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Subject: Re: [tip:x86/urgent] x86-64, modify_ldt: Ban 16-bit segments on 64-bit kernels
From: "H. Peter Anvin" <hpa@zytor.com>
Date: Sat, 12 Apr 2014 12:44:42 -0700
To: Borislav Petkov <bp@alien8.de>
CC: Brian Gerst <brgerst@gmail.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Ingo Molnar <mingo@kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>, stable <stable@vger.kernel.org>,
        "H. Peter Anvin" <hpa@linux.intel.com>
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Run a 32-bit VM.  The 32-bit kernel does this right.

I suspect it would also work fine in a Qemu user mode guest (is this supported by KVM?), in a ReactOS VM, or some other number of combinations.

The real question is how many real users are actually affected.

On April 12, 2014 12:35:41 PM PDT, Borislav Petkov <bp@alien8.de> wrote:
>On Sat, Apr 12, 2014 at 10:18:25AM -0700, H. Peter Anvin wrote:
>> So Wine regressed and noone noticed? They doesn't sound like an
>active
>> user base.
>
>Btw, wouldn't this obscure use case simply work in a KVM guest with a
>kernel <= 3.14?
>
>Because if so, we simply cut it at 3.14, everything newer has the leak
>fix and people who still want to play phone games on a x86 machine, can
>do so in a guest with an older kernel. Everybody's happy.

-- 
Sent from my mobile phone.  Please pardon brevity and lack of formatting.