• Journal of the Korea Institute of Information Security & Cryptology
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• v.33 no.5
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• pp.775-785
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• 2023

As processor technology advances, it has accelerated ISA extensions and increased the complexity of micro-architectures, leading to a continued rise in the importance of processor validation techniques. Recently, various fuzzing techniques have been introduced to discover undocumented instructions, and this study highlights the shortcomings of existing undocumented instruction fuzzing techniques and presents our observation on error cases in the latest processors from Intel and AMD. In particular, we analyzes the causes of false positives resulting from the fuzzer incorrectly judging CPU instruction length and proposes the length determination technique based on instruction execution information to improve accuracy.