libnvdimm/namespace: Fix a potential NULL pointer dereference

In case kmemdup fails, the fix goes to blk_err to avoid NULL
pointer dereference.

Signed-off-by: Kangjie Lu <kjlu@umn.edu>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

drivers/nvdimm/namespace_devs.c

@@ -2249,9 +2249,12 @@ static struct device *create_namespace_blk(struct nd_region *nd_region,
 	if (!nsblk->uuid)
 		goto blk_err;
 	memcpy(name, nd_label->name, NSLABEL_NAME_LEN);
-	if (name[0])
+	if (name[0]) {
 		nsblk->alt_name = kmemdup(name, NSLABEL_NAME_LEN,
 				GFP_KERNEL);
+		if (!nsblk->alt_name)
+			goto blk_err;
+	}
 	res = nsblk_add_resource(nd_region, ndd, nsblk,
 			__le64_to_cpu(nd_label->dpa));
 	if (!res)