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[148.163.158.5]) by mx.google.com with ESMTPS id 13si5233378ybj.113.2019.06.12.02.45.59 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 12 Jun 2019 02:45:59 -0700 (PDT) Received-SPF: pass (google.com: domain of aneesh.kumar@linux.ibm.com designates 148.163.158.5 as permitted sender) client-ip=148.163.158.5; Authentication-Results: mx.google.com; spf=pass (google.com: domain of aneesh.kumar@linux.ibm.com designates 148.163.158.5 as permitted sender) smtp.mailfrom=aneesh.kumar@linux.ibm.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=ibm.com Received: from pps.filterd (m0098417.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.27/8.16.0.27) with SMTP id x5C9gI1I058229 for ; Wed, 12 Jun 2019 05:45:59 -0400 Received: from e06smtp01.uk.ibm.com (e06smtp01.uk.ibm.com [195.75.94.97]) by mx0a-001b2d01.pphosted.com with ESMTP id 2t2x1kk2px-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Wed, 12 Jun 2019 05:45:58 -0400 Received: from localhost by e06smtp01.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, 12 Jun 2019 10:45:53 +0100 Received: from d06av26.portsmouth.uk.ibm.com (d06av26.portsmouth.uk.ibm.com [9.149.105.62]) by b06avi18878370.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id x5C9jqEP39190948 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 12 Jun 2019 09:45:52 GMT Received: from d06av26.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id B78B0AE045; Wed, 12 Jun 2019 09:45:52 +0000 (GMT) Received: from d06av26.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 40B8AAE04D; Wed, 12 Jun 2019 09:45:51 +0000 (GMT) Received: from skywalker.linux.ibm.com (unknown [9.124.35.98]) by d06av26.portsmouth.uk.ibm.com (Postfix) with ESMTP; Wed, 12 Jun 2019 09:45:51 +0000 (GMT) X-Mailer: emacs 26.2 (via feedmail 11-beta-1 Q) From: "Aneesh Kumar K.V" To: Dan Williams , akpm@linux-foundation.org Cc: mhocko@suse.com, linux-nvdimm@lists.01.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org, linux-mm@kvack.org, osalvador@suse.de Subject: Re: [PATCH v9 11/12] libnvdimm/pfn: Fix fsdax-mode namespace info-block zero-fields In-Reply-To: <155977193862.2443951.10284714500308539570.stgit@dwillia2-desk3.amr.corp.intel.com> References: <155977186863.2443951.9036044808311959913.stgit@dwillia2-desk3.amr.corp.intel.com> <155977193862.2443951.10284714500308539570.stgit@dwillia2-desk3.amr.corp.intel.com> Date: Wed, 12 Jun 2019 15:11:46 +0530 MIME-Version: 1.0 Content-Type: text/plain X-TM-AS-GCONF: 00 x-cbid: 19061209-4275-0000-0000-000003419E4E X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 19061209-4276-0000-0000-00003851B3FC Message-Id: <87r27zi1id.fsf@linux.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-06-12_05:,, 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-1906120067 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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. > > 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 0453f49dc708..326f02ffca81 100644 > --- a/drivers/nvdimm/dax_devs.c > +++ b/drivers/nvdimm/dax_devs.c > @@ -126,7 +126,7 @@ 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 dde9853453d3..e901e3a3b04c 100644 > --- a/drivers/nvdimm/pfn.h > +++ b/drivers/nvdimm/pfn.h > @@ -36,6 +36,7 @@ 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 01f40672507f..a2406253eb70 100644 > --- a/drivers/nvdimm/pfn_devs.c > +++ b/drivers/nvdimm/pfn_devs.c > @@ -420,6 +420,15 @@ 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; > @@ -565,7 +574,7 @@ 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); > @@ -702,7 +711,7 @@ 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; > > @@ -711,11 +720,14 @@ 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, > @@ -768,7 +780,7 @@ 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); > How will this minor version 3 be used? If we are not having start_pad/end_trunc updated in pfn_sb, how will the older kernel enable these namesapces? Do we need a patch like https://lore.kernel.org/linux-mm/20190604091357.32213-2-aneesh.kumar@linux.ibm.com -aneesh