[....] 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[ 22.560687] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 24.145165] random: sshd: uninitialized urandom read (32 bytes read) [ 24.381949] random: sshd: uninitialized urandom read (32 bytes read) [ 24.938446] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.20' (ECDSA) to the list of known hosts. [ 30.703265] urandom_read: 1 callbacks suppressed [ 30.703272] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program executing program executing program executing program executing program executing program executing program [ 30.817746] hrtimer: interrupt took 35369 ns [ 30.831049] L1TF CPU bug present and SMT on, data leak possible. See CVE-2018-3646 and https://www.kernel.org/doc/html/latest/admin-guide/l1tf.html for details. [ 31.024341] ================================================================== [ 31.031874] BUG: KASAN: use-after-free in finish_task_switch+0x544/0x870 [ 31.038722] Read of size 8 at addr ffff8801c7b20058 by task syz-executor815/4696 [ 31.046258] [ 31.047901] CPU: 0 PID: 4696 Comm: syz-executor815 Not tainted 4.19.0-rc2+ #220 [ 31.055348] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 31.064704] Call Trace: [ 31.067305] dump_stack+0x1c9/0x2b4 [ 31.070948] ? dump_stack_print_info.cold.2+0x52/0x52 [ 31.076151] ? printk+0xa7/0xcf [ 31.079439] ? kmsg_dump_rewind_nolock+0xe4/0xe4 [ 31.084207] ? finish_task_switch+0x544/0x870 [ 31.088737] print_address_description+0x6c/0x20b [ 31.093589] ? finish_task_switch+0x544/0x870 [ 31.098593] kasan_report.cold.7+0x242/0x30d [ 31.103021] __asan_report_load8_noabort+0x14/0x20 [ 31.107967] finish_task_switch+0x544/0x870 [ 31.112297] ? __switch_to_asm+0x34/0x70 [ 31.116372] ? preempt_notifier_register+0x200/0x200 [ 31.121484] ? __switch_to_asm+0x34/0x70 [ 31.125553] ? __switch_to_asm+0x34/0x70 [ 31.129620] ? __switch_to_asm+0x40/0x70 [ 31.133691] ? __switch_to_asm+0x34/0x70 [ 31.137766] ? __switch_to_asm+0x40/0x70 [ 31.141835] ? __switch_to_asm+0x34/0x70 [ 31.145905] ? __switch_to_asm+0x40/0x70 [ 31.149971] ? __switch_to_asm+0x34/0x70 [ 31.154040] ? __switch_to_asm+0x34/0x70 [ 31.158124] ? __switch_to_asm+0x40/0x70 [ 31.162207] ? __switch_to_asm+0x34/0x70 [ 31.166273] ? __switch_to_asm+0x40/0x70 [ 31.170340] ? __switch_to_asm+0x34/0x70 [ 31.174407] ? __switch_to_asm+0x40/0x70 [ 31.178484] __schedule+0x884/0x1df0 [ 31.182223] ? __sched_text_start+0x8/0x8 [ 31.186392] ? graph_lock+0x170/0x170 [ 31.190204] ? plist_check_list+0xa0/0xa0 [ 31.194364] ? mark_held_locks+0x160/0x160 [ 31.198627] schedule+0xfb/0x450 [ 31.201994] ? lock_downgrade+0x8f0/0x8f0 [ 31.206146] ? __schedule+0x1df0/0x1df0 [ 31.210123] ? rcu_cleanup_dead_rnp+0x200/0x200 [ 31.214795] ? kasan_check_read+0x11/0x20 [ 31.218949] ? do_raw_spin_unlock+0xa7/0x2f0 [ 31.223380] ? do_raw_spin_trylock+0x1c0/0x1c0 [ 31.228238] ? lock_acquire+0x1e4/0x4f0 [ 31.232226] futex_wait_queue_me+0x3f9/0x840 [ 31.236639] ? refill_pi_state_cache.part.8+0x320/0x320 [ 31.242005] ? kasan_check_write+0x14/0x20 [ 31.246240] ? do_raw_spin_lock+0xc1/0x200 [ 31.250478] ? __sanitizer_cov_trace_const_cmp4+0x16/0x20 [ 31.256016] ? get_futex_value_locked+0xcb/0xf0 [ 31.260689] ? __sanitizer_cov_trace_cmp4+0x16/0x20 [ 31.265712] ? futex_wait_setup+0x281/0x410 [ 31.270066] ? futex_wake+0x760/0x760 [ 31.273880] ? __lock_acquire+0x7fc/0x5020 [ 31.278122] futex_wait+0x45b/0xa20 [ 31.281762] ? futex_wait_setup+0x410/0x410 [ 31.286096] ? __sanitizer_cov_trace_switch+0x53/0x90 [ 31.291289] ? drop_futex_key_refs.isra.14+0x6d/0xe0 [ 31.296392] ? futex_wake+0x304/0x760 [ 31.300198] ? __mutex_unlock_slowpath+0x197/0x8c0 [ 31.305135] ? wait_for_completion+0x8d0/0x8d0 [ 31.309731] ? rcu_pm_notify+0xc0/0xc0 [ 31.313644] do_futex+0x336/0x27d0 [ 31.317194] ? kfree+0x1d7/0x210 [ 31.320567] ? kvm_vcpu_ioctl+0x2ba/0x1280 [ 31.324815] ? exit_robust_list+0x290/0x290 [ 31.329160] ? lock_downgrade+0x8f0/0x8f0 [ 31.333323] ? kasan_check_read+0x11/0x20 [ 31.337474] ? rcu_is_watching+0x8c/0x150 [ 31.341623] ? rcu_cleanup_dead_rnp+0x200/0x200 [ 31.346300] ? __fget+0x4d5/0x740 [ 31.349760] ? ksys_dup3+0x690/0x690 [ 31.353478] ? kasan_check_write+0x14/0x20 [ 31.357732] ? _raw_spin_unlock_irqrestore+0x63/0xc0 [ 31.362850] ? kvm_uevent_notify_change.part.32+0x440/0x440 [ 31.368569] ? __sanitizer_cov_trace_const_cmp4+0x16/0x20 [ 31.374116] ? do_vfs_ioctl+0x201/0x1720 [ 31.378183] ? rcu_is_watching+0x8c/0x150 [ 31.382331] ? trace_hardirqs_on+0xbd/0x2c0 [ 31.386661] ? ioctl_preallocate+0x300/0x300 [ 31.391092] ? __fget_light+0x2f7/0x440 [ 31.395086] ? fget_raw+0x20/0x20 [ 31.398572] ? putname+0xf2/0x130 [ 31.402033] ? rcu_read_lock_sched_held+0x108/0x120 [ 31.407079] ? kmem_cache_free+0x246/0x280 [ 31.411327] __x64_sys_futex+0x472/0x6a0 [ 31.415394] ? do_futex+0x27d0/0x27d0 [ 31.419195] ? trace_hardirqs_on+0xbd/0x2c0 [ 31.423519] ? __sanitizer_cov_trace_const_cmp1+0x1a/0x20 [ 31.429067] ? entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 31.434439] ? trace_hardirqs_off_caller+0x2b0/0x2b0 [ 31.439588] ? ksys_ioctl+0x81/0xd0 [ 31.443238] do_syscall_64+0x1b9/0x820 [ 31.447138] ? entry_SYSCALL_64_after_hwframe+0x3e/0xbe [ 31.452514] ? syscall_return_slowpath+0x5e0/0x5e0 [ 31.457448] ? trace_hardirqs_on_caller+0x2b0/0x2b0 [ 31.462488] ? prepare_exit_to_usermode+0x3b0/0x3b0 [ 31.467506] ? recalc_sigpending_tsk+0x180/0x180 [ 31.472291] ? kasan_check_write+0x14/0x20 [ 31.476533] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 31.481393] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 31.486587] RIP: 0033:0x4464d9 [ 31.489792] 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 [ 31.508704] RSP: 002b:00007fd07b576da8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca [ 31.516426] RAX: ffffffffffffffda RBX: 00000000006dbc58 RCX: 00000000004464d9 [ 31.523693] RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00000000006dbc58 [ 31.530969] RBP: 00000000006dbc50 R08: 0000000000000000 R09: 0000000000000000 [ 31.538242] R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006dbc5c [ 31.545513] R13: 6d766b2f7665642f R14: 00007fd07b5779c0 R15: 0000000000000003 [ 31.552804] [ 31.554439] Allocated by task 4698: [ 31.558095] save_stack+0x43/0xd0 [ 31.561563] kasan_kmalloc+0xc4/0xe0 [ 31.565279] kasan_slab_alloc+0x12/0x20 [ 31.569255] kmem_cache_alloc+0x12e/0x710 [ 31.573414] vmx_create_vcpu+0xcf/0x2830 [ 31.577475] kvm_arch_vcpu_create+0xe5/0x220 [ 31.581883] kvm_vm_ioctl+0x488/0x1d80 [ 31.585770] do_vfs_ioctl+0x1de/0x1720 [ 31.589657] ksys_ioctl+0xa9/0xd0 [ 31.593111] __x64_sys_ioctl+0x73/0xb0 [ 31.597002] do_syscall_64+0x1b9/0x820 [ 31.600888] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 31.606072] [ 31.607701] Freed by task 4668: [ 31.610982] save_stack+0x43/0xd0 [ 31.614433] __kasan_slab_free+0x11a/0x170 [ 31.618666] kasan_slab_free+0xe/0x10 [ 31.622465] kmem_cache_free+0x86/0x280 [ 31.626436] vmx_free_vcpu+0x26b/0x300 [ 31.630322] kvm_arch_destroy_vm+0x365/0x7c0 [ 31.634730] kvm_put_kvm+0x73f/0x1060 [ 31.638532] kvm_vcpu_release+0x7b/0xa0 [ 31.642505] __fput+0x38a/0xa40 [ 31.645788] ____fput+0x15/0x20 [ 31.649073] task_work_run+0x1e8/0x2a0 [ 31.652970] exit_to_usermode_loop+0x318/0x380 [ 31.657551] do_syscall_64+0x6be/0x820 [ 31.661442] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 31.666620] [ 31.668251] The buggy address belongs to the object at ffff8801c7b20040 [ 31.668251] which belongs to the cache kvm_vcpu of size 23872 [ 31.680832] The buggy address is located 24 bytes inside of [ 31.680832] 23872-byte region [ffff8801c7b20040, ffff8801c7b25d80) [ 31.692797] The buggy address belongs to the page: [ 31.697738] page:ffffea00071ec800 count:1 mapcount:0 mapping:ffff8801d523fb40 index:0x0 compound_mapcount: 0 [ 31.707721] flags: 0x2fffc0000008100(slab|head) [ 31.712400] raw: 02fffc0000008100 ffff8801d7395148 ffffea00071f7408 ffff8801d523fb40 [ 31.720290] raw: 0000000000000000 ffff8801c7b20040 0000000100000001 0000000000000000 [ 31.728163] page dumped because: kasan: bad access detected [ 31.733867] [ 31.735493] Memory state around the buggy address: [ 31.740423] ffff8801c7b1ff00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 31.747779] ffff8801c7b1ff80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 31.755139] >ffff8801c7b20000: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb [ 31.762490] ^ [ 31.768720] ffff8801c7b20080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb executing program [ 31.776095] ffff8801c7b20100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 31.783448] ================================================================== [ 31.790804] Disabling lock debugging due to kernel taint [ 31.796428] Kernel panic - not syncing: panic_on_warn set ... [ 31.796428] [ 31.803813] CPU: 0 PID: 4696 Comm: syz-executor815 Tainted: G B 4.19.0-rc2+ #220 [ 31.812650] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 31.822004] Call Trace: [ 31.824607] dump_stack+0x1c9/0x2b4 executing program [ 31.828242] ? dump_stack_print_info.cold.2+0x52/0x52 [ 31.833451] ? trace_hardirqs_on_thunk+0x1a/0x1c [ 31.838219] panic+0x238/0x4e7 [ 31.841409] ? add_taint.cold.5+0x16/0x16 [ 31.845556] ? trace_hardirqs_on+0xb4/0x2c0 [ 31.849873] ? trace_hardirqs_on+0x9a/0x2c0 [ 31.854195] ? finish_task_switch+0x544/0x870 [ 31.858688] kasan_end_report+0x47/0x4f [ 31.862663] kasan_report.cold.7+0x76/0x30d [ 31.867002] __asan_report_load8_noabort+0x14/0x20 [ 31.871941] finish_task_switch+0x544/0x870 [ 31.876265] ? __switch_to_asm+0x34/0x70 [ 31.880333] ? preempt_notifier_register+0x200/0x200 [ 31.885448] ? __switch_to_asm+0x34/0x70 [ 31.889522] ? __switch_to_asm+0x34/0x70 [ 31.893577] ? __switch_to_asm+0x40/0x70 [ 31.897638] ? __switch_to_asm+0x34/0x70 [ 31.901707] ? __switch_to_asm+0x40/0x70 [ 31.905780] ? __switch_to_asm+0x34/0x70 [ 31.909847] ? __switch_to_asm+0x40/0x70 [ 31.913926] ? __switch_to_asm+0x34/0x70 [ 31.917998] ? __switch_to_asm+0x34/0x70 [ 31.922071] ? __switch_to_asm+0x40/0x70 [ 31.926145] ? __switch_to_asm+0x34/0x70 [ 31.930215] ? __switch_to_asm+0x40/0x70 [ 31.934283] ? __switch_to_asm+0x34/0x70 [ 31.938342] ? __switch_to_asm+0x40/0x70 [ 31.942408] __schedule+0x884/0x1df0 [ 31.946128] ? __sched_text_start+0x8/0x8 [ 31.950278] ? graph_lock+0x170/0x170 [ 31.954091] ? plist_check_list+0xa0/0xa0 [ 31.958239] ? mark_held_locks+0x160/0x160 [ 31.962485] schedule+0xfb/0x450 [ 31.965856] ? lock_downgrade+0x8f0/0x8f0 [ 31.970003] ? __schedule+0x1df0/0x1df0 [ 31.973972] ? rcu_cleanup_dead_rnp+0x200/0x200 [ 31.978684] ? kasan_check_read+0x11/0x20 [ 31.982830] ? do_raw_spin_unlock+0xa7/0x2f0 [ 31.987237] ? do_raw_spin_trylock+0x1c0/0x1c0 [ 31.991815] ? lock_acquire+0x1e4/0x4f0 [ 31.995793] futex_wait_queue_me+0x3f9/0x840 [ 32.000200] ? refill_pi_state_cache.part.8+0x320/0x320 [ 32.005566] ? kasan_check_write+0x14/0x20 [ 32.009798] ? do_raw_spin_lock+0xc1/0x200 [ 32.014032] ? __sanitizer_cov_trace_const_cmp4+0x16/0x20 [ 32.019574] ? get_futex_value_locked+0xcb/0xf0 [ 32.024242] ? __sanitizer_cov_trace_cmp4+0x16/0x20 [ 32.029257] ? futex_wait_setup+0x281/0x410 [ 32.033579] ? futex_wake+0x760/0x760 [ 32.037382] ? __lock_acquire+0x7fc/0x5020 [ 32.041617] futex_wait+0x45b/0xa20 [ 32.045246] ? futex_wait_setup+0x410/0x410 [ 32.049746] ? __sanitizer_cov_trace_switch+0x53/0x90 [ 32.054934] ? drop_futex_key_refs.isra.14+0x6d/0xe0 [ 32.060081] ? futex_wake+0x304/0x760 [ 32.063887] ? __mutex_unlock_slowpath+0x197/0x8c0 [ 32.068840] ? wait_for_completion+0x8d0/0x8d0 [ 32.073449] ? rcu_pm_notify+0xc0/0xc0 [ 32.077342] do_futex+0x336/0x27d0 [ 32.080884] ? kfree+0x1d7/0x210 [ 32.084253] ? kvm_vcpu_ioctl+0x2ba/0x1280 [ 32.088492] ? exit_robust_list+0x290/0x290 [ 32.092816] ? lock_downgrade+0x8f0/0x8f0 [ 32.097414] ? kasan_check_read+0x11/0x20 [ 32.101567] ? rcu_is_watching+0x8c/0x150 [ 32.105715] ? rcu_cleanup_dead_rnp+0x200/0x200 [ 32.110407] ? __fget+0x4d5/0x740 [ 32.113864] ? ksys_dup3+0x690/0x690 [ 32.117578] ? kasan_check_write+0x14/0x20 [ 32.121814] ? _raw_spin_unlock_irqrestore+0x63/0xc0 [ 32.126917] ? kvm_uevent_notify_change.part.32+0x440/0x440 [ 32.132628] ? __sanitizer_cov_trace_const_cmp4+0x16/0x20 [ 32.138167] ? do_vfs_ioctl+0x201/0x1720 [ 32.142225] ? rcu_is_watching+0x8c/0x150 [ 32.146366] ? trace_hardirqs_on+0xbd/0x2c0 [ 32.150689] ? ioctl_preallocate+0x300/0x300 [ 32.155097] ? __fget_light+0x2f7/0x440 [ 32.159082] ? fget_raw+0x20/0x20 [ 32.162535] ? putname+0xf2/0x130 [ 32.165987] ? rcu_read_lock_sched_held+0x108/0x120 [ 32.171002] ? kmem_cache_free+0x246/0x280 [ 32.175238] __x64_sys_futex+0x472/0x6a0 [ 32.179300] ? do_futex+0x27d0/0x27d0 [ 32.183099] ? trace_hardirqs_on+0xbd/0x2c0 [ 32.187424] ? __sanitizer_cov_trace_const_cmp1+0x1a/0x20 [ 32.192958] ? entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 32.198324] ? trace_hardirqs_off_caller+0x2b0/0x2b0 [ 32.203424] ? ksys_ioctl+0x81/0xd0 [ 32.207062] do_syscall_64+0x1b9/0x820 [ 32.210952] ? entry_SYSCALL_64_after_hwframe+0x3e/0xbe [ 32.216315] ? syscall_return_slowpath+0x5e0/0x5e0 [ 32.221242] ? trace_hardirqs_on_caller+0x2b0/0x2b0 [ 32.226257] ? prepare_exit_to_usermode+0x3b0/0x3b0 [ 32.231270] ? recalc_sigpending_tsk+0x180/0x180 [ 32.236027] ? kasan_check_write+0x14/0x20 [ 32.240268] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 32.245118] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 32.250307] RIP: 0033:0x4464d9 [ 32.253501] 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 [ 32.272400] RSP: 002b:00007fd07b576da8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca [ 32.280106] RAX: ffffffffffffffda RBX: 00000000006dbc58 RCX: 00000000004464d9 [ 32.287367] RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00000000006dbc58 [ 32.294652] RBP: 00000000006dbc50 R08: 0000000000000000 R09: 0000000000000000 [ 32.301951] R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006dbc5c [ 32.309227] R13: 6d766b2f7665642f R14: 00007fd07b5779c0 R15: 0000000000000003 [ 32.316868] Dumping ftrace buffer: [ 32.320422] (ftrace buffer empty) [ 32.324124] Kernel Offset: disabled [ 32.327737] Rebooting in 86400 seconds..