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_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 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 D1D9AC3A5A2 for ; Tue, 10 Sep 2019 07:45:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A55302084D for ; Tue, 10 Sep 2019 07:45:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2393552AbfIJHpw (ORCPT ); Tue, 10 Sep 2019 03:45:52 -0400 Received: from mx1.redhat.com ([209.132.183.28]:50850 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728157AbfIJHpw (ORCPT ); Tue, 10 Sep 2019 03:45:52 -0400 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 88B9BC05AA58; Tue, 10 Sep 2019 07:45:51 +0000 (UTC) Received: from [10.36.117.199] (ovpn-117-199.ams2.redhat.com [10.36.117.199]) by smtp.corp.redhat.com (Postfix) with ESMTP id 7FDFD5D9C9; Tue, 10 Sep 2019 07:45:48 +0000 (UTC) Subject: Re: [PATCH 1/2] memory_hotplug: Add a bounds check to check_hotplug_memory_range() To: Alastair D'Silva , alastair@d-silva.org Cc: Andrew Morton , Oscar Salvador , Michal Hocko , Pavel Tatashin , Wei Yang , Dan Williams , Qian Cai , Jason Gunthorpe , Logan Gunthorpe , Ira Weiny , linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20190910025225.25904-1-alastair@au1.ibm.com> <20190910025225.25904-2-alastair@au1.ibm.com> From: David Hildenbrand Openpgp: preference=signencrypt Autocrypt: addr=david@redhat.com; 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Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <20190910025225.25904-2-alastair@au1.ibm.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.32]); Tue, 10 Sep 2019 07:45:51 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 10.09.19 04:52, 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"). > > Signed-off-by: Alastair D'Silva > --- > include/linux/memory_hotplug.h | 1 + > mm/memory_hotplug.c | 19 ++++++++++++++++++- > 2 files changed, 19 insertions(+), 1 deletion(-) > > diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h > index f46ea71b4ffd..bc477e98a310 100644 > --- a/include/linux/memory_hotplug.h > +++ b/include/linux/memory_hotplug.h > @@ -110,6 +110,7 @@ extern void __online_page_increment_counters(struct page *page); > extern void __online_page_free(struct page *page); > > extern int try_online_node(int nid); > +int check_hotplug_memory_addressable(u64 start, u64 size); > > extern int arch_add_memory(int nid, u64 start, u64 size, > struct mhp_restrictions *restrictions); > diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c > index c73f09913165..3c5428b014f9 100644 > --- a/mm/memory_hotplug.c > +++ b/mm/memory_hotplug.c > @@ -1030,6 +1030,23 @@ int try_online_node(int nid) > return ret; > } > > +#ifndef MAX_POSSIBLE_PHYSMEM_BITS > +#ifdef MAX_PHYSMEM_BITS > +#define MAX_POSSIBLE_PHYSMEM_BITS MAX_PHYSMEM_BITS > +#endif > +#endif > + I think using MAX_POSSIBLE_PHYSMEM_BITS bits is wrong. You should use MAX_PHYSMEM_BITS. E.g. on x86_64, MAX_POSSIBLE_PHYSMEM_BITS is 52, while MAX_PHYSMEM_BITS is (pgtable_l5_enabled() ? 52 : 46) - so MAX_PHYSMEM_BITS depends on the actual HW. > +int check_hotplug_memory_addressable(u64 start, u64 size) > +{ > +#ifdef MAX_POSSIBLE_PHYSMEM_BITS > + if ((start + size - 1) >> MAX_POSSIBLE_PHYSMEM_BITS) > + return -E2BIG; > +#endif > + > + return 0; > +} > +EXPORT_SYMBOL_GPL(check_hotplug_memory_addressable); > + > static int check_hotplug_memory_range(u64 start, u64 size) > { > /* memory range must be block size aligned */ > @@ -1040,7 +1057,7 @@ static int check_hotplug_memory_range(u64 start, u64 size) > return -EINVAL; > } > > - return 0; > + return check_hotplug_memory_addressable(start, size); > } > > static int online_memory_block(struct memory_block *mem, void *arg) > -- Thanks, David / dhildenb