Management device and information processing device

A management device configured to control reading and writing of data as performed by a processing circuit with respect to a first memory and with respect to a nonvolatile memory including a plurality of pages, each of the plurality of pages including a plurality of second areas, the management device comprising:

• a counter memory configured to store a counter table in which, for each of the plurality of pages, a counter value indicating a writing count for the page is stored;
• a management device memory configured to store a management table in which management information for each of a predetermined number of pages that is smaller than the plurality of pages is storable, the management information indicating whether each of a plurality of second areas in a concerned page is in a data-written state or a data-unwritten state;
• and
• circuitry configured to:
• for each of the plurality of pages, assign an access method indicating which of a first access process in which writing and reading is performed with respect to data transferred from the nonvolatile memory to the first memory, and a second access process in which writing and reading is performed directly with respect to data stored in the nonvolatile memory, is to be performed;
• perform the first access process when a write request or a read request is received with respect to a page set to the first access process;
• perform the second access process when a write request or a read request is received with respect to a page set to the second access process;
• in response to writing with respect to the nonvolatile memory, update the counter table;
• detect, by referring to the counter table, writing having a high degree of locality representing writing operation performed to an extent equal to or greater than a reference value, with respect to the same area in a plurality of pages to which the second access process is assigned;
• and
• identify a page under attack in which the writing having the high degree of locality is performed, wherein
• in response to writing of first data in the nonvolatile memory by the second access process,
• when a state of a target second area which represents a second area in which the first data is to be written, the state being specified in the management information regarding a target page representing a page in which the first data is to be written, is the data-unwritten state, the circuitry switches the state to the data-written state, and
• when the state of the target second area as specified in the management information is the data-written state, the circuitry switches a state of the target second area to data-written state, switches states of second areas other than the target second area to the data-unwritten state, and updates the counter value for the target page, and
• the circuitry detects updating of the counter value stored in the counter table, and identifies a page under attack.