Patent ID: 8478960

Claim:
A memory protection method of dividing an address space of a memory into at least two protection regions, and protecting the memory from an unauthorized access to a protection region by a program, the method comprising: a definition step of defining a relation between protection regions; a determination step of, when the relation between the protection regions is an inclusion relation, determining that an included protection region cannot directly access an including protection region and the including protection region can directly access the included protection region; and a memory management step of permitting a direct access for an access for which a direct access is determined to be possible, and prohibiting a direct access for an access for which a direct access is determined to be impossible, wherein in the determination step, determination results for a protection region determined to be able to be directly accessed and for a protection region determined to be unable to be directly accessed are stored in an access authority management table that defines a relation between the protection regions, and in the memory management step, when an access is requested to the protection region determined to be unable to be directly accessed, the protection region determined to be unable to be directly accessed, which is stored in the access authority management table, is changed to a protection region which can be directly accessed, and an indirect access to the protection region determined to be unable to be directly accessed is permitted.