kernel BUG at arch/x86/kvm/x86.c:LINE!

[syzbot]

Hello,

syzkaller hit the following crash on
bb70832dd42b298d4303fd054bf18a78650ff04a
git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/master
compiler: gcc (GCC) 7.1.1 20170620
.config is attached
Raw console output is attached.

syzkaller reproducer is attached. See https://goo.gl/kgGztJ
for information about syzkaller reproducers


kernel BUG at arch/x86/kvm/x86.c:7150!
invalid opcode: 0000 [#1] SMP KASAN
Dumping ftrace buffer:
(ftrace buffer empty)
Modules linked in:
CPU: 3 PID: 3029 Comm: syz-executor0 Not tainted 4.13.0-rc5-next-20170817+
#5
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
task: ffff88006c488700 task.stack: ffff880067800000
RIP: 0010:complete_emulated_mmio+0x5be/0x6f0 arch/x86/kvm/x86.c:7150
RSP: 0018:ffff880067807620 EFLAGS: 00010297
RAX: ffff88006c488700 RBX: ffff880039428040 RCX: ffff88003942845c
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff880039428260
RBP: ffff880067807660 R08: 0000000000000000 R09: ffffed000cf00f2c
R10: ffff880067807a58 R11: ffff8800678079d0 R12: ffffffff810d0840
R13: ffff880039c71000 R14: ffff88006da89f00 R15: ffff880039428040
FS: 00007f8311e83700(0000) GS:ffff88006df00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f04f6102000 CR3: 000000003d5de000 CR4: 00000000000026e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
kvm_arch_vcpu_ioctl_run+0x2e2b/0x58b0 arch/x86/kvm/x86.c:7220
kvm_vcpu_ioctl+0x64c/0x1010 arch/x86/kvm/../../../virt/kvm/kvm_main.c:2591
vfs_ioctl fs/ioctl.c:45 [inline]
do_vfs_ioctl+0x1b1/0x1520 fs/ioctl.c:685
SYSC_ioctl fs/ioctl.c:700 [inline]
SyS_ioctl+0x8f/0xc0 fs/ioctl.c:691
entry_SYSCALL_64_fastpath+0x1f/0xbe
RIP: 0033:0x446749
RSP: 002b:00007f8311e82c08 EFLAGS: 00000282 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 0000000000446749
RDX: 0000000000000000 RSI: 000000000000ae80 RDI: 0000000000000005
RBP: 0000000000a5f870 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000282 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f8311e839c0 R15: 00007f8311e83700
Code: 01 00 00 00 48 89 df e8 51 9e 47 00 44 89 e6 4c 89 f7 45 31 e4 e8 93
25 4d 00 45 85 ed 41 0f 94 c4 e9 c5 fc ff ff e8 f2 2e 60 00 <0f> 0b e8 1b
99 94 00 e9 a0 fa ff ff 89 45 c8 e8 0e 99 94 00 8b
RIP: complete_emulated_mmio+0x5be/0x6f0 arch/x86/kvm/x86.c:7150 RSP:
ffff880067807620
---[ end trace f2b488a12d890bf5 ]---
Kernel panic - not syncing: Fatal exception
Dumping ftrace buffer:
(ftrace buffer empty)
Kernel Offset: disabled
Rebooting in 86400 seconds..


---
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See https://goo.gl/tpsmEJ for details.
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[Dmitry Vyukov]

On Fri, Oct 27, 2017 at 10:34 AM, syzbot
<bot+4facc37258a582d017...@syzkaller.appspotmail.com>
wrote:

> Hello,
>
> syzkaller hit the following crash on
> bb70832dd42b298d4303fd054bf18a78650ff04a
> git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/master
> compiler: gcc (GCC) 7.1.1 20170620
> .config is attached
> Raw console output is attached.
>
> syzkaller reproducer is attached. See https://goo.gl/kgGztJ
> for information about syzkaller reproducers

Last happened on upstream 4ed590271a65b0fbe3eb1cf828ad5af16603c8ce (Oct 26).

device syz5 entered promiscuous mode
------------[ cut here ]------------
kernel BUG at arch/x86/kvm/x86.c:7182!

invalid opcode: 0000 [#1] SMP KASAN
Dumping ftrace buffer:
(ftrace buffer empty)
Modules linked in:

CPU: 0 PID: 5788 Comm: syz-executor3 Not tainted 4.14.0-rc6+ #148
Hardware name: Google Google Compute Engine/Google Compute Engine,
BIOS Google 01/01/2011
task: ffff8801cdc002c0 task.stack: ffff8801974d8000
RIP: 0010:complete_emulated_mmio+0x5c2/0x6f0 arch/x86/kvm/x86.c:7182
RSP: 0000:ffff8801974df620 EFLAGS: 00010216
RAX: 0000000000010000 RBX: ffff8801d2948ac0 RCX: ffffc9000204f000
RDX: 000000000000009b RSI: ffffffff810d5db2 RDI: ffff8801d2948ce0
RBP: ffff8801974df660 R08: 0000000000000000 R09: ffffed0032e9bf2c
R10: 0000000000000000 R11: 0000000000000000 R12: ffffffff810d57f0
R13: ffff8801d87fc000 R14: ffff8801d073d780 R15: ffff8801d2948ac0
FS: 00007fb474244700(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000

CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033

CR2: 000000c438c9b000 CR3: 00000001dad6b000 CR4: 00000000001426f0
DR0: 0000000020000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
kvm_arch_vcpu_ioctl_run+0x2e07/0x5c70 arch/x86/kvm/x86.c:7261
kvm_vcpu_ioctl+0x64c/0x1010 arch/x86/kvm/../../../virt/kvm/kvm_main.c:2551

vfs_ioctl fs/ioctl.c:45 [inline]
do_vfs_ioctl+0x1b1/0x1520 fs/ioctl.c:685
SYSC_ioctl fs/ioctl.c:700 [inline]
SyS_ioctl+0x8f/0xc0 fs/ioctl.c:691
entry_SYSCALL_64_fastpath+0x1f/0xbe

RIP: 0033:0x452869
RSP: 002b:00007fb474243be8 EFLAGS: 00000212 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000758190 RCX: 0000000000452869
RDX: 0000000000000000 RSI: 000000000000ae80 RDI: 0000000000000015
RBP: 0000000000000082 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000212 R12: 0000000000000000
R13: 0000000000a6f7ff R14: 00007fb4742449c0 R15: 0000000000000002
Code: 01 00 00 00 48 89 df e8 ad 9c 47 00 44 89 e6 4c 89 f7 45 31 e4
e8 2f 42 4d 00 45 85 ed 41 0f 94 c4 e9 5f fc ff ff e8 8e 63 60 00 <0f>
0b e8 07 29 95 00 e9 9c fa ff ff 89 45 c8 e8 fa 28 95 00 8b
RIP: complete_emulated_mmio+0x5c2/0x6f0 arch/x86/kvm/x86.c:7182 RSP:
ffff8801974df620
---[ end trace f3b46bcb7f943cb5 ]---

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[Wanpeng Li]

Hi Dmitry,

2017-10-27 16:34 GMT+08:00 Dmitry Vyukov <dvy...@google.com>:
> On Fri, Oct 27, 2017 at 10:34 AM, syzbot
> <bot+4facc37258a582d017...@syzkaller.appspotmail.com>
> wrote:
>> Hello,
>>
>> syzkaller hit the following crash on
>> bb70832dd42b298d4303fd054bf18a78650ff04a
>> git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/master
>> compiler: gcc (GCC) 7.1.1 20170620
>> .config is attached
>> Raw console output is attached.
>>
>> syzkaller reproducer is attached. See https://goo.gl/kgGztJ
>> for information about syzkaller reproducers
>

Coud you post a c program?

Regards,
Wanpeng Li

[Dmitry Vyukov]

On Fri, Oct 27, 2017 at 10:48 AM, Wanpeng Li <kern...@gmail.com> wrote:
> Hi Dmitry,
> 2017-10-27 16:34 GMT+08:00 Dmitry Vyukov <dvy...@google.com>:
>> On Fri, Oct 27, 2017 at 10:34 AM, syzbot
>> <bot+4facc37258a582d017...@syzkaller.appspotmail.com>
>> wrote:
>>> Hello,
>>>
>>> syzkaller hit the following crash on
>>> bb70832dd42b298d4303fd054bf18a78650ff04a
>>> git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/master
>>> compiler: gcc (GCC) 7.1.1 20170620
>>> .config is attached
>>> Raw console output is attached.
>>>
>>> syzkaller reproducer is attached. See https://goo.gl/kgGztJ
>>> for information about syzkaller reproducers
>>
>
> Coud you post a c program?

Please refer to this section of the referenced document:
https://github.com/google/syzkaller/blob/master/docs/syzbot.md#no-reproducer-at-all

[Dmitry Vyukov]

On Fri, Oct 27, 2017 at 11:11 AM, Dmitry Vyukov <dvy...@google.com> wrote:
> On Fri, Oct 27, 2017 at 10:48 AM, Wanpeng Li <kern...@gmail.com> wrote:
>> Hi Dmitry,
>> 2017-10-27 16:34 GMT+08:00 Dmitry Vyukov <dvy...@google.com>:
>>> On Fri, Oct 27, 2017 at 10:34 AM, syzbot
>>> <bot+4facc37258a582d017...@syzkaller.appspotmail.com>
>>> wrote:
>>>> Hello,
>>>>
>>>> syzkaller hit the following crash on
>>>> bb70832dd42b298d4303fd054bf18a78650ff04a
>>>> git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/master
>>>> compiler: gcc (GCC) 7.1.1 20170620
>>>> .config is attached
>>>> Raw console output is attached.
>>>>
>>>> syzkaller reproducer is attached. See https://goo.gl/kgGztJ
>>>> for information about syzkaller reproducers
>>>
>>
>> Coud you post a c program?
>
> Please refer to this section of the referenced document:
> https://github.com/google/syzkaller/blob/master/docs/syzbot.md#no-reproducer-at-all

and this one:
https://github.com/google/syzkaller/blob/master/docs/syzbot.md#syzkaller-reproducers

[Eric Biggers]

Just to follow up on this bug: this crash is no longer occurring and it seems to
have been fixed since v4.15-rc2 by commit 61cb57c9ed631c, so telling syzbot:

#syz fix: KVM: x86: Exit to user-mode on #UD intercept when emulator requires

- Eric