ACPICA: Namespace: Properly null terminate objects detached from a na…

…mespace node

Fixes a bug exposed by an ACPICA unit test around the
acpi_attach_data()/acpi_detach_data() APIs where the failure to null
terminate a detached object led to the creation of a circular linked list
(and infinite looping) when the object is reattached.

Reported in acpica bugzilla #1063

Link: https://bugs.acpica.org/show_bug.cgi?id=1063
Signed-off-by: David E. Box <david.e.box@linux.intel.com>
Signed-off-by: Bob Moore <robert.moore@intel.com>
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Cc: 3.15+ <stable@vger.kernel.org> # 3.15+
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/acpi/acpica/nsobject.c

@@ -239,6 +239,17 @@ void acpi_ns_detach_object(struct acpi_namespace_node *node)
 		}
 	}
 
+	/*
+	 * Detach the object from any data objects (which are still held by
+	 * the namespace node)
+	 */
+
+	if (obj_desc->common.next_object &&
+	    ((obj_desc->common.next_object)->common.type ==
+	     ACPI_TYPE_LOCAL_DATA)) {
+		obj_desc->common.next_object = NULL;
+	}
+
 	/* Reset the node type to untyped */
 
 	node->type = ACPI_TYPE_ANY;