nfit, libnvdimm: fix interleave set cookie calculation

The interleave-set cookie is a sum that sanity checks the composition of
an interleave set has not changed from when the namespace was initially
created.  The checksum is calculated by sorting the DIMMs by their
location in the interleave-set. The comparison for the sort must be
64-bit wide, not byte-by-byte as performed by memcmp() in the broken
case.

Fix the implementation to accept correct cookie values in addition to
the Linux "memcmp" order cookies, but only allow correct cookies to be
generated going forward. It does mean that namespaces created by
third-party-tooling, or created by newer kernels with this fix, will not
validate on older kernels. However, there are a couple mitigating
conditions:

    1/ platforms with namespace-label capable NVDIMMs are not widely
       available.

    2/ interleave-sets with a single-dimm are by definition not affected
       (nothing to sort). This covers the QEMU-KVM NVDIMM emulation case.

The cookie stored in the namespace label will be fixed by any write the
namespace label, the most straightforward way to achieve this is to
write to the "alt_name" attribute of a namespace in sysfs.

Cc: <stable@vger.kernel.org>
Fixes: eaf961536e16 ("libnvdimm, nfit: add interleave-set state-tracking infrastructure")
Reported-by: Nicholas Moulin <nicholas.w.moulin@linux.intel.com>
Tested-by: Nicholas Moulin <nicholas.w.moulin@linux.intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

1 files changed, 14 insertions, 4 deletions

diff --git a/drivers/nvdimm/namespace_devs.c b/drivers/nvdimm/namespace_devs.c
index ce3e8dfa10ad..1b481a5fb966 100644
--- a/drivers/nvdimm/namespace_devs.c
+++ b/drivers/nvdimm/namespace_devs.c
@@ -1700,6 +1700,7 @@ static int select_pmem_id(struct nd_region *nd_region, u8 *pmem_id)
 struct device *create_namespace_pmem(struct nd_region *nd_region,
 		struct nd_namespace_label *nd_label)
 {
+	u64 altcookie = nd_region_interleave_set_altcookie(nd_region);
 	u64 cookie = nd_region_interleave_set_cookie(nd_region);
 	struct nd_label_ent *label_ent;
 	struct nd_namespace_pmem *nspm;
@@ -1718,7 +1719,11 @@ struct device *create_namespace_pmem(struct nd_region *nd_region,
 	if (__le64_to_cpu(nd_label->isetcookie) != cookie) {
 		dev_dbg(&nd_region->dev, "invalid cookie in label: %pUb\n",
 				nd_label->uuid);
-		return ERR_PTR(-EAGAIN);
+		if (__le64_to_cpu(nd_label->isetcookie) != altcookie)
+			return ERR_PTR(-EAGAIN);
+
+		dev_dbg(&nd_region->dev, "valid altcookie in label: %pUb\n",
+				nd_label->uuid);
 	}
 
 	nspm = kzalloc(sizeof(*nspm), GFP_KERNEL);
@@ -1733,9 +1738,14 @@ struct device *create_namespace_pmem(struct nd_region *nd_region,
 	res->name = dev_name(&nd_region->dev);
 	res->flags = IORESOURCE_MEM;
 
-	for (i = 0; i < nd_region->ndr_mappings; i++)
-		if (!has_uuid_at_pos(nd_region, nd_label->uuid, cookie, i))
-			break;
+	for (i = 0; i < nd_region->ndr_mappings; i++) {
+		if (has_uuid_at_pos(nd_region, nd_label->uuid, cookie, i))
+			continue;
+		if (has_uuid_at_pos(nd_region, nd_label->uuid, altcookie, i))
+			continue;
+		break;
+	}
+
 	if (i < nd_region->ndr_mappings) {
 		struct nvdimm_drvdata *ndd = to_ndd(&nd_region->mapping[i]);