad access detected [ 34.582796] [ 34.584405] Memory state around the buggy address: [ 34.589317] ffff8801c3d47f00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 34.596658] ffff8801c3d47f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 34.604001] >ffff8801c3d48000: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb [ 34.611349] ^ [ 34.617567] ffff8801c3d48080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 34.624911] ffff8801c3d48100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 34.632264] ================================================================== [ 34.639622] Disabling lock debugging due to kernel taint [ 34.645242] Kernel panic - not syncing: panic_on_warn set ... [ 34.645242] [ 34.652597] CPU: 1 PID: 4426 Comm: syz-executor531 Tainted: G B 4.18.0-next-20180814+ #38 [ 34.662197] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 34.671529] Call Trace: [ 34.674106] dump_stack+0x1c9/0x2b4 [ 34.677718] ? dump_stack_print_info.cold.2+0x52/0x52 [ 34.682971] ? trace_hardirqs_on_thunk+0x1a/0x1c [ 34.687730] panic+0x238/0x4e7 [ 34.691023] ? add_taint.cold.5+0x16/0x16 [ 34.695162] ? trace_hardirqs_on+0xb4/0x2c0 [ 34.699464] ? trace_hardirqs_on+0x9a/0x2c0 [ 34.703781] ? finish_task_switch+0x544/0x870 [ 34.708261] kasan_end_report+0x47/0x4f [ 34.712218] kasan_report.cold.7+0x76/0x30d [ 34.716523] __asan_report_load8_noabort+0x14/0x20 [ 34.721585] finish_task_switch+0x544/0x870 [ 34.725887] ? __switch_to_asm+0x34/0x70 [ 34.729954] ? preempt_notifier_register+0x200/0x200 [ 34.735033] ? __switch_to_asm+0x34/0x70 [ 34.739076] ? __switch_to_asm+0x34/0x70 [ 34.743136] ? __switch_to_asm+0x40/0x70 [ 34.747185] ? __switch_to_asm+0x34/0x70 [ 34.751225] ? __switch_to_asm+0x40/0x70 [ 34.755267] ? __switch_to_asm+0x34/0x70 [ 34.759308] ? __switch_to_asm+0x40/0x70 [ 34.763354] ? __switch_to_asm+0x34/0x70 [ 34.767397] ? __switch_to_asm+0x34/0x70 [ 34.771453] ? __switch_to_asm+0x40/0x70 [ 34.775511] ? __switch_to_asm+0x34/0x70 [ 34.779570] ? __switch_to_asm+0x40/0x70 [ 34.783614] ? __switch_to_asm+0x34/0x70 [ 34.787657] ? __switch_to_asm+0x40/0x70 [ 34.791762] __schedule+0x884/0x1df0 [ 34.795475] ? __sched_text_start+0x8/0x8 [ 34.799609] ? graph_lock+0x170/0x170 [ 34.803478] ? plist_check_list+0xa0/0xa0 [ 34.807630] schedule+0xfb/0x450 [ 34.810987] ? lock_downgrade+0x8f0/0x8f0 [ 34.815114] ? __schedule+0x1df0/0x1df0 [ 34.819088] ? print_usage_bug+0xc0/0xc0 [ 34.823133] ? kasan_check_read+0x11/0x20 [ 34.827368] ? do_raw_spin_unlock+0xa7/0x2f0 [ 34.831762] ? do_raw_spin_trylock+0x1c0/0x1c0 [ 34.836326] ? lock_acquire+0x1e4/0x4f0 [ 34.840280] ? graph_lock+0x170/0x170 [ 34.844086] futex_wait_queue_me+0x3f9/0x840 [ 34.848489] ? __lock_acquire+0x7fc/0x5020 [ 34.852710] ? refill_pi_state_cache.part.8+0x320/0x320 [ 34.858054] ? kasan_check_write+0x14/0x20 [ 34.862269] ? do_raw_spin_lock+0xc1/0x200 [ 34.866492] ? __sanitizer_cov_trace_const_cmp4+0x16/0x20 [ 34.872069] ? get_futex_value_locked+0xcb/0xf0 [ 34.876730] ? __sanitizer_cov_trace_cmp4+0x16/0x20 [ 34.881728] ? futex_wait_setup+0x281/0x410 [ 34.886033] ? futex_wake+0x760/0x760 [ 34.889827] ? mark_held_locks+0x160/0x160 [ 34.894044] futex_wait+0x45b/0xa20 [ 34.897706] ? futex_wait_setup+0x410/0x410 [ 34.902027] ? handle_dr+0x8c0/0x8c0 [ 34.905723] ? __sanitizer_cov_trace_const_cmp4+0x16/0x20 [ 34.911240] ? __perf_event_task_sched_in+0x24f/0xbb0 [ 34.916417] ? __sanitizer_cov_trace_const_cmp1+0x1a/0x20 [ 34.922001] ? vmx_sched_in+0xe0/0x560 [ 34.925885] do_futex+0x336/0x27d0 [ 34.929409] ? kvm_arch_dev_ioctl+0x610/0x610 [ 34.933888] ? trace_hardirqs_off_caller+0x2b0/0x2b0 [ 34.939030] ? exit_robust_list+0x290/0x290 [ 34.943343] ? finish_task_switch+0x50d/0x870 [ 34.947823] ? __switch_to_asm+0x34/0x70 [ 34.951879] ? preempt_notifier_register+0x200/0x200 [ 34.956976] ? __switch_to_asm+0x34/0x70 [ 34.961117] ? __switch_to_asm+0x34/0x70 [ 34.965169] ? __switch_to_asm+0x40/0x70 [ 34.969208] ? __switch_to_asm+0x34/0x70 [ 34.973259] ? __switch_to_asm+0x40/0x70 [ 34.977297] ? __switch_to_asm+0x40/0x70 [ 34.981340] ? __switch_to_asm+0x34/0x70 [ 34.985399] ? __switch_to_asm+0x34/0x70 [ 34.989444] ? __switch_to_asm+0x40/0x70 [ 34.993492] ? __switch_to_asm+0x34/0x70 [ 34.997545] ? __switch_to_asm+0x40/0x70 [ 35.001593] ? __switch_to_asm+0x34/0x70 [ 35.005634] ? __switch_to_asm+0x40/0x70 [ 35.009691] ? __schedule+0x884/0x1df0 [ 35.013670] ? __sched_text_start+0x8/0x8 [ 35.017800] ? __fget+0x4d5/0x740 [ 35.021243] ? ksys_dup3+0x690/0x690 [ 35.024941] ? initcall_blacklisted+0x9a/0x1e0 [ 35.029514] ? _raw_spin_unlock_irqrestore+0x63/0xc0 [ 35.034604] ? kvm_uevent_notify_change.part.32+0x440/0x440 [ 35.040648] ? __sanitizer_cov_trace_const_cmp4+0x16/0x20 [ 35.046170] ? do_vfs_ioctl+0x201/0x1720 [ 35.050215] ? schedule+0xfb/0x450 [ 35.053736] ? ioctl_preallocate+0x300/0x300 [ 35.058129] ? __schedule+0x1df0/0x1df0 [ 35.062163] ? exit_to_usermode_loop+0x8c/0x380 [ 35.066821] ? exit_to_usermode_loop+0x8c/0x380 [ 35.071581] ? trace_hardirqs_off+0xb8/0x2b0 [ 35.075971] ? kmem_cache_free+0x246/0x280 [ 35.080194] __x64_sys_futex+0x472/0x6a0 [ 35.084240] ? do_futex+0x27d0/0x27d0 [ 35.088020] ? trace_hardirqs_on+0xbd/0x2c0 [ 35.092322] ? exit_to_usermode_loop+0x1f4/0x380 [ 35.097059] ? entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 35.102405] ? trace_hardirqs_off_caller+0x2b0/0x2b0 [ 35.107495] ? ksys_ioctl+0x81/0xd0 [ 35.111105] do_syscall_64+0x1b9/0x820 [ 35.114978] ? entry_SYSCALL_64_after_hwframe+0x3e/0xbe [ 35.120324] ? syscall_return_slowpath+0x5e0/0x5e0 [ 35.125246] ? trace_hardirqs_on_caller+0x2b0/0x2b0 [ 35.130241] ? prepare_exit_to_usermode+0x3b0/0x3b0 [ 35.135249] ? recalc_sigpending_tsk+0x180/0x180 [ 35.139994] ? kasan_check_write+0x14/0x20 [ 35.144220] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 35.149053] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 35.154236] RIP: 0033:0x446549 [ 35.157463] 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 [ 35.176367] RSP: 002b:00007fe4c7456da8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca [ 35.184060] RAX: ffffffffffffffda RBX: 00000000006dbc58 RCX: 0000000000446549 [ 35.191319] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 00000000006dbc58 [ 35.198570] RBP: 00000000006dbc50 R08: 0000000000000000 R09: 0000000000000000 [ 35.205818] R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006dbc5c [ 35.213087] R13: 6d766b2f7665642f R14: 00007fe4c74579c0 R15: 0000000000000001 [ 35.220785] Dumping ftrace buffer: [ 35.224307] (ftrace buffer empty) [ 35.227997] Kernel Offset: disabled [ 35.231606] Rebooting in 86400 seconds..