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Date: Thu, 16 Jun 2016 08:05:38 +0200
From: Heiko Carstens <>
To: Andy Lutomirski <>
Cc: "" <>,, Borislav Petkov <>,
        Nadav Amit <>, Kees Cook <>,
        Brian Gerst <>,
        "" <>,
        Linus Torvalds <>,
        Josh Poimboeuf <>
Subject: Re: [PATCH 00/13] Virtually mapped stacks with guard pages (x86,

On Wed, Jun 15, 2016 at 05:28:22PM -0700, Andy Lutomirski wrote:
> Since the dawn of time, a kernel stack overflow has been a real PITA
> to debug, has caused nondeterministic crashes some time after the
> actual overflow, and has generally been easy to exploit for root.
> With this series, arches can enable HAVE_ARCH_VMAP_STACK.  Arches
> that enable it (just x86 for now) get virtually mapped stacks with
> guard pages.  This causes reliable faults when the stack overflows.
> If the arch implements it well, we get a nice OOPS on stack overflow
> (as opposed to panicing directly or otherwise exploding badly).  On
> x86, the OOPS is nice, has a usable call trace, and the overflowing
> task is killed cleanly.

Do you have numbers which reflect the performance impact of this change?

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