linux-kernel - Re: [PATCH V3] mm: Add sysfs interface to dump each node's zonelist information

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Message-Id: <57CF90C8.6050409@linux.vnet.ibm.com>
Date:   Wed, 07 Sep 2016 09:30:08 +0530
From:   Anshuman Khandual <khandual@...ux.vnet.ibm.com>
To:     Kees Cook <keescook@...omium.org>,
        Dave Hansen <dave.hansen@...el.com>,
        Anshuman Khandual <khandual@...ux.vnet.ibm.com>
CC:     Linux-MM <linux-mm@...ck.org>, LKML <linux-kernel@...r.kernel.org>,
        Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH V3] mm: Add sysfs interface to dump each node's zonelist
 information

On 09/07/2016 08:38 AM, Kees Cook wrote:
> On Tue, Sep 6, 2016 at 1:36 PM, Dave Hansen <dave.hansen@...el.com> wrote:
>> On 09/06/2016 01:31 AM, Anshuman Khandual wrote:
>>> [NODE (0)]
>>>         ZONELIST_FALLBACK
>>>         (0) (node 0) (zone DMA c00000000140c000)
>>>         (1) (node 1) (zone DMA c000000100000000)
>>>         (2) (node 2) (zone DMA c000000200000000)
>>>         (3) (node 3) (zone DMA c000000300000000)
>>>         ZONELIST_NOFALLBACK
>>>         (0) (node 0) (zone DMA c00000000140c000)
>>
>> Don't we have some prohibition on dumping out kernel addresses like this
>> so that attackers can't trivially defeat kernel layout randomization?
> 
> Anything printing memory addresses should be using %pK (not %lx as done here).

Learned about the significance of %pK coupled with kptr_restrict
interface. Will change this. Thanks for pointing out.