Is it permissible to use free software on a non-genuine operating system, and is it lawful to benefit from the products resulting from it?

It is permissible to benefit from free software. As for protected software, it is not permissible to infringe upon it or violate the rights of its owners. Whoever infringes upon it is obligated to pay the value of the benefits he caused the owner to miss and the damages incurred by him. As for designs made with free software while using pirated operating systems, it is permissible to benefit from them while guaranteeing the rights of the owners of the infringed software. It is necessary to estimate what the owners of the software have missed, and if it is impossible to know the amount or deliver the right to its owners, it is permissible to give it as charity on their behalf.