Region-Based Deterministic Memory Safety via Pointer Encryption

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Solution Overview

Problem

Existing solutions for memory safety, such as memory tagging and capabilities, face challenges including high overhead, complexity, and lack of deterministic protection, while also being incompatible with legacy software and introducing performance issues.

Innovation Solution

The proposed solution utilizes 64-bit, legacy-compatible pointers, eliminates redundant metadata, and provides deterministic protections by specifying slot sizes for each page, encrypting pointers, checking pointer updates, and verifying memory accesses to prevent out-of-bounds access.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If memory tagging or capabilities are used to provide memory safety, then memory safety protection is improved, but overhead and complexity increase

Engineering Contradiction:

Improvememory safety protectionVSAvoidoverhead and complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges pointer encryption with memory safety enforcement into a unified mechanism. The encryption scheme is integrated with the memory management unit (MMU) and page table structures, combining security and safety functions into existing hardware components rather than adding separate systems.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The encrypted pointer system serves multiple functions: it provides memory safety bounds checking, prevents use-after-free attacks, protects against type confusion, and maintains compatibility with legacy software. A single encryption mechanism addresses multiple memory safety concerns that would otherwise require separate protection systems.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Reliability

If memory tagging or capabilities are used to provide memory safety, then memory safety protection is improved, but performance deteriorates

Engineering Contradiction:

Improvememory safety protectionVSAvoidperformance

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

Memory regions and their encryption parameters are pre-configured in page tables before access occurs. The encryption keys and region boundaries are established in advance during memory allocation and page table setup, eliminating the need for runtime computation of safety parameters during critical memory access paths.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent replaces software-based memory safety checking mechanisms with hardware-enforced encryption and decryption operations in the MMU. Safety checks are performed automatically by the encryption/decryption hardware during memory access, eliminating the need for software interpreters or runtime checkers that would degrade performance.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Reliability

If existing memory safety solutions are implemented, then memory safety is improved, but compatibility with legacy software is lost

Engineering Contradiction:

Improvememory safetyVSAvoidcompatibility with legacy software

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent changes the parameter representation from plain pointers to encrypted pointers, where the encryption scheme is transparent to software. Legacy software continues to use pointers in the conventional way, but the hardware automatically encrypts them during store operations and decrypts them during load operations, maintaining binary compatibility while providing safety.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The MMU encryption/decryption hardware acts as an intermediary between legacy software and the memory safety mechanism. Software operates with conventional pointer representations, while the hardware intermediary automatically performs encryption/decryption and bounds checking, allowing legacy code to run safely without modification.

Inventive Principle:

Principle #24Intermediary (Mediator)

4Reliability

If redundant metadata is stored for memory safety, then memory safety protection is improved, but memory overhead increases

Engineering Contradiction:

Improvememory safety protectionVSAvoidmemory overhead

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

The patent merges safety metadata with existing page table structures and memory management data structures. Region boundaries and encryption parameters are stored in the same structures used for virtual address translation and memory allocation, eliminating duplicate metadata storage.

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS20250068776A1Region-based deterministic memory safety

Publication Date: 2025.02.27 INTEL CORP

AI summary

Methods and apparatus relating to techniques for region-based deterministic memory safety are described. In some embodiment, one or more instructions may be used to encrypt, decrypt, and/or check a pointer to a portion of the data stored in memory. The portion of the data is stored in a first region of the memory. The first region of the memory includes a plurality of identically sized allocation slots. Other embodiments are also disclosed and claimed.