A linear stability analysis of the RFX-mod equilibrium profiles is carried out in cylindrical geometry for the m = 1 modes resonant inside the reversal surface (dynamo modes). The screening effect of the passive structures surrounding the plasma is taken into account. The results show that magnetic perturbations appear as linear instabilities in the setting up of the reversed field pinch configuration before the reversal of the edge toroidal magnetic field. Later on the equilibrium profiles are found marginally stable for linear tearing modes and completely stable for ideal modes.