ACPICA: Fix to allow aliases within ASL namepaths

Fixes a problem where the use of an alias within a namepath
would result in a not found error or cause the compiler to fault.
Also now allows forward references from the Alias operator itself.
ACPICA BZ 738.

http://www.acpica.org/bugzilla/show_bug.cgi?id=738

Signed-off-by: Bob Moore <robert.moore@intel.com>
Signed-off-by: Lin Ming <ming.m.lin@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>

1 files changed, 4 insertions, 0 deletions

diff --git a/drivers/acpi/namespace/nsaccess.c b/drivers/acpi/namespace/nsaccess.c
index 29c7c271dbb..35b0e46bd09 100644
--- a/drivers/acpi/namespace/nsaccess.c
+++ b/drivers/acpi/namespace/nsaccess.c
@@ -588,6 +588,10 @@ acpi_ns_lookup(union acpi_generic_state *scope_info,
                          * segments).
                          */
                         if (this_node->type == ACPI_TYPE_LOCAL_ALIAS) {
+                                if (!this_node->object) {
+                                        return_ACPI_STATUS(AE_NOT_EXIST);
+                                }
+
                                 if (acpi_ns_opens_scope
                                     (((struct acpi_namespace_node *)this_node->
                                       object)->type)) {