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=-7.0 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 0DF7BC4360C for ; Mon, 30 Sep 2019 05:54:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DEB852168B for ; Mon, 30 Sep 2019 05:54:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729627AbfI3FyF (ORCPT ); Mon, 30 Sep 2019 01:54:05 -0400 Received: from ushosting.nmnhosting.com ([66.55.73.32]:59674 "EHLO ushosting.nmnhosting.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728162AbfI3FyE (ORCPT ); Mon, 30 Sep 2019 01:54:04 -0400 Received: from mail2.nmnhosting.com (unknown [202.78.40.170]) by ushosting.nmnhosting.com (Postfix) with ESMTPS id 8E0E72DC006C; Mon, 30 Sep 2019 01:54:03 -0400 (EDT) Received: from adsilva.ozlabs.ibm.com (static-82-10.transact.net.au [122.99.82.10] (may be forged)) (authenticated bits=0) by mail2.nmnhosting.com (8.15.2/8.15.2) with ESMTPSA id x8U5rh60025864 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NO); Mon, 30 Sep 2019 15:53:59 +1000 (AEST) (envelope-from alastair@d-silva.org) Message-ID: Subject: Re: [PATCH v5 1/1] memory_hotplug: Add a bounds check to __add_pages From: "Alastair D'Silva" To: "Alastair D'Silva" Cc: Andrew Morton , Oscar Salvador , Michal Hocko , David Hildenbrand , Pavel Tatashin , Dan Williams , linux-mm@kvack.org, linux-kernel@vger.kernel.org Date: Mon, 30 Sep 2019 15:53:42 +1000 In-Reply-To: <20190930022152.14114-2-alastair@au1.ibm.com> References: <20190930022152.14114-1-alastair@au1.ibm.com> <20190930022152.14114-2-alastair@au1.ibm.com> Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.32.4 (3.32.4-1.fc30) MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Greylist: Sender succeeded SMTP AUTH, not delayed by milter-greylist-4.6.2 (mail2.nmnhosting.com [10.0.1.20]); Mon, 30 Sep 2019 15:54:00 +1000 (AEST) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 2019-09-30 at 12:21 +1000, Alastair D'Silva wrote: > From: Alastair D'Silva > > On PowerPC, the address ranges allocated to OpenCAPI LPC memory > are allocated from firmware. These address ranges may be higher > than what older kernels permit, as we increased the maximum > permissable address in commit 4ffe713b7587 > ("powerpc/mm: Increase the max addressable memory to 2PB"). It is > possible that the addressable range may change again in the > future. > > In this scenario, we end up with a bogus section returned from > __section_nr (see the discussion on the thread "mm: Trigger bug on > if a section is not found in __section_nr"). > > Adding a check here means that we fail early and have an > opportunity to handle the error gracefully, rather than rumbling > on and potentially accessing an incorrect section. > > Further discussion is also on the thread ("powerpc: Perform a bounds > check in arch_add_memory") > http://lkml.kernel.org/r/20190827052047.31547-1-alastair@au1.ibm.com > > Signed-off-by: Alastair D'Silva > --- > mm/memory_hotplug.c | 20 ++++++++++++++++++++ > 1 file changed, 20 insertions(+) > > diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c > index c73f09913165..1909607da640 100644 > --- a/mm/memory_hotplug.c > +++ b/mm/memory_hotplug.c > @@ -278,6 +278,22 @@ static int check_pfn_span(unsigned long pfn, > unsigned long nr_pages, > return 0; > } > > +static int check_hotplug_memory_addressable(unsigned long pfn, > + unsigned long nr_pages) > +{ > + const u64 max_addr = PFN_PHYS(pfn + nr_pages) - 1; > + > + if (max_addr >> MAX_PHYSMEM_BITS) { > + const u64 max_allowed = (1ull << (MAX_PHYSMEM_BITS + > 1)) - 1; > + WARN(1, > + "Hotplugged memory exceeds maximum addressable > address, range=%#lx-%#lx, maximum=%#lx\n", Gah, these should all be %#llx. > + PFN_PHYS(pfn), max_addr, max_allowed); > + return -E2BIG; > + } > + > + return 0; > +} > + > /* > * Reasonably generic function for adding memory. It is > * expected that archs that support memory hotplug will > @@ -291,6 +307,10 @@ int __ref __add_pages(int nid, unsigned long > pfn, unsigned long nr_pages, > unsigned long nr, start_sec, end_sec; > struct vmem_altmap *altmap = restrictions->altmap; > > + err = check_hotplug_memory_addressable(pfn, nr_pages); > + if (err) > + return err; > + > if (altmap) { > /* > * Validate altmap is within bounds of the total > request