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. ================================================================== BUG: KASAN: use-after-free in __fire_sched_in_preempt_notifiers kernel/sched/core.c:2486 [inline] BUG: KASAN: use-after-free in fire_sched_in_preempt_notifiers kernel/sched/core.c:2492 [inline] BUG: KASAN: use-after-free in finish_task_switch+0x78e/0x900 kernel/sched/core.c:2684 Read of size 8 at addr ffff8801a0918058 by task syz-executor3/7285 CPU: 0 PID: 7285 Comm: syz-executor3 Not tainted 4.19.0-rc4-next-20180921+ #77 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x1d3/0x2c4 lib/dump_stack.c:113 print_address_description.cold.8+0x9/0x1ff mm/kasan/report.c:256 kasan_report_error mm/kasan/report.c:354 [inline] kasan_report.cold.9+0x242/0x309 mm/kasan/report.c:412 __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:433 __fire_sched_in_preempt_notifiers kernel/sched/core.c:2486 [inline] fire_sched_in_preempt_notifiers kernel/sched/core.c:2492 [inline] finish_task_switch+0x78e/0x900 kernel/sched/core.c:2684 context_switch kernel/sched/core.c:2833 [inline] __schedule+0x874/0x1ed0 kernel/sched/core.c:3479 preempt_schedule_common+0x1f/0xd0 kernel/sched/core.c:3603 preempt_schedule+0x4d/0x60 kernel/sched/core.c:3629 ___preempt_schedule+0x16/0x18 __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:161 [inline] _raw_spin_unlock_irqrestore+0xbb/0xd0 kernel/locking/spinlock.c:184 try_to_wake_up+0x10a/0x12f0 kernel/sched/core.c:2060 wake_up_process kernel/sched/core.c:2128 [inline] wake_up_q+0xa4/0x100 kernel/sched/core.c:441 futex_wake+0x61f/0x760 kernel/futex.c:1556 do_futex+0x2e4/0x26d0 kernel/futex.c:3533 __do_sys_futex kernel/futex.c:3589 [inline] __se_sys_futex kernel/futex.c:3557 [inline] __x64_sys_futex+0x472/0x6a0 kernel/futex.c:3557 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x457679 Code: 1d b4 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 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 eb b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007fb7f70decf8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca RAX: ffffffffffffffda RBX: 000000000072bfa8 RCX: 0000000000457679 RDX: 0000000000000016 RSI: 0000000000000081 RDI: 000000000072bfac RBP: 000000000072bfa0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000072bfac R13: 00007ffe8841f7ef R14: 00007fb7f70df9c0 R15: 0000000000000001 Allocated by task 7283: save_stack+0x43/0xd0 mm/kasan/kasan.c:448 set_track mm/kasan/kasan.c:460 [inline] kasan_kmalloc+0xc7/0xe0 mm/kasan/kasan.c:553 kasan_slab_alloc+0x12/0x20 mm/kasan/kasan.c:490 kmem_cache_alloc+0x12e/0x730 mm/slab.c:3554 kmem_cache_zalloc include/linux/slab.h:731 [inline] vmx_create_vcpu+0xcf/0x25c0 arch/x86/kvm/vmx.c:10954 kvm_arch_vcpu_create+0xe5/0x220 arch/x86/kvm/x86.c:8452 kvm_vm_ioctl_create_vcpu arch/x86/kvm/../../../virt/kvm/kvm_main.c:2475 [inline] kvm_vm_ioctl+0x472/0x1d60 arch/x86/kvm/../../../virt/kvm/kvm_main.c:2976 vfs_ioctl fs/ioctl.c:46 [inline] file_ioctl fs/ioctl.c:501 [inline] do_vfs_ioctl+0x1de/0x1720 fs/ioctl.c:685 ksys_ioctl+0xa9/0xd0 fs/ioctl.c:702 __do_sys_ioctl fs/ioctl.c:709 [inline] __se_sys_ioctl fs/ioctl.c:707 [inline] __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:707 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe Freed by task 7282: save_stack+0x43/0xd0 mm/kasan/kasan.c:448 set_track mm/kasan/kasan.c:460 [inline] __kasan_slab_free+0x102/0x150 mm/kasan/kasan.c:521 kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528 __cache_free mm/slab.c:3498 [inline] kmem_cache_free+0x83/0x290 mm/slab.c:3756 vmx_free_vcpu+0x26b/0x300 arch/x86/kvm/vmx.c:10948 kvm_arch_vcpu_free arch/x86/kvm/x86.c:8438 [inline] kvm_free_vcpus arch/x86/kvm/x86.c:8888 [inline] kvm_arch_destroy_vm+0x365/0x7c0 arch/x86/kvm/x86.c:8985 kvm_destroy_vm arch/x86/kvm/../../../virt/kvm/kvm_main.c:751 [inline] kvm_put_kvm+0x6c8/0xff0 arch/x86/kvm/../../../virt/kvm/kvm_main.c:772 kvm_vcpu_release+0x7b/0xa0 arch/x86/kvm/../../../virt/kvm/kvm_main.c:2406 __fput+0x3bc/0xa70 fs/file_table.c:279 ____fput+0x15/0x20 fs/file_table.c:312 task_work_run+0x1e8/0x2a0 kernel/task_work.c:113 tracehook_notify_resume include/linux/tracehook.h:193 [inline] exit_to_usermode_loop+0x318/0x380 arch/x86/entry/common.c:166 prepare_exit_to_usermode arch/x86/entry/common.c:197 [inline] syscall_return_slowpath arch/x86/entry/common.c:268 [inline] do_syscall_64+0x6be/0x820 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe The buggy address belongs to the object at ffff8801a0918040 which belongs to the cache kvm_vcpu of size 23872 The buggy address is located 24 bytes inside of 23872-byte region [ffff8801a0918040, ffff8801a091dd80) The buggy address belongs to the page: page:ffffea0006824600 count:1 mapcount:0 mapping:ffff8801d59f8e00 index:0x0 compound_mapcount: 0 flags: 0x2fffc0000010200(slab|head) raw: 02fffc0000010200 ffff8801d59f2948 ffff8801d59f2948 ffff8801d59f8e00 raw: 0000000000000000 ffff8801a0918040 0000000100000001 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff8801a0917f00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff8801a0917f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff8801a0918000: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb ^ ffff8801a0918080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8801a0918100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================