linux-kernel - Re: [PATCH] x86: make sure IDT is page aligned

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Date:	Fri, 12 Jul 2013 15:43:10 -0700
From:	Kees Cook <keescook@...omium.org>
To:	"H. Peter Anvin" <hpa@...or.com>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"x86@...nel.org" <x86@...nel.org>, Borislav Petkov <bp@...e.de>,
	Fenghua Yu <fenghua.yu@...el.com>,
	Yinghai Lu <yinghai@...nel.org>,
	Seiji Aguchi <seiji.aguchi@....com>,
	PaX Team <pageexec@...email.hu>
Subject: Re: [PATCH] x86: make sure IDT is page aligned

That was the busted patch. See the v2 I sent. Only 64-bit needs
alignment. And after looking more at it, the idt in head_64.S could be
entirely dropped in favor of using the one in arch/x86/kernel/traps.c
(after moving it out of the #ifdef.

-Kees

On Fri, Jul 12, 2013 at 3:28 PM, H. Peter Anvin <hpa@...or.com> wrote:
> On 07/12/2013 11:30 AM, Kees Cook wrote:
>>
>> -     .word 0                         # 32-bit align idt_desc.address
>> +     .word PAGE_SIZE                 # page align idt_desc.address
>>
>
> ... and this is totally confused.  This didn't change alignment one
> iota, it only put the value 4096 into the padding.
>
>         -hpa
>



-- 
Kees Cook
Chrome OS Security
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