P11-kit: stack exhaustion via unbounded recursion in rpc attribute parsing

A flaw was found in p11-kit. The RPC message attribute parsing functions p11_rpc_message_get_attribute() and p11_rpc_message_get_attribute_array_value() form a mutually-recursive call chain with no recursion depth limit when processing nested CKA_WRAP_TEMPLATE, CKA_UNWRAP_TEMPLATE, and CKA_DERIVE_TEMPLATE attributes. An unauthenticated attacker with local access to the p11-kit RPC Unix domain socket can send a specially crafted request with deeply nested template attributes, causing stack exhaustion and crashing the p11-kit server process and its dependent services.