linux-kernel - Re: [RESEND][PATCH] kbuild: Abort build on bad stack protector flag

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Date:	Tue, 26 Jul 2016 23:06:13 +0200
From:	Michal Marek <mmarek@...e.com>
To:	Kees Cook <keescook@...omium.org>
Cc:	Ingo Molnar <mingo@...nel.org>,
	Andrew Morton <akpm@...ux-foundation.org>, x86@...nel.org,
	linux-kbuild@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [RESEND][PATCH] kbuild: Abort build on bad stack protector flag

On Tue, Jul 12, 2016 at 03:30:43PM -0700, Kees Cook wrote:
> Before, the stack protector flag was sanity checked before .config had
> been reprocessed. This meant the build couldn't be aborted early, and
> only a warning could be emitted followed later by the compiler blowing
> up with an unknown flag. This has caused a lot of confusion over time,
> so this splits the flag selection from sanity checking and performs the
> sanity checking after the make has been restarted from a reprocessed
> .config, so builds can be aborted as early as possible now.
> 
> Additionally moves the x86-specific sanity check to the same location,
> since it suffered from the same warn-then-wait-for-compiler-failure
> problem.
> 
> Signed-off-by: Kees Cook <keescook@...omium.org>

Hi Kees,

sorry for the late review.


> +# Find arch-specific stack protector compiler sanity-checking script.
> +ifdef CONFIG_CC_STACKPROTECTOR
> +  stackp-path := $(srctree)/scripts/gcc-$(ARCH)_$(BITS)-has-stack-protector.sh

You need to use SRCARCH here if you want "x86" on x86.


> +  ifneq ($(wildcard $(stackp-path)),)
> +    stackp-check := $(stackp-path)
> +  endif

stackp-check := $(wildcard $(stackp-path))

is more straightforward. But the long version is correct as well.

Michal