Under the monolithic architecture of the Linux kernel, all its components operate within the same address space. Notably, device drivers constitute over half of the kernel codebase yet are particularly prone to bugs. Therefore, exploring vulnerabilities in drivers is critical for ensuring kernel security. Extensive research has been done to fuzz kernel drivers through system calls and hardware interrupts. Through a comprehensive study of the Linux Kernel Device Model, we identified that the execution of device drivers is also influenced by runtime parameters, including device attributes and kernel module parameters. Our analysis reveals that large portions of the uncovered code are masked by these parameters, which are exposed to the userspace through a specialized virtual file system known as sysfs. Furthermore, adjacent devices interconnected within the same device tree also impact drivers' behavior.

The interpreter and the Just-In-Time (JIT) compiler are two core components of modern JavaScript engines, both of which take bytecodes as input. Most bugs in these components are closely related to specific bytecodes. Therefore, effective fuzzing should pay close attention to how bytecode is generated and exercised. However, previous work fails to consider this aspect and instead focuses primarily on the syntactic and semantic validity of test cases. This causes two major issues: 1) certain bytecodes are never exercised during fuzzing; 2) some bytecodes are exercised infrequently. In this paper, we propose BCFuzz, a bytecode-driven fuzzing approach designed to enhance the diversity of generated bytecode and increase testing opportunities for low-frequency bytecodes. Specifically, we introduce a parser-oriented probing technique to identify the necessary conditions for generating specific bytecodes and use this information to enhance the input generation process. To better test low-frequency bytecodes, we propose bytecode-aware seed preservation, scheduling, and mutation strategies. We evaluate BCFuzz on four mainstream JavaScript engines. In 72 hours of testing, BCFuzz discovers 1.73× and 1.67× more bugs than DIE and Fuzzilli, respectively. In total, BCFuzz uncovered 20 previously unknown bugs. Of these, 17 have already been fixed and one has been assigned a CVE. All the discovered bugs are related to bytecodes.