Subject: Re: BUG: unable to handle kernel paging request in __switch_to
To: Dmitry Vyukov <dvyukov@google.com>,
        Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andy Lutomirski <luto@kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        syzbot 
        <bot+1f445b1009b8eeededa30fe62ccf685f2ec9d155@syzkaller.appspotmail.com>,
        Borislav Petkov <bp@suse.de>, Dmitry Safonov <dsafonov@virtuozzo.com>,
        Peter Anvin <hpa@zytor.com>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Kyle Huey <me@kylehuey.com>, Ingo Molnar <mingo@redhat.com>,
        syzkaller-bugs@googlegroups.com,
        the arch/x86 maintainers <x86@kernel.org>,
        Paolo Bonzini <pbonzini@redhat.com>,
        =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= <rkrcmar@redhat.com>,
        KVM list <kvm@vger.kernel.org>, tianyu.lan@intel.com,
        James Mattson <jmattson@google.com>, Wanpeng Li <kernellwp@gmail.com>
References: <001a1145e8548cbd3d055f73374f@google.com>
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 <CA+55aFw7JJjdmG0R9Vwz8NLOS9npDfyLd8zJ=TP68JufUoph1A@mail.gmail.com>
 <CALCETrWgfgewYk1tkBE6cLqF-mVhRNOJm9_Z45_shsiiNJc1Fw@mail.gmail.com>
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 <CACT4Y+buFtqoO6KF0ZW1HQTMC3rVZ=_0FQq826TmWLZyxkPcwA@mail.gmail.com>
From: David Hildenbrand <david@redhat.com>
Organization: Red Hat GmbH
Message-ID: <1036ed60-035c-70a0-0a5f-00efe8ebf4da@redhat.com>
Date: Fri, 15 Dec 2017 10:51:56 +0100
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> int main()
> {
>   int fd = open("/dev/kvm", 0x80102ul);
>   int vm = ioctl(fd, KVM_CREATE_VM, 0);
>   int  cpu = ioctl(vm, KVM_CREATE_VCPU, 4);

Not even a memory region :) So maybe the first memory access directly
triggers a fault?

>   ioctl(cpu, KVM_RUN, 0);
>   return 0;
> }
> 
> And, yes, this in fact triggers instant reboot of kernel (running in qemu).
> Am I missing something here?
> 
> +kvm maintainers, you can see full thread here:
> https://groups.google.com/forum/#!topic/syzkaller-bugs/_oveOKGm3jw
> 


-- 

Thanks,

David / dhildenb