linux-kernel - Re: [PATCH v2 0/3] Makefile: Introduce CONFIG_CC_STACKPROTECTOR

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Date:   Wed, 8 Nov 2017 11:43:14 -0800
From:   Laura Abbott <labbott@...hat.com>
To:     Kees Cook <keescook@...omium.org>,
        Andrew Morton <akpm@...ux-foundation.org>
Cc:     Masahiro Yamada <yamada.masahiro@...ionext.com>,
        Arnd Bergmann <arnd@...db.de>,
        Josh Triplett <josh@...htriplett.org>,
        Nicholas Piggin <npiggin@...il.com>,
        linux-kbuild@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 0/3] Makefile: Introduce CONFIG_CC_STACKPROTECTOR_AUTO

On 11/07/2017 09:38 AM, Kees Cook wrote:
> As described in the final patch:
> 
> Nearly all modern compilers support a stack-protector option, and nearly
> all modern distributions enable the kernel stack-protector, so enabling
> this by default in kernel builds would make sense. However, Kconfig does
> not have knowledge of available compiler features, so it isn't safe to
> force on, as this would unconditionally break builds for the compilers
> or architectures that don't have support. Instead, this introduces a new
> option, CONFIG_CC_STACKPROTECTOR_AUTO, which attempts to discover the best
> possible stack-protector available, and will allow builds to proceed even
> if the compiler doesn't support any stack-protector.
> 
> This option is made the default so that kernels built with modern
> compilers will be protected-by-default against stack buffer overflows,
> avoiding things like the recent BlueBorne attack. Selection of a specific
> stack-protector option remains available, including disabling it.
> 
> 
> This has lived over the last several days without any unfixed 0day failures.
> 
> v2:
> - under ..._AUTO, warn and continue on _all_ stack protector failure cases
> - fix 32-bit boot regression due to lazy gz.
> - set CONFIG_CC_STACKPROTECTOR_NONE for tiny.config.
> 
> Thanks,
> 
> -Kees
> 

This passed a test build on all Fedora arches, including s390 and ppc.
On x86 it picks up the strong option correctly.

You're welcome to add

Tested-by: Laura Abbott <labbott@...hat.com>

Thanks,
Laura