linux-kernel - Re: [PATCH 0/5] Volatile Ranges (v12) & LSF-MM discussion fodder

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: <533C3CDD.9090400@zytor.com>
Date:	Wed, 02 Apr 2014 09:37:49 -0700
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Johannes Weiner <hannes@...xchg.org>,
	John Stultz <john.stultz@...aro.org>
CC:	LKML <linux-kernel@...r.kernel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Android Kernel Team <kernel-team@...roid.com>,
	Robert Love <rlove@...gle.com>, Mel Gorman <mel@....ul.ie>,
	Hugh Dickins <hughd@...gle.com>, Dave Hansen <dave@...1.net>,
	Rik van Riel <riel@...hat.com>,
	Dmitry Adamushko <dmitry.adamushko@...il.com>,
	Neil Brown <neilb@...e.de>,
	Andrea Arcangeli <aarcange@...hat.com>,
	Mike Hommey <mh@...ndium.org>, Taras Glek <tglek@...illa.com>,
	Jan Kara <jack@...e.cz>,
	KOSAKI Motohiro <kosaki.motohiro@...il.com>,
	Michel Lespinasse <walken@...gle.com>,
	Minchan Kim <minchan@...nel.org>,
	"linux-mm@...ck.org" <linux-mm@...ck.org>
Subject: Re: [PATCH 0/5] Volatile Ranges (v12) & LSF-MM discussion fodder

On 04/02/2014 09:32 AM, H. Peter Anvin wrote:
> On 04/02/2014 09:30 AM, Johannes Weiner wrote:
>>
>> So between zero-fill and SIGBUS, I'd prefer the one which results in
>> the simpler user interface / fewer system calls.
>>
> 
> The use cases are different; I believe this should be a user space option.
> 

Case in point, for example: imagine a JIT.  You *really* don't want to
zero-fill memory behind the back of your JIT, as all zero memory may not
be a trapping instruction (it isn't on x86, for example, and if you are
unlucky you may be modifying *part* of an instruction.)

Thus, SIGBUS is the only safe option.

	-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/