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=-8.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED, USER_AGENT_MUTT 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 B51BAC43381 for ; Mon, 18 Feb 2019 08:30:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8E9DB2184E for ; Mon, 18 Feb 2019 08:30:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729236AbfBRIaV (ORCPT ); Mon, 18 Feb 2019 03:30:21 -0500 Received: from mx1.redhat.com ([209.132.183.28]:38134 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729197AbfBRIaR (ORCPT ); Mon, 18 Feb 2019 03:30:17 -0500 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 6F24FC02C68F; Mon, 18 Feb 2019 08:30:16 +0000 (UTC) Received: from localhost (ovpn-12-45.pek2.redhat.com [10.72.12.45]) by smtp.corp.redhat.com (Postfix) with ESMTPS id A09DE26E5A; Mon, 18 Feb 2019 08:30:15 +0000 (UTC) Date: Mon, 18 Feb 2019 16:30:13 +0800 From: Baoquan He To: Kees Cook Cc: LKML , Thomas Gleixner , Ingo Molnar , Borislav Petkov , "H. Peter Anvin" , Dave Hansen , Andy Lutomirski , Peter Zijlstra , X86 ML , Mike Travis , Thomas Garnier , Andrew Morton , Masahiro Yamada , "Kirill A. Shutemov" Subject: Re: [PATCH v3 4/6] x86/mm/KASLR: Fix the wrong calculation of memory region initial size Message-ID: <20190218083013.GI14858@MiWiFi-R3L-srv> References: <20190216140008.28671-1-bhe@redhat.com> <20190216140008.28671-5-bhe@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.31]); Mon, 18 Feb 2019 08:30:16 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 02/17/19 at 08:53am, Kees Cook wrote: > On Sat, Feb 16, 2019 at 6:03 AM Baoquan He wrote: > > > > In memory region KASLR, __PHYSICAL_MASK_SHIFT is taken to calculate > > the initial size of the direct mapping region. This is correct in > > the old code where __PHYSICAL_MASK_SHIFT was equal to MAX_PHYSMEM_BITS, > > 46 bits, and only 4-level mode was supported. > > > > Later, in commit b83ce5ee91471d ("x86/mm/64: Make __PHYSICAL_MASK_SHIFT > > always 52"), __PHYSICAL_MASK_SHIFT was changed to be always 52 bits, no > > matter it's 5-level or 4-level. This is wrong for 4-level paging. Then > > when we adapt physical memory region size based on available memory, it > > will overflow if the amount of system RAM and the padding is bigger > > than 64 TB. > > > > In fact, here MAX_PHYSMEM_BITS should be used instead. Fix it by > > replacing __PHYSICAL_MASK_SHIFT with MAX_PHYSMEM_BITS. > > > > Fixes: b83ce5ee9147 ("x86/mm/64: Make __PHYSICAL_MASK_SHIFT always 52") > > Acked-by: Kirill A. Shutemov > > Reviewed-by: Thomas Garnier > > Signed-off-by: Baoquan He > > Nice catch! I wish I had a system with >64TB RAM. ;) > > Acked-by: Kees Cook Thanks for reviewing and ack-ing. I don't have system with 64 TB RAM either. This fix is from code reading. In patch 0006, the UV system issue is a serious regression when I introduced KASLR into RHEL, now even though a RHEL-only fix has been merged in our distros, the tracker bug which tracks upstream fix will go to me during planning stage of each RHEL version. After Kirill pushed 5-level code, SGI UV dev said the old bug can't be reproduced any more in upstream kernel, I read code and found that the code bug fixed in this patch will hide the SGI UV issue :-). > > > --- > > arch/x86/mm/kaslr.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/arch/x86/mm/kaslr.c b/arch/x86/mm/kaslr.c > > index bf680929fe26..97768df923e3 100644 > > --- a/arch/x86/mm/kaslr.c > > +++ b/arch/x86/mm/kaslr.c > > @@ -137,7 +137,7 @@ void __init kernel_randomize_memory(void) > > if (!kaslr_memory_enabled()) > > return; > > > > - kaslr_regions[0].size_tb = 1 << (__PHYSICAL_MASK_SHIFT - TB_SHIFT); > > + kaslr_regions[0].size_tb = 1 << (MAX_PHYSMEM_BITS - TB_SHIFT); > > kaslr_regions[1].size_tb = VMALLOC_SIZE_TB; > > > > /* > > -- > > 2.17.2 > > > > > -- > Kees Cook