linux-kernel - Re: [PATCH 1/4] [tip:x86/mm] Correcting improper large page preservation

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <g2g817ecb6f1004060751s1fd3d42bqc19b5c36b33c3c13@mail.gmail.com>
Date:	Tue, 6 Apr 2010 10:51:44 -0400
From:	Siarhei Liakh <sliakh.lkml@...il.com>
To:	Suresh Siddha <suresh.b.siddha@...el.com>
Cc:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-security-module@...r.kernel.org" 
	<linux-security-module@...r.kernel.org>,
	"linux-next@...r.kernel.org" <linux-next@...r.kernel.org>,
	Arjan van de Ven <arjan@...radead.org>,
	James Morris <jmorris@...ei.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Andi Kleen <ak@....de>, Thomas Gleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>, Ingo Molnar <mingo@...e.hu>,
	Rusty Russell <rusty@...tcorp.com.au>,
	Stephen Rothwell <sfr@...b.auug.org.au>,
	Dave Jones <davej@...hat.com>
Subject: Re: [PATCH 1/4] [tip:x86/mm] Correcting improper large page 
	preservation

On Sat, Apr 3, 2010 at 2:43 AM, Suresh Siddha <suresh.b.siddha@...el.com> wrote:
> On Wed, 2010-03-31 at 18:59 -0700, Siarhei Liakh wrote:
>> +     /*
>> +      * .data and .bss should always be writable.
>> +      */
>> +     if ((within(pfn, __pa((unsigned long)_sdata) >> PAGE_SHIFT,
>> +                __pa((unsigned long)_edata) >> PAGE_SHIFT)) ||
>> +         (within(pfn, __pa((unsigned long)__bss_start) >> PAGE_SHIFT,
>> +                __pa((unsigned long)__bss_stop) >> PAGE_SHIFT))) {
>> +             pgprot_val(required) |= _PAGE_RW;
>> +     }
>
> I have reviewed this patch and the only comment I have is:
>
> On 64bit kernels, kernel text/data mapping and kernel identity mappings
> are different virtual addresses mapping to same pfn ranges. For the
> data/bss pages, does it help (in identifying certain data corruptions
> more easily) in making the kernel identity mapping to be set to
> read-only and enforce the need of RW only for the kernel data mappings.
>
> Or is there some obscure code that uses something like
> __va(__pa(data_symbol)) and writes to it?
>
> If not, we can remove the __pa() constructs above and use the addr for
> comparisons.

Done.
Patch V2 have been posted.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/