This work considers the case of system maintenance where systems are already deployed and for which some faults or security issues were not detected during the testing phase. We propose an approach based on control theory that allows for automatic generation of maintenance fixes. This approach disables faulty or vulnerable system functionalities and requires to instrument the system before deployment so that it can later be monitored and interact with a supervisor at runtime. This supervisor ensures some property designed after deployment in order to avoid future executions of faulty or vulnerable system functionalities. This property corresponds to a set of safe behaviors described as a Finite State Machine. The computation of supervisors can be performed automatically, relying on a sound Supervisory Control Theory. We first introduce some basic notions of Supervisory Control theory, then we present and illustrate our approach which also relies on automatic models extraction and instrumentation.