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2c0222b48e
commit7e3e888dfcupstream. 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. Link: http://lkml.kernel.org/r/156092356065.979959.6681003754765958296.stgit@dwillia2-desk3.amr.corp.intel.com Fixes:32ab0a3f51("libnvdimm, pmem: 'struct page' for pmem") Signed-off-by: Dan Williams <dan.j.williams@intel.com> Tested-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> [ppc64] Cc: <stable@vger.kernel.org> Cc: David Hildenbrand <david@redhat.com> Cc: Jane Chu <jane.chu@oracle.com> Cc: Jeff Moyer <jmoyer@redhat.com> Cc: Jérôme Glisse <jglisse@redhat.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Logan Gunthorpe <logang@deltatee.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Mike Rapoport <rppt@linux.ibm.com> Cc: Oscar Salvador <osalvador@suse.de> Cc: Pavel Tatashin <pasha.tatashin@soleen.com> Cc: Toshi Kani <toshi.kani@hpe.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Wei Yang <richardw.yang@linux.intel.com> Cc: Jason Gunthorpe <jgg@mellanox.com> Cc: Christoph Hellwig <hch@lst.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
58 lines
1.7 KiB
C
58 lines
1.7 KiB
C
/*
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* Copyright (c) 2014-2015, Intel Corporation.
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms and conditions of the GNU General Public License,
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* version 2, as published by the Free Software Foundation.
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*
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* This program is distributed in the hope it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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* more details.
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*/
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#ifndef __NVDIMM_PFN_H
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#define __NVDIMM_PFN_H
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#include <linux/types.h>
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#include <linux/mmzone.h>
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#define PFN_SIG_LEN 16
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#define PFN_SIG "NVDIMM_PFN_INFO\0"
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#define DAX_SIG "NVDIMM_DAX_INFO\0"
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struct nd_pfn_sb {
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u8 signature[PFN_SIG_LEN];
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u8 uuid[16];
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u8 parent_uuid[16];
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__le32 flags;
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__le16 version_major;
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__le16 version_minor;
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__le64 dataoff; /* relative to namespace_base + start_pad */
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__le64 npfns;
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__le32 mode;
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/* minor-version-1 additions for section alignment */
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__le32 start_pad;
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__le32 end_trunc;
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/* minor-version-2 record the base alignment of the mapping */
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__le32 align;
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/* minor-version-3 guarantee the padding and flags are zero */
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u8 padding[4000];
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__le64 checksum;
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};
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#ifdef CONFIG_SPARSEMEM
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#define PFN_SECTION_ALIGN_DOWN(x) SECTION_ALIGN_DOWN(x)
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#define PFN_SECTION_ALIGN_UP(x) SECTION_ALIGN_UP(x)
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#else
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/*
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* In this case ZONE_DEVICE=n and we will disable 'pfn' device support,
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* but we still want pmem to compile.
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*/
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#define PFN_SECTION_ALIGN_DOWN(x) (x)
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#define PFN_SECTION_ALIGN_UP(x) (x)
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#endif
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#define PHYS_SECTION_ALIGN_DOWN(x) PFN_PHYS(PFN_SECTION_ALIGN_DOWN(PHYS_PFN(x)))
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#define PHYS_SECTION_ALIGN_UP(x) PFN_PHYS(PFN_SECTION_ALIGN_UP(PHYS_PFN(x)))
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#endif /* __NVDIMM_PFN_H */
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