Memóriavédelem

Memóriavédelem, meaning "memory protection" in Hungarian, refers to a set of techniques and mechanisms designed to prevent unintended or malicious access to and modification of computer memory. This is crucial for the stability, security, and integrity of software and the overall operating system.

At its core, memory protection aims to isolate different processes from each other. Each running program is allocated its own virtual address space, and the operating system, with hardware assistance, ensures that one process cannot read from or write to the memory regions allocated to another process. This prevents a bug in one application from crashing the entire system or one malicious program from stealing sensitive data from another.

Common memory protection mechanisms include physical memory mapping, which assigns specific physical memory addresses to processes, and virtual memory, which uses a memory management unit (MMU) to translate virtual addresses used by programs into physical addresses. The MMU enforces access permissions, such as read, write, and execute, for each memory page. If a process attempts an operation that violates these permissions, the MMU triggers a fault, which the operating system handles, often by terminating the offending process.

Beyond process isolation, memory protection also safeguards critical operating system code and data from user-level programs. This prevents user applications from altering the kernel's instructions or data structures, which would be catastrophic for system operation. Techniques like No-Execute (NX) bits or Execute Disable (XD) bits prevent code from being executed from memory regions that are designated only for data, a crucial defense against buffer overflow attacks.