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=-6.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED autolearn=unavailable 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 BB646C31E5B for ; Wed, 19 Jun 2019 16:30:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 950232177B for ; Wed, 19 Jun 2019 16:30:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729494AbfFSQa2 (ORCPT ); Wed, 19 Jun 2019 12:30:28 -0400 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:41332 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726246AbfFSQa2 (ORCPT ); Wed, 19 Jun 2019 12:30:28 -0400 Received: from pps.filterd (m0098396.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.27/8.16.0.27) with SMTP id x5JGSQVq015913 for ; Wed, 19 Jun 2019 12:30:27 -0400 Received: from e06smtp02.uk.ibm.com (e06smtp02.uk.ibm.com [195.75.94.98]) by mx0a-001b2d01.pphosted.com with ESMTP id 2t7qcecnpw-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Wed, 19 Jun 2019 12:30:26 -0400 Received: from localhost by e06smtp02.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! 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Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Wed, 19 Jun 2019 17:30:22 +0100 Received: from b06wcsmtp001.portsmouth.uk.ibm.com (b06wcsmtp001.portsmouth.uk.ibm.com [9.149.105.160]) by b06cxnps3074.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id x5JGULFb59965666 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 19 Jun 2019 16:30:21 GMT Received: from b06wcsmtp001.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 14CA6A4067; Wed, 19 Jun 2019 16:30:21 +0000 (GMT) Received: from b06wcsmtp001.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 97E78A405C; Wed, 19 Jun 2019 16:30:19 +0000 (GMT) Received: from skywalker.linux.ibm.com (unknown [9.85.91.144]) by b06wcsmtp001.portsmouth.uk.ibm.com (Postfix) with ESMTP; Wed, 19 Jun 2019 16:30:19 +0000 (GMT) X-Mailer: emacs 26.2 (via feedmail 11-beta-1 I) From: "Aneesh Kumar K.V" To: Dan Williams , akpm@linux-foundation.org Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org, linux-nvdimm@lists.01.org Subject: Re: [PATCH v10 12/13] libnvdimm/pfn: Fix fsdax-mode namespace info-block zero-fields In-Reply-To: <156092356065.979959.6681003754765958296.stgit@dwillia2-desk3.amr.corp.intel.com> References: <156092349300.979959.17603710711957735135.stgit@dwillia2-desk3.amr.corp.intel.com> <156092356065.979959.6681003754765958296.stgit@dwillia2-desk3.amr.corp.intel.com> Date: Wed, 19 Jun 2019 22:00:18 +0530 MIME-Version: 1.0 Content-Type: text/plain X-TM-AS-GCONF: 00 x-cbid: 19061916-0008-0000-0000-000002F53C2B X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 19061916-0009-0000-0000-0000226258B9 Message-Id: <877e9hk06d.fsf@linux.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-06-19_10:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1906190133 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Dan Williams writes: > At namespace creation time there is the potential for the "expected to > be zero" fields of a 'pfn' info-block to be filled with indeterminate > data. While the kernel buffer is zeroed on allocation it is immediately > overwritten by nd_pfn_validate() filling it with the current contents of > the on-media info-block location. For fields like, 'flags' and the > 'padding' it potentially means that future implementations can not rely > on those fields being zero. > > In preparation to stop using the 'start_pad' and 'end_trunc' fields for > section alignment, arrange for fields that are not explicitly > initialized to be guaranteed zero. Bump the minor version to indicate it > is safe to assume the 'padding' and 'flags' are zero. Otherwise, this > corruption is expected to benign since all other critical fields are > explicitly initialized. > > Note The cc: stable is about spreading this new policy to as many > kernels as possible not fixing an issue in those kernels. It is not > until the change titled "libnvdimm/pfn: Stop padding pmem namespaces to > section alignment" where this improper initialization becomes a problem. > So if someone decides to backport "libnvdimm/pfn: Stop padding pmem > namespaces to section alignment" (which is not tagged for stable), make > sure this pre-requisite is flagged. Don't we need a change like below in this patch? modified drivers/nvdimm/pfn_devs.c @@ -452,10 +452,11 @@ int nd_pfn_validate(struct nd_pfn *nd_pfn, const char *sig) if (memcmp(pfn_sb->parent_uuid, parent_uuid, 16) != 0) return -ENODEV; - if (__le16_to_cpu(pfn_sb->version_minor) < 1) { - pfn_sb->start_pad = 0; - pfn_sb->end_trunc = 0; - } + if ((__le16_to_cpu(pfn_sb->version_minor) < 1) || + (__le16_to_cpu(pfn_sb->version_minor) >= 3)) { + pfn_sb->start_pad = 0; + pfn_sb->end_trunc = 0; + } IIUC we want to force the start_pad and end_truc to zero if the pfn_sb minor version number >= 3. So once we have this patch backported and older kernel finds a pfn_sb with minor version 3, it will ignore the start_pad read from the nvdimm and overwrite that with zero here. This patch doesn't enforce that right? After the next patch we can have values other than 0 in pfn_sb->start_pad? > > Fixes: 32ab0a3f5170 ("libnvdimm, pmem: 'struct page' for pmem") > Cc: > Signed-off-by: Dan Williams > --- > drivers/nvdimm/dax_devs.c | 2 +- > drivers/nvdimm/pfn.h | 1 + > drivers/nvdimm/pfn_devs.c | 18 +++++++++++++++--- > 3 files changed, 17 insertions(+), 4 deletions(-) > > diff --git a/drivers/nvdimm/dax_devs.c b/drivers/nvdimm/dax_devs.c > index 49fc18ee0565..6d22b0f83b3b 100644 > --- a/drivers/nvdimm/dax_devs.c > +++ b/drivers/nvdimm/dax_devs.c > @@ -118,7 +118,7 @@ int nd_dax_probe(struct device *dev, struct nd_namespace_common *ndns) > nvdimm_bus_unlock(&ndns->dev); > if (!dax_dev) > return -ENOMEM; > - pfn_sb = devm_kzalloc(dev, sizeof(*pfn_sb), GFP_KERNEL); > + pfn_sb = devm_kmalloc(dev, sizeof(*pfn_sb), GFP_KERNEL); > nd_pfn->pfn_sb = pfn_sb; > rc = nd_pfn_validate(nd_pfn, DAX_SIG); > dev_dbg(dev, "dax: %s\n", rc == 0 ? dev_name(dax_dev) : ""); > diff --git a/drivers/nvdimm/pfn.h b/drivers/nvdimm/pfn.h > index f58b849e455b..dfb2bcda8f5a 100644 > --- a/drivers/nvdimm/pfn.h > +++ b/drivers/nvdimm/pfn.h > @@ -28,6 +28,7 @@ struct nd_pfn_sb { > __le32 end_trunc; > /* minor-version-2 record the base alignment of the mapping */ > __le32 align; > + /* minor-version-3 guarantee the padding and flags are zero */ > u8 padding[4000]; > __le64 checksum; > }; > diff --git a/drivers/nvdimm/pfn_devs.c b/drivers/nvdimm/pfn_devs.c > index 0f81fc56bbfd..4977424693b0 100644 > --- a/drivers/nvdimm/pfn_devs.c > +++ b/drivers/nvdimm/pfn_devs.c > @@ -412,6 +412,15 @@ static int nd_pfn_clear_memmap_errors(struct nd_pfn *nd_pfn) > return 0; > } > > +/** > + * nd_pfn_validate - read and validate info-block > + * @nd_pfn: fsdax namespace runtime state / properties > + * @sig: 'devdax' or 'fsdax' signature > + * > + * Upon return the info-block buffer contents (->pfn_sb) are > + * indeterminate when validation fails, and a coherent info-block > + * otherwise. > + */ > int nd_pfn_validate(struct nd_pfn *nd_pfn, const char *sig) > { > u64 checksum, offset; > @@ -557,7 +566,7 @@ int nd_pfn_probe(struct device *dev, struct nd_namespace_common *ndns) > nvdimm_bus_unlock(&ndns->dev); > if (!pfn_dev) > return -ENOMEM; > - pfn_sb = devm_kzalloc(dev, sizeof(*pfn_sb), GFP_KERNEL); > + pfn_sb = devm_kmalloc(dev, sizeof(*pfn_sb), GFP_KERNEL); > nd_pfn = to_nd_pfn(pfn_dev); > nd_pfn->pfn_sb = pfn_sb; > rc = nd_pfn_validate(nd_pfn, PFN_SIG); > @@ -694,7 +703,7 @@ static int nd_pfn_init(struct nd_pfn *nd_pfn) > u64 checksum; > int rc; > > - pfn_sb = devm_kzalloc(&nd_pfn->dev, sizeof(*pfn_sb), GFP_KERNEL); > + pfn_sb = devm_kmalloc(&nd_pfn->dev, sizeof(*pfn_sb), GFP_KERNEL); > if (!pfn_sb) > return -ENOMEM; > > @@ -703,11 +712,14 @@ static int nd_pfn_init(struct nd_pfn *nd_pfn) > sig = DAX_SIG; > else > sig = PFN_SIG; > + > rc = nd_pfn_validate(nd_pfn, sig); > if (rc != -ENODEV) > return rc; > > /* no info block, do init */; > + memset(pfn_sb, 0, sizeof(*pfn_sb)); > + > nd_region = to_nd_region(nd_pfn->dev.parent); > if (nd_region->ro) { > dev_info(&nd_pfn->dev, > @@ -760,7 +772,7 @@ static int nd_pfn_init(struct nd_pfn *nd_pfn) > memcpy(pfn_sb->uuid, nd_pfn->uuid, 16); > memcpy(pfn_sb->parent_uuid, nd_dev_to_uuid(&ndns->dev), 16); > pfn_sb->version_major = cpu_to_le16(1); > - pfn_sb->version_minor = cpu_to_le16(2); > + pfn_sb->version_minor = cpu_to_le16(3); > pfn_sb->start_pad = cpu_to_le32(start_pad); > pfn_sb->end_trunc = cpu_to_le32(end_trunc); > pfn_sb->align = cpu_to_le32(nd_pfn->align); > > _______________________________________________ > Linux-nvdimm mailing list > Linux-nvdimm@lists.01.org > https://lists.01.org/mailman/listinfo/linux-nvdimm