dax: refactor deprecated strncpy

`strncpy` is deprecated for use on NUL-terminated destination strings [1].

We should prefer more robust and less ambiguous string interfaces.

`dax_id->dev_name` is expected to be NUL-terminated and has been zero-allocated.

A suitable replacement is `strscpy` [2] due to the fact that it
guarantees NUL-termination on the destination buffer. Moreover, due to
`dax_id` being zero-allocated the padding behavior of `strncpy` is not
needed and a simple 1:1 replacement of strncpy -> strscpy should
suffice.

Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings
Link: https://manpages.debian.org/testing/linux-manual-4.8/strscpy.9.en.html
Link: https://github.com/KSPP/linux/issues/90
Cc: linux-hardening@vger.kernel.org
Signed-off-by: Justin Stitt <justinstitt@google.com>
Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Signed-off-by: Ira Weiny <ira.weiny@intel.com>

diff --git a/drivers/dax/bus.c b/drivers/dax/bus.c
index 0ee96e6fc42658ac617f7e4c163c1781e9611491..1659b787b65f55ba885b728597625c56af7aeff2 100644 (file)
--- a/drivers/dax/bus.c
+++ b/drivers/dax/bus.c
@@ -103,7 +103,7 @@ static ssize_t do_id_store(struct device_driver *drv, const char *buf,
                if (action == ID_ADD) {
                        dax_id = kzalloc(sizeof(*dax_id), GFP_KERNEL);
                        if (dax_id) {
-                               strncpy(dax_id->dev_name, buf, DAX_NAME_LEN);
+                               strscpy(dax_id->dev_name, buf, DAX_NAME_LEN);
                                list_add(&dax_id->list, &dax_drv->ids);
                        } else
                                rc = -ENOMEM;