From mboxrd@z Thu Jan 1 00:00:00 1970 From: James Bottomley Subject: Re: [PATCH] kernel buffer overflow kmalloc_slab() fix Date: Fri, 20 May 2011 16:02:51 +0400 Message-ID: <1305892971.2571.16.camel@mulgrave.site> References: <1305834712-27805-2-git-send-email-james_p_freyensee@linux.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Return-path: Received: from bedivere.hansenpartnership.com ([66.63.167.143]:44582 "EHLO bedivere.hansenpartnership.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S935666Ab1ETMGz (ORCPT ); Fri, 20 May 2011 08:06:55 -0400 In-Reply-To: Sender: linux-arch-owner@vger.kernel.org List-ID: To: Christoph Lameter Cc: james_p_freyensee@linux.intel.com, linux-mm@kvack.org, gregkh@suse.de, hari.k.kanigeri@intel.com, linux-arch@vger.kernel.org On Thu, 2011-05-19 at 15:51 -0500, Christoph Lameter wrote: > On Thu, 19 May 2011, james_p_freyensee@linux.intel.com wrote: > > > From: J Freyensee > > > > Currently, kmalloc_index() can return -1, which can be > > passed right to the kmalloc_caches[] array, cause a > > No kmalloc_index() cannot return -1 for the use case that you are > considering here. The value passed as a size to > kmalloc_slab is bounded by 2 * PAGE_SIZE and kmalloc_slab will only return > -1 for sizes > 4M. So we will have to get machines with page sizes > 2M > before this can be triggered. Please don't make x86 centric assumptions like this. I was vaguely thinking about hugepages in parisc. Like most risc machines, we have (and have had for over a decade) a vast number of variable size pages (actually from 4k to 64MB in power of 4 steps) and I think sparc is similar, so I was wondering what to choose. You'd have been deeply annoyed if I'd chosen 4MB and had slub fall over (again). linux-arch cc'd just so everyone else is aware of these limitations when they implement hugepages. James