From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 594BAC433DF for ; Sat, 23 May 2020 02:58:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 283BC206DD for ; Sat, 23 May 2020 02:58:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387540AbgEWC6E (ORCPT ); Fri, 22 May 2020 22:58:04 -0400 Received: from smtprelay0024.hostedemail.com ([216.40.44.24]:55848 "EHLO smtprelay.hostedemail.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S2387481AbgEWC6D (ORCPT ); Fri, 22 May 2020 22:58:03 -0400 Received: from filter.hostedemail.com (clb03-v110.bra.tucows.net [216.40.38.60]) by smtprelay03.hostedemail.com (Postfix) with ESMTP id AC0ED837F24C; Sat, 23 May 2020 02:58:02 +0000 (UTC) X-Session-Marker: 6A6F6540706572636865732E636F6D X-HE-Tag: robin60_3f0f18a26d2c X-Filterd-Recvd-Size: 2777 Received: from XPS-9350.home (unknown [47.151.136.130]) (Authenticated sender: joe@perches.com) by omf05.hostedemail.com (Postfix) with ESMTPA; Sat, 23 May 2020 02:58:00 +0000 (UTC) Message-ID: Subject: Re: [PATCH] x86/mm/init: Stop printing pgt_buf addresses From: Joe Perches To: Arvind Sankar Cc: "Tobin C . Harding" , Tycho Andersen , kernel-hardening@lists.openwall.com, Kees Cook , Dave Hansen , Andy Lutomirski , Peter Zijlstra , x86@kernel.org, linux-kernel@vger.kernel.org Date: Fri, 22 May 2020 19:57:59 -0700 In-Reply-To: <20200523015129.GA717759@rani.riverdale.lan> References: <20200229231120.1147527-1-nivedita@alum.mit.edu> <20200523015129.GA717759@rani.riverdale.lan> Content-Type: text/plain; charset="ISO-8859-1" User-Agent: Evolution 3.36.2-0ubuntu1 MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 2020-05-22 at 21:51 -0400, Arvind Sankar wrote: > On Sat, Feb 29, 2020 at 06:11:20PM -0500, Arvind Sankar wrote: > > This currently leaks kernel physical addresses into userspace. > > > > Signed-off-by: Arvind Sankar > > --- > > arch/x86/mm/init.c | 2 -- > > 1 file changed, 2 deletions(-) > > > > diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c > > index e7bb483557c9..dc4711f09cdc 100644 > > --- a/arch/x86/mm/init.c > > +++ b/arch/x86/mm/init.c > > @@ -121,8 +121,6 @@ __ref void *alloc_low_pages(unsigned int num) > > } else { > > pfn = pgt_buf_end; > > pgt_buf_end += num; > > - printk(KERN_DEBUG "BRK [%#010lx, %#010lx] PGTABLE\n", > > - pfn << PAGE_SHIFT, (pgt_buf_end << PAGE_SHIFT) - 1); > > } > > > > for (i = 0; i < num; i++) { > > -- > > 2.24.1 > > > > Ping. > > https://lore.kernel.org/lkml/20200229231120.1147527-1-nivedita@alum.mit.edu/ If this output is at all valuable, perhaps emit them as hashed pointers? Maybe: --- arch/x86/mm/init.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c index 1bba16c5742b..44f0d6592c7e 100644 --- a/arch/x86/mm/init.c +++ b/arch/x86/mm/init.c @@ -121,8 +121,9 @@ __ref void *alloc_low_pages(unsigned int num) } else { pfn = pgt_buf_end; pgt_buf_end += num; - printk(KERN_DEBUG "BRK [%#010lx, %#010lx] PGTABLE\n", - pfn << PAGE_SHIFT, (pgt_buf_end << PAGE_SHIFT) - 1); + printk(KERN_DEBUG "BRK [0x%8p, 0x%8p] PGTABLE\n", + (void *)(pfn << PAGE_SHIFT), + (void *)((pgt_buf_end << PAGE_SHIFT) - 1)); } for (i = 0; i < num; i++) {