Message-ID: <000000000000598cfe0573661657@google.com>
Date:   Tue, 14 Aug 2018 07:33:02 -0700
From:   syzbot <syzbot+1ff78ee6b7dd52919ab9@...kaller.appspotmail.com>
To:     hpa@...or.com, kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
        mingo@...hat.com, pbonzini@...hat.com, rkrcmar@...hat.com,
        syzkaller-bugs@...glegroups.com, tglx@...utronix.de, x86@...nel.org
Subject: KASAN: use-after-free Read in vmx_vcpu_load

Hello,

syzbot found the following crash on:

HEAD commit:    1c2f2531cf8b Add linux-next specific files for 20180809
git tree:       linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=10129c74400000
kernel config:  https://syzkaller.appspot.com/x/.config?x=44657afb75515c8b
dashboard link: https://syzkaller.appspot.com/bug?extid=1ff78ee6b7dd52919ab9
compiler:       gcc (GCC) 8.0.1 20180413 (experimental)

Unfortunately, I don't have any reproducer for this crash yet.

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+1ff78ee6b7dd52919ab9@...kaller.appspotmail.com

RDX: 0000000000000000 RSI: 0000000000000000 RDI: 00000000009300a8
RBP: 00000000009300a0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000009300ac
R13: 00007fff7398e49f R14: 00007f51b2d9f9c0 R15: 0000000000000000
==================================================================
BUG: KASAN: use-after-free in vmx_vcpu_load+0xf78/0xfe0  
arch/x86/kvm/vmx.c:2929
Read of size 8 at addr ffff88019a46e5e0 by task syz-executor7/17308

CPU: 1 PID: 17308 Comm: syz-executor7 Not tainted 4.18.0-rc8-next-20180809+  
#35
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+0x1c9/0x2b4 lib/dump_stack.c:113
  print_address_description+0x6c/0x20b mm/kasan/report.c:256
  kasan_report_error mm/kasan/report.c:354 [inline]
  kasan_report.cold.7+0x242/0x30d mm/kasan/report.c:412
  __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:433
  vmx_vcpu_load+0xf78/0xfe0 arch/x86/kvm/vmx.c:2929
  kvm_arch_vcpu_load+0x22b/0x940 arch/x86/kvm/x86.c:3081
  kvm_sched_in+0x82/0xa0 arch/x86/kvm/../../../virt/kvm/kvm_main.c:3975
  __fire_sched_in_preempt_notifiers kernel/sched/core.c:2481 [inline]
  fire_sched_in_preempt_notifiers kernel/sched/core.c:2487 [inline]
  finish_task_switch+0x50d/0x870 kernel/sched/core.c:2679
  context_switch kernel/sched/core.c:2826 [inline]
  __schedule+0x884/0x1ec0 kernel/sched/core.c:3471
  schedule+0xfb/0x450 kernel/sched/core.c:3515
  freezable_schedule include/linux/freezer.h:172 [inline]
  futex_wait_queue_me+0x3f9/0x840 kernel/futex.c:2530
  futex_wait+0x45b/0xa20 kernel/futex.c:2645
  do_futex+0x336/0x27d0 kernel/futex.c:3527
  __do_sys_futex kernel/futex.c:3587 [inline]
  __se_sys_futex kernel/futex.c:3555 [inline]
  __x64_sys_futex+0x472/0x6a0 kernel/futex.c:3555
  do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
  entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x457089
Code: fd 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 cb b4 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f51b2d9ecf8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: ffffffffffffffda RBX: 00000000009300a8 RCX: 0000000000457089
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 00000000009300a8
RBP: 00000000009300a0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000009300ac
R13: 00007fff7398e49f R14: 00007f51b2d9f9c0 R15: 0000000000000000

Allocated by task 17308:
  save_stack+0x43/0xd0 mm/kasan/kasan.c:448
  set_track mm/kasan/kasan.c:460 [inline]
  kasan_kmalloc+0xc4/0xe0 mm/kasan/kasan.c:553
  kasan_slab_alloc+0x12/0x20 mm/kasan/kasan.c:490
  kmem_cache_alloc+0x12e/0x760 mm/slab.c:3554
  kmem_cache_zalloc include/linux/slab.h:697 [inline]
  vmx_create_vcpu+0xcf/0x28b0 arch/x86/kvm/vmx.c:10682
  kvm_arch_vcpu_create+0xe5/0x220 arch/x86/kvm/x86.c:8401
  kvm_vm_ioctl_create_vcpu arch/x86/kvm/../../../virt/kvm/kvm_main.c:2476  
[inline]
  kvm_vm_ioctl+0x488/0x1d80 arch/x86/kvm/../../../virt/kvm/kvm_main.c:2977
  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 17301:
  save_stack+0x43/0xd0 mm/kasan/kasan.c:448
  set_track mm/kasan/kasan.c:460 [inline]
  __kasan_slab_free+0x11a/0x170 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+0x86/0x2d0 mm/slab.c:3756
  vmx_free_vcpu+0x26b/0x300 arch/x86/kvm/vmx.c:10676
  kvm_arch_vcpu_free arch/x86/kvm/x86.c:8387 [inline]
  kvm_free_vcpus arch/x86/kvm/x86.c:8836 [inline]
  kvm_arch_destroy_vm+0x365/0x7c0 arch/x86/kvm/x86.c:8933
  kvm_destroy_vm arch/x86/kvm/../../../virt/kvm/kvm_main.c:752 [inline]
  kvm_put_kvm+0x73f/0x1060 arch/x86/kvm/../../../virt/kvm/kvm_main.c:773
  kvm_vcpu_release+0x7b/0xa0 arch/x86/kvm/../../../virt/kvm/kvm_main.c:2407
  __fput+0x376/0x8a0 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 ffff88019a468e00
  which belongs to the cache kvm_vcpu of size 23808
The buggy address is located 22496 bytes inside of
  23808-byte region [ffff88019a468e00, ffff88019a46eb00)
The buggy address belongs to the page:
page:ffffea0006691a00 count:1 mapcount:0 mapping:ffff8801d9fed3c0 index:0x0  
compound_mapcount: 0
flags: 0x2fffc0000008100(slab|head)
raw: 02fffc0000008100 ffffea0006bd0c08 ffffea0006432c08 ffff8801d9fed3c0
raw: 0000000000000000 ffff88019a468e00 0000000100000001 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
  ffff88019a46e480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
  ffff88019a46e500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> ffff88019a46e580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                        ^
  ffff88019a46e600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
  ffff88019a46e680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================


---
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