Index: linux-2.6.12-rc4/drivers/acpi/tables/tbxfroot.c
===================================================================
--- linux-2.6.12-rc4.orig/drivers/acpi/tables/tbxfroot.c
+++ linux-2.6.12-rc4/drivers/acpi/tables/tbxfroot.c
@@ -313,7 +313,9 @@
 
 
 cleanup:
-	acpi_os_unmap_memory (rsdt_info->pointer, (acpi_size) rsdt_info->pointer->length);
+	if (rsdt_info->pointer)
+		acpi_os_unmap_memory (rsdt_info->pointer,
+			       	      (acpi_size) rsdt_info->pointer->length);
 	ACPI_MEM_FREE (rsdt_info);
 
 	if (header) {