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arXiv · 2502.06609

Automatic ISA analysis for Secure Context Switching

Neelu S. Kalani·Thomas Bourgeat·Guerney D. H. Hunt·Wojciech Ozga
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Abstract

Instruction set architectures are complex, with hundreds of registers and instructions that can modify dozens of them during execution, variably on each instance. Prose-style ISA specifications struggle to capture these intricacies of the ISAs, where often the important details about a single register are spread out across hundreds of pages of documentation. Ensuring that all ISA-state is swapped in context switch implementations of privileged software requires meticulous examination of these pages. This manual process is tedious and error-prone. We propose a tool called Sailor that leverages machine-readable ISA specifications written in Sail to automate this task. Sailor determines the ISA-state necessary to swap during the context switch using the data collected from Sail and a novel algorithm to classify ISA-state as security-sensitive. Using Sailor's output, we identify three different classes of mishandled ISA-state across four open-source confidential computing systems. We further reveal five distinct security vulnerabilities that can be exploited using the mishandled ISA-state. This research exposes an often overlooked attack surface that stems from mishandled ISA-state, enabling unprivileged adversaries to exploit system vulnerabilities.

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Neelu S. Kalani, Thomas Bourgeat, Guerney D. H. Hunt, Wojciech Ozga. 2025-02-10. Automatic ISA analysis for Secure Context Switching. https://arxiv.org/abs/2502.06609

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