tree 50e428402fdb5e032c90f6cb1cb13a7e707878d3
parent 1eb3c871d35ba9a6820cab421d223d671bb226be
author Dan Williams <dan.j.williams@intel.com> 1553230597 -0700
committer Dan Williams <dan.j.williams@intel.com> 1555620959 -0700

libnvdimm/pfn: Fix fsdax-mode namespace info-block zero-fields

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: <stable@vger.kernel.org>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>