From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail143.messagelabs.com (mail143.messagelabs.com [216.82.254.35]) by kanga.kvack.org (Postfix) with ESMTP id 1EEF16B004F for ; Sun, 31 May 2009 06:23:46 -0400 (EDT) Date: Sun, 31 May 2009 11:24:40 +0100 From: Alan Cox Subject: Re: [patch 0/5] Support for sanitization flag in low-level page allocator Message-ID: <20090531112440.50cbc4fd@lxorguk.ukuu.org.uk> In-Reply-To: <84144f020905302314w12c4c7f8jc8241e36c847f53e@mail.gmail.com> References: <20090528090836.GB6715@elte.hu> <20090530082048.GM29711@oblivion.subreption.com> <20090530173428.GA20013@elte.hu> <20090530180333.GH6535@oblivion.subreption.com> <20090530182113.GA25237@elte.hu> <20090530184534.GJ6535@oblivion.subreption.com> <20090530190828.GA31199@elte.hu> <4A21999E.5050606@redhat.com> <84144f020905301353y2f8c232na4c5f9dfb740eec4@mail.gmail.com> <20090531001052.40ac57d2@lxorguk.ukuu.org.uk> <84144f020905302314w12c4c7f8jc8241e36c847f53e@mail.gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: Pekka Enberg Cc: Rik van Riel , Ingo Molnar , "Larry H." , linux-kernel@vger.kernel.org, Linus Torvalds , linux-mm@kvack.org, Ingo Molnar , pageexec@freemail.hu, Linus Torvalds List-ID: > On Sun, May 31, 2009 at 2:10 AM, Alan Cox wrote: > > #2 Using kzfree() to clear specific bits of memory (and I question the > > kzfree implementation as it seems ksize can return numbers much much > > bigger than the allocated space you need to clear - correct but oversize) > > or using other flags. I'd favour kzfree personally (and fixing it to work > > properly) > > Well, yes, that's what kzfree() needs to do given the current API. I > am not sure why you think it's a problem, though. Adding a size > argument to the function will make it more error prone. Definitely - am I right however that x = kzalloc(size, flags) blah kzfree(x) can memset a good deal more memory (still safely) than "size" to zero ? That has performance relevance if so and it ought to at least be documented. > On Sun, May 31, 2009 at 2:10 AM, Alan Cox wrote: > > #3 People wanting to be able to select for more security *irrespective* > > of performance cost. Which is no different to SELinux for example. > > Yeah, as I said before, I really don't have any objections to this. I > just think nobody is going to enable it so memset() or kzfree() in > relevant places is probably a good idea. Agreed entirely. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org