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Date: Wed, 20 Sep 2017 10:15:56 +0100
From: Will Deacon <will.deacon@arm.com>
To: Kees Cook <keescook@chromium.org>
Cc: Mark Salyzyn <salyzyn@android.com>,
        Catalin Marinas <catalin.marinas@arm.com>,
        LKML <linux-kernel@vger.kernel.org>, kevin.brodsky@arm.com,
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Subject: Re: [PATCH v3 0/3] arm64: Add CONFIG_KUSER_HELPERS
Message-ID: <20170920091555.GA3782@arm.com>
References: <20170911152635.95367-1-salyzyn@android.com>
 <CAGXu5jK-i_Eqfm1mZ-Kz5dqsKuCt_-MDymkb735VXCV9aOnvwQ@mail.gmail.com>
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On Tue, Sep 19, 2017 at 03:02:22PM -0700, Kees Cook wrote:
> On Mon, Sep 11, 2017 at 8:26 AM, Mark Salyzyn <salyzyn@android.com> wrote:
> > Make it possible to disable the kuser helpers by adding a KUSER_HELPERS
> > config option (enabled by default). When disabled, all kuser
> > helpers-related code is removed from the kernel and no mapping is done
> > at the fixed high address (0xffff0000); any attempt to use a kuser
> > helper from a 32-bit process will result in a segfault.
> >
> > Signed-off-by: Mark Salyzyn <salyzyn@android.com>
> >
> > v2:
> > - vectors_page and compat_vdso_spec as array of 2
> > - free sigpage if vectors allocation failed
> > - adjust makefile so one line for each of the assembler source modules
> > - split off assembler changes to a new previous patch in series to reduce churn
> > - modify slightly the feature documentation to reduce its reach
> > - modify slightly the feature documentation to rationalize the yes default.
> > - There are more ifdefs as a result of the rebase.
> >
> > v3:
> > - rebase (minor conflicts)
> 
> This looks great to me. I'd love to see kuser helpers gone. :)
> 
> Catalin, Will, does this need anything else?

I haven't had chance to look at the patches yet (buried in other stuff), but
I aim to get to it in the next couple of weeks.

Will