Memory Protection in OS

Memory Protection in OS Visually

Visualization of memory protection in OS. Learn address binding, virtual memory security, buffer overflow protection, and memory isolation with animations.

Memory Protection Access Control Privilege Levels Segmentation Faults Protected Memory Regions Hardware Enforcement Visual Simulation

What is Memory Protection?

Memory protection is a method of controlling memory access rights on a computer system to prevent unauthorized access to memory locations. It is a crucial feature of modern operating systems that ensures the security and stability of the system by preventing processes from accessing memory that does not belong to them.

Memory protection mechanisms work by associating access control attributes with each memory location. These attributes determine which processes or users can read, write, or execute code at that location. When a process attempts to access memory, the system checks these attributes to ensure the access is permitted.

Memory Protection Visualization

Interactive simulation of memory protection mechanisms

Virtual Memory Layout with Protection

1
2
3
4
5
0x00000000 - 0x00FFFFFF
Operating System Kernel
Protected
0x01000000 - 0x01FFFFFF
Process A Memory
User Space
0x02000000 - 0x02FFFFFF
Process B Memory
User Space
0x03000000 - 0x03FFFFFF
Shared Libraries
Read-Only
0x04000000 - 0x04FFFFFF
Stack (Vulnerable to Overflow)
Monitor

Simulation Controls

Memory Protection Concepts

Key mechanisms and techniques used in memory protection

Address Binding

Address binding is the process of mapping logical addresses used by a program to physical addresses in memory. There are three types: compile-time binding, load-time binding, and execution-time binding.

Compile-time Load-time Execution-time

Paging

Paging is a memory management scheme that eliminates external fragmentation and allows the physical address space of a process to be non-contiguous. Each page has protection attributes.

Page Table Frame Number Protection Bits

Segmentation

Segmentation is a memory management technique that supports the user's view of memory. Each segment has a name and length, and can have different protection attributes.

Base Register Limit Register Protection Keys

Memory Protection Keys

Memory protection keys provide a mechanism for protecting memory regions with keys that can be enabled or disabled. This allows for efficient switching between different protection contexts.

Protection Keys Key Registers Access Control

Buffer Overflow Protection

Buffer overflow protection techniques prevent malicious code from being executed by overflowing buffers. Techniques include stack canaries, ASLR, and DEP.

Stack Canaries ASLR DEP/NX Bit

Access Control Lists

Access control lists define which processes or users can access specific memory regions. They provide fine-grained control over memory access permissions.

Read/Write/Execute User/Supervisor Domain-based