ACPICA: Harden _PRT repair code; check for minimum package length.

This change prevents a fault during the repair by checking up
front if the _PRT subpackage contains the minimum number of
elements (4).

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>

1 files changed, 7 insertions, 1 deletions

diff --git a/drivers/acpi/acpica/nsrepair2.c b/drivers/acpi/acpica/nsrepair2.c
index 53b4b42a13f2..c57cd4aa357d 100644
--- a/drivers/acpi/acpica/nsrepair2.c
+++ b/drivers/acpi/acpica/nsrepair2.c
@@ -611,6 +611,7 @@ acpi_ns_repair_PRT(struct acpi_evaluate_info *info,
         union acpi_operand_object **top_object_list;
         union acpi_operand_object **sub_object_list;
         union acpi_operand_object *obj_desc;
+        union acpi_operand_object *sub_package;
         u32 element_count;
         u32 index;
 
@@ -620,7 +621,12 @@ acpi_ns_repair_PRT(struct acpi_evaluate_info *info,
         element_count = package_object->package.count;
 
         for (index = 0; index < element_count; index++) {
-                sub_object_list = (*top_object_list)->package.elements;
+                sub_package = *top_object_list;
+                sub_object_list = sub_package->package.elements;
+
+                if (sub_package->package.count < 4) {   /* Minimum required element count */
+                        return (AE_OK);
+                }
 
                 /*
                  * If the BIOS has erroneously reversed the _PRT source_name (index 2)