iscsi-target: Fix tfc_tpg_nacl_auth_cit configfs length overflow

This patch fixes a potential buffer overflow while processing
iscsi_node_auth input for configfs attributes within NodeACL
tfc_tpg_nacl_auth_cit context.
Signed-off-by: Joern Engel <joern@logfs.org>
Cc: stable@vger.kernel.org
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

drivers/target/iscsi/iscsi_target_configfs.c

@@ -473,7 +473,7 @@ static ssize_t __iscsi_##prefix##_store_##name(				\
 	if (!capable(CAP_SYS_ADMIN))					\
 		return -EPERM;						\
 									\
-	snprintf(auth->name, PAGE_SIZE, "%s", page);			\
+	snprintf(auth->name, sizeof(auth->name), "%s", page);		\
 	if (!strncmp("NULL", auth->name, 4))				\
 		auth->naf_flags &= ~flags;				\
 	else								\