[PATCH 4.14 143/193] libnvdimm, region : make resource attribute only readable by root

[Greg Kroah-Hartman]

4.14-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Dan Williams <dan.j.williams@xxxxxxxxx>

commit b8ff981f88df03c72a4de2f6eaa9ce447a10ac03 upstream.

For the same reason that /proc/iomem returns 0's for non-root readers
and acpi tables are root-only, make the 'resource' attribute for region
devices only readable by root. Otherwise we disclose physical address
information.

Fixes: 802f4be6feee ("libnvdimm: Add 'resource' sysfs attribute to regions")
Cc: Dave Jiang <dave.jiang@xxxxxxxxx>
Cc: Johannes Thumshirn <jthumshirn@xxxxxxx>
Reported-by: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/nvdimm/region_devs.c |    8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

--- a/drivers/nvdimm/region_devs.c
+++ b/drivers/nvdimm/region_devs.c
@@ -562,8 +562,12 @@ static umode_t region_visible(struct kob
 	if (!is_nd_pmem(dev) && a == &dev_attr_badblocks.attr)
 		return 0;
 
-	if (!is_nd_pmem(dev) && a == &dev_attr_resource.attr)
-		return 0;
+	if (a == &dev_attr_resource.attr) {
+		if (is_nd_pmem(dev))
+			return 0400;
+		else
+			return 0;
+	}
 
 	if (a == &dev_attr_deep_flush.attr) {
 		int has_flush = nvdimm_has_flush(nd_region);