Re: general protection fault in native_write_cr4

[Dmitry Vyukov]

On Wed, Dec 27, 2017 at 7:31 PM, Dmitry Vyukov <dvyukov@xxxxxxxxxx> wrote:
> On Tue, Dec 26, 2017 at 9:52 AM, Dmitry Vyukov <dvyukov@xxxxxxxxxx> wrote:
>> On Wed, Dec 20, 2017 at 8:54 AM, Wanpeng Li <kernellwp@xxxxxxxxx> wrote:
>>> 2017-12-20 15:49 GMT+08:00 syzbot
>>> <bot+ab09454bf4b7a7f8ce7e5e8d97e644d3314a0799@xxxxxxxxxxxxxxxxxxxxxxxxx>:
>>>> Hello,
>>>>
>>>> syzkaller hit the following crash on
>>>> f6f3732162b5ae3c771b9285a5a32d72b8586920
>>>> git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/master
>>>> compiler: gcc (GCC) 7.1.1 20170620
>>>> .config is attached
>>>> Raw console output is attached.
>>>> C reproducer is attached
>>>> syzkaller reproducer is attached. See https://goo.gl/kgGztJ
>>>> for information about syzkaller reproducers
>>>>
>>>>
>>>
>>> I will have a look again, you continue to run it in kvm guest, right?
>>
>>
>> Our test machines are GCE VMs, so yes, the kernel that catches GPF is
>> run as kvm guest.
>
> up
>
> one of top crashers with 50K crashes


This sets a new record of 130000 crashed machines on syzbot infrastructure:

https://syzkaller.appspot.com/bug?id=2bf7b7983c2398ec6f0c4c6c87cb50223e8873f8


>>>> kvm: KVM_SET_TSS_ADDR need to be called before entering vcpu
>>>> kasan: CONFIG_KASAN_INLINE enabled
>>>> kasan: GPF could be caused by NULL-ptr deref or user memory access
>>>> general protection fault: 0000 [#1] SMP KASAN
>>>> Dumping ftrace buffer:
>>>>    (ftrace buffer empty)
>>>> Modules linked in:
>>>> CPU: 1 PID: 3142 Comm: syzkaller429302 Not tainted 4.15.0-rc3+ #224
>>>> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
>>>> Google 01/01/2011
>>>> RIP: 0010:native_write_cr4+0x4/0x10 arch/x86/include/asm/special_insns.h:76
>>>> RSP: 0018:ffff8801ca6f75a0 EFLAGS: 00010093
>>>> RAX: ffff8801ca1c8700 RBX: 00000000001606e0 RCX: ffffffff811a2a92
>>>> RDX: 0000000000000000 RSI: 0000000000000000 RDI: 00000000001606e0
>>>> RBP: ffff8801ca6f75a0 R08: 1ffff100394dee0f R09: 0000000000000004
>>>> R10: ffff8801ca6f7510 R11: 0000000000000004 R12: 0000000000000093
>>>> R13: ffff8801ca1c8700 R14: ffff8801db514850 R15: ffff8801db514850
>>>> FS:  0000000001031880(0000) GS:ffff8801db500000(0000) knlGS:0000000000000000
>>>> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>>>> CR2: 0000000000000000 CR3: 0000000005e22006 CR4: 00000000001626e0
>>>> Call Trace:
>>>>  __write_cr4 arch/x86/include/asm/paravirt.h:76 [inline]
>>>>  __cr4_set arch/x86/include/asm/tlbflush.h:180 [inline]
>>>>  cr4_clear_bits arch/x86/include/asm/tlbflush.h:203 [inline]
>>>>  kvm_cpu_vmxoff arch/x86/kvm/vmx.c:3582 [inline]
>>>>  hardware_disable+0x34a/0x4b0 arch/x86/kvm/vmx.c:3588
>>>>  kvm_arch_hardware_disable+0x35/0xd0 arch/x86/kvm/x86.c:7982
>>>>  hardware_disable_nolock+0x30/0x40
>>>> arch/x86/kvm/../../../virt/kvm/kvm_main.c:3310
>>>>  on_each_cpu+0xca/0x1b0 kernel/smp.c:604
>>>>  hardware_disable_all_nolock+0x3e/0x50
>>>> arch/x86/kvm/../../../virt/kvm/kvm_main.c:3328
>>>>  hardware_disable_all arch/x86/kvm/../../../virt/kvm/kvm_main.c:3334
>>>> [inline]
>>>>  kvm_destroy_vm arch/x86/kvm/../../../virt/kvm/kvm_main.c:742 [inline]
>>>>  kvm_put_kvm+0x956/0xdf0 arch/x86/kvm/../../../virt/kvm/kvm_main.c:755
>>>>  kvm_vm_release+0x42/0x50 arch/x86/kvm/../../../virt/kvm/kvm_main.c:766
>>>>  __fput+0x327/0x7e0 fs/file_table.c:210
>>>>  ____fput+0x15/0x20 fs/file_table.c:244
>>>>  task_work_run+0x199/0x270 kernel/task_work.c:113
>>>>  exit_task_work include/linux/task_work.h:22 [inline]
>>>>  do_exit+0x9bb/0x1ad0 kernel/exit.c:865
>>>>  do_group_exit+0x149/0x400 kernel/exit.c:968
>>>>  SYSC_exit_group kernel/exit.c:979 [inline]
>>>>  SyS_exit_group+0x1d/0x20 kernel/exit.c:977
>>>>  entry_SYSCALL_64_fastpath+0x1f/0x96
>>>> RIP: 0033:0x441c78
>>>> RSP: 002b:00007ffe68e20f68 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
>>>> RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 0000000000441c78
>>>> RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000
>>>> RBP: 00000000006cd018 R08: 00000000000000e7 R09: ffffffffffffffd0
>>>> R10: 0000000000000012 R11: 0000000000000246 R12: 0000000000404080
>>>> R13: 0000000000404110 R14: 0000000000000000 R15: 0000000000000000
>>>> Code: 0f 1f 80 00 00 00 00 55 48 89 e5 0f 20 d8 5d c3 0f 1f 80 00 00 00 00
>>>> 55 48 89 e5 0f 22 df 5d c3 0f 1f 80 00 00 00 00 55 48 89 e5 <0f> 22 e7 5d c3
>>>> 0f 1f 80 00 00 00 00 55 48 89 e5 44 0f 20 c0 5d
>>>> RIP: native_write_cr4+0x4/0x10 arch/x86/include/asm/special_insns.h:76 RSP:
>>>> ffff8801ca6f75a0
>>>> ---[ end trace ca14f0c15b26c251 ]---
>>>>
>>>>
>>>> ---
>>>> This bug is generated by a dumb bot. It may contain errors.
>>>> See https://goo.gl/tpsmEJ for details.
>>>> Direct all questions to syzkaller@xxxxxxxxxxxxxxxxx
>>>> Please credit me with: Reported-by: syzbot <syzkaller@xxxxxxxxxxxxxxxx>
>>>>
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