linux-kernel - Re: [PATCH v2 1/2] stack: Introduce CONFIG_RANDOMIZE_KSTACK

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Message-Id: <164486603894.3748820.17377347049312013591.b4-ty@chromium.org>
Date:   Mon, 14 Feb 2022 11:14:03 -0800
From:   Kees Cook <keescook@...omium.org>
To:     Marco Elver <elver@...gle.com>,
        Thomas Gleixner <tglx@...utronix.de>
Cc:     Kees Cook <keescook@...omium.org>,
        Alexander Potapenko <glider@...gle.com>,
        Nathan Chancellor <nathan@...nel.org>,
        kasan-dev@...glegroups.com, Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...nel.org>, linux-kernel@...r.kernel.org,
        Elena Reshetova <elena.reshetova@...el.com>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        llvm@...ts.linux.dev
Subject: Re: [PATCH v2 1/2] stack: Introduce CONFIG_RANDOMIZE_KSTACK_OFFSET

On Mon, 31 Jan 2022 10:05:20 +0100, Marco Elver wrote:
> The randomize_kstack_offset feature is unconditionally compiled in when
> the architecture supports it.
> 
> To add constraints on compiler versions, we require a dedicated Kconfig
> variable. Therefore, introduce RANDOMIZE_KSTACK_OFFSET.
> 
> Furthermore, this option is now also configurable by EXPERT kernels:
> while the feature is supposed to have zero performance overhead when
> disabled, due to its use of static branches, there are few cases where
> giving a distribution the option to disable the feature entirely makes
> sense. For example, in very resource constrained environments, which
> would never enable the feature to begin with, in which case the
> additional kernel code size increase would be redundant.
> 
> [...]

Applied to for-next/hardening, thanks!

[1/2] stack: Introduce CONFIG_RANDOMIZE_KSTACK_OFFSET
      https://git.kernel.org/kees/c/8cb37a5974a4
[2/2] stack: Constrain and fix stack offset randomization with Clang builds
      https://git.kernel.org/kees/c/efa90c11f62e

-- 
Kees Cook