Cryptographic Memory State Tracking for Uninitialized Read Detection
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Solution Overview
Problem
Uninitialized memory reads are difficult to detect and can lead to bugs that are hard to find, as they may not manifest near the allocation or reading but cause issues later, and existing techniques struggle to mitigate intra-object overflows and uninitialized use vulnerabilities.
Innovation Solution
Implement cryptographic integrity checking (ICV) to track the initialization state of memory through the execution of a program, using instructions like InitICV, PreinitICV, and PartInitICV to ensure data is properly initialized before access, and incorporate ICV metadata to enforce integrity checks at various granularities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional memory allocation and access methods are used, then software execution speed is maintained, but uninitialized memory reads occur leading to security vulnerabilities and hard-to-detect bugs
Solution Approach 1:
The system performs preliminary initialization of ICV metadata to a second indicator (uninitialized state) during memory allocation, before any read operations occur. This preliminary action enables the system to detect uninitialized reads by comparing the current ICV state against the expected initialized state, resolving the contradiction by proactively preventing security vulnerabilities while maintaining simple memory access patterns
Solution Approach 2:
The patent introduces ICV (Integrity Check Value) metadata as an intermediary layer between the memory allocator and memory access operations. This intermediary tracks the initialization state of memory regions without requiring changes to the underlying memory allocation mechanisms, enabling detection of uninitialized reads while preserving existing memory management complexity
2Measurement precision
If comprehensive integrity checking is implemented, then detection of uninitialized memory reads improves, but processing overhead and execution time increase
Solution Approach 1:
The system applies integrity checking selectively based on the ICV state indicator. Reads from memory regions marked as uninitialized (second indicator) trigger integrity checks, while reads from initialized regions (first indicator) proceed normally. This local application of quality control achieves high detection precision for vulnerable operations without imposing overhead on all memory accesses, resolving the contradiction between detection accuracy and execution speed
3Measurement precision
If ICV metadata tracking is implemented at fine granularity, then detection precision for partial initializations improves, but memory overhead and complexity increase
Solution Approach 1:
The system implements partial initialization tracking by maintaining ICV metadata only for portions of memory that require monitoring. The ICV state can represent multiple initialization states (fully initialized, partially initialized, uninitialized) allowing precise tracking of initialization progress without requiring separate metadata for every single byte. This partial action approach achieves high detection precision while minimizing the quantity of tracking metadata required
Data Source
AI summary
Examples of instructions to support the recording of memory initialization states as well as several ways to manipulate the states to detect uninitialized memory reads are described. In some examples, execution circuitry to conditionally execute decoded read and write instructions; and integrity check value integrity checking circuitry to determine when decoded read and write instructions associated with an object are allowed to execute based at least in part on integrity check value (ICV) metadata are described.