linux-kernel - Re: [PATCH 01/11] x86: Use asm goto to implement better modify_and

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] [day] [month] [year] [list]

Message-ID: <523BD277.2040302@zytor.com>
Date:	Thu, 19 Sep 2013 23:43:35 -0500
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Andi Kleen <ak@...ux.intel.com>
CC:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...nel.org>,
	Mike Galbraith <bitbucket@...ine.de>,
	Thomas Gleixner <tglx@...utronix.de>,
	Arjan van de Ven <arjan@...ux.intel.com>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	"linux-arch@...r.kernel.org" <linux-arch@...r.kernel.org>
Subject: Re: [PATCH 01/11] x86: Use asm goto to implement better modify_and_test()
 functions

On 09/19/2013 03:31 AM, Andi Kleen wrote:
> On Wed, Sep 18, 2013 at 02:02:37PM -0500, H. Peter Anvin wrote:
>> Yes, a bit sad.  We allow bracketing with the get/put_user_try/catch blocks, but that is x86-specific.
>>
>> I don't think a generic option is possible without compiler support, but it might be possible to do better than we do know.
>
> Letting the compiler do it is a bit risky, because it may open it up for
> really large blocks, thus defeating the security advantages.
>
> -Andi
>

The compiler support. if done right, should avoid unannotated memory 
references.  This is a pretty big job in the compiler, though.

	-hpa

--
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/