linux-kernel - Re: [PATCH] ARM: fix atags_to_fdt with stack-protector-strong

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Message-ID: <CAGXu5j+xgvQu5-=F33TfQye9O96O+DhzxBq0x3M_sZGhQJxPOA@mail.gmail.com>
Date:	Fri, 18 Dec 2015 13:26:24 -0800
From:	Kees Cook <keescook@...omium.org>
To:	Arnd Bergmann <arnd@...db.de>
Cc:	Russell King <linux@....linux.org.uk>,
	LKML <linux-kernel@...r.kernel.org>,
	Jeffy <jeffy.chen@...k-chips.com>,
	Simon Horman <horms+renesas@...ge.net.au>,
	Geert Uytterhoeven <geert+renesas@...der.be>,
	Laurent Pinchart <laurent.pinchart@...asonboard.com>,
	Magnus Damm <damm+renesas@...nsource.se>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH] ARM: fix atags_to_fdt with stack-protector-strong

On Fri, Dec 18, 2015 at 1:09 PM, Arnd Bergmann <arnd@...db.de> wrote:
> On Friday 18 December 2015 13:04:59 Kees Cook wrote:
>> +ifeq ($(CONFIG_ARM_ATAG_DTB_COMPAT),y)
>> +CFLAGS_atags_to_fdt.o := -fno-stack-protector
>> +CFLAGS_fdt.o := -fno-stack-protector
>> +CFLAGS_fdt_ro.o := -fno-stack-protector
>> +CFLAGS_fdt_rw.o := -fno-stack-protector
>> +CFLAGS_fdt_wip.o := -fno-stack-protector
>> +endif
>
> I'm pretty sure you don't need the ifeq there, you can simply define those
> flags unconditionally.
>
> You can't just add -fno-stack-protector unconditionally, because that
> breaks building the kernel with toolchains that are older than stack-protector,
> so this should be
>
> CFLAGS_obj.o += $(call cc-option, -fno-stack-protector)
>
> Other than that, the patch looks ok.

Ah, yes, all excellent points. I'll resend. Thanks!

-Kees

-- 
Kees Cook
Chrome OS & Brillo Security
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