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SubjectRe: WARNING in x86_emulate_insn
Hi Dmitry:
I tried to reproduce the issue via syz-execprog with attached
reproducer on latest linux-next but it causes VM-entry failure due to
invalid guest state...

2017-12-07 14:25 GMT+08:00 Dmitry Vyukov <dvyukov@google.com>:
> On Thu, Dec 7, 2017 at 1:44 AM, Wanpeng Li <kernellwp@gmail.com> wrote:
>> 2017-12-06 4:07 GMT+08:00 syzbot
>> <bot+75375385991b4f8c599704a10849863c586ea284@syzkaller.appspotmail.com>:
>>> Hello,
>>>
>>> syzkaller hit the following crash on
>>> fb20eb9d798d2f4c1a75b7fe981d72dfa8d7270d
>>> 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
>>>
>>
>> Is there a c program to reproduce?
>
> No, syzbot does not hide reproducers. See the referenced doc for
> details: https://github.com/google/syzkaller/blob/master/docs/syzbot.md#syzkaller-reproducers
>
>
>> Regards,
>> Wanpeng Li
>>
>>>
>>> kvm: KVM_SET_TSS_ADDR need to be called before entering vcpu
>>> WARNING: CPU: 1 PID: 3526 at arch/x86/kvm/emulate.c:5654
>>> x86_emulate_insn+0xd01/0x3cf0 arch/x86/kvm/emulate.c:5654
>>> Kernel panic - not syncing: panic_on_warn set ...
>>>
>>> CPU: 1 PID: 3526 Comm: syz-executor4 Not tainted 4.15.0-rc1-next-20171201+
>>> #57
>>> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
>>> Google 01/01/2011
>>> Call Trace:
>>> __dump_stack lib/dump_stack.c:17 [inline]
>>> dump_stack+0x194/0x257 lib/dump_stack.c:53
>>> panic+0x1e4/0x41c kernel/panic.c:183
>>> __warn+0x1dc/0x200 kernel/panic.c:547
>>> report_bug+0x211/0x2d0 lib/bug.c:184
>>> fixup_bug.part.11+0x37/0x80 arch/x86/kernel/traps.c:177
>>> fixup_bug arch/x86/kernel/traps.c:246 [inline]
>>> do_error_trap+0x2d7/0x3e0 arch/x86/kernel/traps.c:295
>>> do_invalid_op+0x1b/0x20 arch/x86/kernel/traps.c:314
>>> invalid_op+0x22/0x40 arch/x86/entry/entry_64.S:1066
>>> RIP: 0010:x86_emulate_insn+0xd01/0x3cf0 arch/x86/kvm/emulate.c:5654
>>> RSP: 0018:ffff8801d0fff3e8 EFLAGS: 00010293
>>> RAX: ffff8801d17b60c0 RBX: 1ffff1003a1ffe86 RCX: ffffffff81154351
>>> RDX: 0000000000000000 RSI: ffffffffffffffff RDI: ffff8801d0b5b5c8
>>> RBP: ffff8801d0fff4f8 R08: ffff8801d0b58d80 R09: ffffffff85224da0
>>> R10: 0000000000000001 R11: ffffed003a16b6d4 R12: 00000000000000ff
>>> R13: ffff8801d0b5b5a0 R14: 0000000000000002 R15: ffff8801d0b5b6c3
>>> x86_emulate_instruction+0x411/0x1ad0 arch/x86/kvm/x86.c:5771
>>> emulate_instruction arch/x86/include/asm/kvm_host.h:1164 [inline]
>>> complete_emulated_io arch/x86/kvm/x86.c:7190 [inline]
>>> complete_emulated_pio+0xdd/0x1b0 arch/x86/kvm/x86.c:7201
>>> kvm_arch_vcpu_ioctl_run+0x2db2/0x5c60 arch/x86/kvm/x86.c:7305
>>> kvm_vcpu_ioctl+0x64c/0x1010 arch/x86/kvm/../../../virt/kvm/kvm_main.c:2574
>>> vfs_ioctl fs/ioctl.c:46 [inline]
>>> do_vfs_ioctl+0x1b1/0x1530 fs/ioctl.c:686
>>> SYSC_ioctl fs/ioctl.c:701 [inline]
>>> SyS_ioctl+0x8f/0xc0 fs/ioctl.c:692
>>> entry_SYSCALL_64_fastpath+0x1f/0x96
>>> RIP: 0033:0x4529d9
>>> RSP: 002b:00007f6b6b2d5c58 EFLAGS: 00000212 ORIG_RAX: 0000000000000010
>>> RAX: ffffffffffffffda RBX: 0000000000758020 RCX: 00000000004529d9
>>> RDX: 0000000000000000 RSI: 000000000000ae80 RDI: 0000000000000004
>>> RBP: 000000000000039b R08: 0000000000000000 R09: 0000000000000000
>>> R10: 0000000000000000 R11: 0000000000000212 R12: 00000000006f2728
>>> R13: 00000000ffffffff R14: 00007f6b6b2d66d4 R15: 0000000000000000
>>> Dumping ftrace buffer:
>>> (ftrace buffer empty)
>>> Kernel Offset: disabled
>>> Rebooting in 86400 seconds..
>>>
>>>
>>> ---
>>> This bug is generated by a dumb bot. It may contain errors.
>>> See https://goo.gl/tpsmEJ for details.
>>> Direct all questions to syzkaller@googlegroups.com.
>>> Please credit me with: Reported-by: syzbot <syzkaller@googlegroups.com>
>>>
>>> syzbot will keep track of this bug report.
>>> Once a fix for this bug is committed, please reply to this email with:
>>> #syz fix: exact-commit-title
>>> If you want to test a patch for this bug, please reply with:
>>> #syz test: git://repo/address.git branch
>>> and provide the patch inline or as an attachment.
>>> To mark this as a duplicate of another syzbot report, please reply with:
>>> #syz dup: exact-subject-of-another-report
>>> If it's a one-off invalid bug report, please reply with:
>>> #syz invalid
>>> Note: if the crash happens again, it will cause creation of a new bug
>>> report.
>>> Note: all commands must start from beginning of the line in the email body.
>>
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--
Best regards
Tianyu Lan

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