ACPICA: Prevent infinite loops when traversing corrupted lists.

This change hardens the ACPICA code to detect circular linked object
lists and prevent an infinite loop if such corruption exists.

Signed-off-by: Bob Moore <robert.moore@intel.com>
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

3 files changed, 32 insertions, 4 deletions

diff --git a/drivers/acpi/acpica/evregion.c b/drivers/acpi/acpica/evregion.c
index e31049b3e9d4..9957297d1580 100644
--- a/drivers/acpi/acpica/evregion.c
+++ b/drivers/acpi/acpica/evregion.c
@@ -314,6 +314,7 @@ acpi_ev_detach_region(union acpi_operand_object *region_obj,
 {
         union acpi_operand_object *handler_obj;
         union acpi_operand_object *obj_desc;
+        union acpi_operand_object *start_desc;
         union acpi_operand_object **last_obj_ptr;
         acpi_adr_space_setup region_setup;
         void **region_context;
@@ -341,6 +342,7 @@ acpi_ev_detach_region(union acpi_operand_object *region_obj,
         /* Find this region in the handler's list */
 
         obj_desc = handler_obj->address_space.region_list;
+        start_desc = obj_desc;
         last_obj_ptr = &handler_obj->address_space.region_list;
 
         while (obj_desc) {
@@ -438,6 +440,15 @@ acpi_ev_detach_region(union acpi_operand_object *region_obj,
 
                 last_obj_ptr = &obj_desc->region.next;
                 obj_desc = obj_desc->region.next;
+
+                /* Prevent infinite loop if list is corrupted */
+
+                if (obj_desc == start_desc) {
+                        ACPI_ERROR((AE_INFO,
+                                    "Circular handler list in region object %p",
+                                    region_obj));
+                        return_VOID;
+                }
         }
 
         /* If we get here, the region was not in the handler's region list */
diff --git a/drivers/acpi/acpica/nsobject.c b/drivers/acpi/acpica/nsobject.c
index 32845b105053..fe54a8c73b8c 100644
--- a/drivers/acpi/acpica/nsobject.c
+++ b/drivers/acpi/acpica/nsobject.c
@@ -222,13 +222,19 @@ void acpi_ns_detach_object(struct acpi_namespace_node *node)
                 }
         }
 
-        /* Clear the entry in all cases */
+        /* Clear the Node entry in all cases */
 
         node->object = NULL;
         if (ACPI_GET_DESCRIPTOR_TYPE(obj_desc) == ACPI_DESC_TYPE_OPERAND) {
+
+                /* Unlink object from front of possible object list */
+
                 node->object = obj_desc->common.next_object;
+
+                /* Handle possible 2-descriptor object */
+
                 if (node->object &&
-                    ((node->object)->common.type != ACPI_TYPE_LOCAL_DATA)) {
+                    (node->object->common.type != ACPI_TYPE_LOCAL_DATA)) {
                         node->object = node->object->common.next_object;
                 }
         }
diff --git a/drivers/acpi/acpica/utdelete.c b/drivers/acpi/acpica/utdelete.c
index ed4cb8683310..a3516de213fa 100644
--- a/drivers/acpi/acpica/utdelete.c
+++ b/drivers/acpi/acpica/utdelete.c
@@ -75,6 +75,7 @@ static void acpi_ut_delete_internal_obj(union acpi_operand_object *object)
         union acpi_operand_object *handler_desc;
         union acpi_operand_object *second_desc;
         union acpi_operand_object *next_desc;
+        union acpi_operand_object *start_desc;
         union acpi_operand_object **last_obj_ptr;
 
         ACPI_FUNCTION_TRACE_PTR(ut_delete_internal_obj, object);
@@ -235,10 +236,11 @@ static void acpi_ut_delete_internal_obj(union acpi_operand_object *object)
                         if (handler_desc) {
                                 next_desc =
                                     handler_desc->address_space.region_list;
+                                start_desc = next_desc;
                                 last_obj_ptr =
                                     &handler_desc->address_space.region_list;
 
-                                /* Remove the region object from the handler's list */
+                                /* Remove the region object from the handler list */
 
                                 while (next_desc) {
                                         if (next_desc == object) {
@@ -247,10 +249,19 @@ static void acpi_ut_delete_internal_obj(union acpi_operand_object *object)
                                                 break;
                                         }
 
-                                        /* Walk the linked list of handler */
+                                        /* Walk the linked list of handlers */
 
                                         last_obj_ptr = &next_desc->region.next;
                                         next_desc = next_desc->region.next;
+
+                                        /* Prevent infinite loop if list is corrupted */
+
+                                        if (next_desc == start_desc) {
+                                                ACPI_ERROR((AE_INFO,
+                                                            "Circular region list in address handler object %p",
+                                                            handler_desc));
+                                                return_VOID;
+                                        }
                                 }
 
                                 if (handler_desc->address_space.handler_flags &