ACPI: x86: s2idle: Catch multiple ACPI_TYPE_PACKAGE objects

If a badly constructed firmware includes multiple `ACPI_TYPE_PACKAGE`
objects while evaluating the AMD LPS0 _DSM, there will be a memory
leak.  Explicitly guard against this.

Suggested-by: Bjorn Helgaas <helgaas@kernel.org>
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/acpi/x86/s2idle.c

@@ -113,6 +113,12 @@ static void lpi_device_get_constraints_amd(void)
 		union acpi_object *package = &out_obj->package.elements[i];
 
 		if (package->type == ACPI_TYPE_PACKAGE) {
+			if (lpi_constraints_table) {
+				acpi_handle_err(lps0_device_handle,
+						"Duplicate constraints list\n");
+				goto free_acpi_buffer;
+			}
+
 			lpi_constraints_table = kcalloc(package->package.count,
 							sizeof(*lpi_constraints_table),
 							GFP_KERNEL);