[PATCH] ACPICA: Fix missing check for return value of acpi_ns_get_attached_object()

[Chenyuan Mi]

The acpi_ns_get_attached_object() function may return
NULL, which may cause null pointer deference, and most
other callsites of acpi_ns_get_attached_object() do
Null check. Add Null check for return value of
acpi_ns_get_attached_object().

Found by our static analysis tool.

Signed-off-by: Chenyuan Mi <cymi20@xxxxxxxxxxxx>
---
 drivers/acpi/acpica/exprep.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/acpi/acpica/exprep.c b/drivers/acpi/acpica/exprep.c
index 08196fa17080..d9c006ec1ac8 100644
--- a/drivers/acpi/acpica/exprep.c
+++ b/drivers/acpi/acpica/exprep.c
@@ -431,6 +431,13 @@ acpi_status acpi_ex_prep_field_value(struct acpi_create_field_info *info)
 		obj_desc->field.region_obj =
 		    acpi_ns_get_attached_object(info->region_node);
 
+		if (!obj_desc->field.region_obj) {
+			ACPI_ERROR((AE_INFO,
+				    "Null Region Object during field prep"));
+			acpi_ut_delete_object_desc(obj_desc);
+			return_ACPI_STATUS(AE_AML_INTERNAL);
+		}
+
 		/* Fields specific to generic_serial_bus fields */
 
 		obj_desc->field.access_length = info->access_length;
-- 
2.17.1