KASAN @ linux kernel

Posted on by lechuck park

From Gemini with some prompting
The image you provided depicts a diagram illustrating the operation of Kernel Address Sanitizer (KASAN) in the Linux kernel. KASAN is a memory sanitizer tool that aims to detect memory corruption errors, particularly those related to out-of-bounds reads/writes and use-after-free vulnerabilities.

Key Elements of the Diagram:

  1. Memory Accessing: This section represents the various ways in which memory is accessed within the kernel. It includes both valid and invalid access patterns.
  2. For All Memory: This indicates that KASAN monitors memory accesses for all allocated memory regions, regardless of their purpose or usage.
  3. Shadow Memory: This represents a dedicated memory space, typically 1/8th of the total physical memory, allocated by KASAN to store information about memory accesses.
  4. Violation Detection: This section highlights the core function of KASAN, which is to detect and report invalid memory access attempts.
  5. Use-after-free Detection: This specifically refers to KASAN’s ability to identify attempts to access memory regions that have already been freed, preventing potential memory corruption issues.
  6. Out-of-Bounds Read/Write: This emphasizes KASAN’s capability to detect memory accesses that exceed the boundaries of the allocated memory regions, safeguarding against buffer overflows and other memory-related vulnerabilities.

Overall Interpretation:

The diagram effectively illustrates the fundamental concept of KASAN: monitoring memory accesses, maintaining a shadow memory space for access information, and detecting invalid access patterns to prevent memory corruption errors.

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Published by lechuck park

AI Infrastructure Architect & Technical Visualizer "Complex Systems, Simplified. I translate massive AI infrastructure into visual intelligence." I love to learn computer tech and help people by the digital.

One thought on “KASAN @ linux kernel”

  1. [ From Claude with some prompting ]

    This image illustrates the working of KASAN (Kernel Address Sanitizer) in the Linux kernel. KASAN is a kernel technology that detects and prevents memory access errors.

    For all memory accesses, data is first loaded into RAM. The memory is then split into pages at the unit level and sampled randomly or at a fixed ratio. This sampling is done in parallel processing.

    The sampled data is mapped to a shadow memory region using a multi-layer hash table. The shadow memory is a separate memory space allocated at 1/8th of the main memory size and is configurable. This shadow memory is dynamically allocated and deallocated as needed.

    KASAN continuously monitors for memory violations such as Use-after-Free, Out-of-Bounds Read/Write. If any violations are detected, appropriate actions can be taken.

    Overall, KASAN is a kernel-level memory protection mechanism that effectively finds and prevents memory-related bugs by employing techniques like sampling, hash tables, and shadow memory mapping.

    It utilizes dynamic memory allocation (ZIP, zlib/bzip2/LZO) for the shadow memory region to optimize memory usage and performance. Memory violation detection is a critical feature of KASAN to ensure memory safety and stability within the Linux kernel.

    (!) Claude gave the best result among chatGPT, gemini, copilot for my diagram-like pages.

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