linux-kernel - Re: Minor PKRU bug?

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Message-ID: <57850D8A.9090801@linux.intel.com>
Date:	Tue, 12 Jul 2016 08:32:26 -0700
From:	Dave Hansen <dave.hansen@...ux.intel.com>
To:	Andy Lutomirski <luto@...capital.net>, X86 ML <x86@...nel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: Minor PKRU bug?

On 07/09/2016 02:27 PM, Andy Lutomirski wrote:
> is_prefetch in arch/x86/mm/fault.c can be called on a user address
> that's not readable due to PKRU.  This could break it.  You might need
> to add a get_user_exec or similar.

Thanks for the heads-up.  I think I'll just need a version that does
something along the lines of stac/clac, but with PKRU.

I think I can do it with an "_exec" variant of probe_kernel_address(),
but it's a bit messy.