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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>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.