Mining and checking paired functions in device drivers using characteristic fault injection

Context Device drivers often call specific kernel interface functions in pairs to allocate and release resources, and these functions can be called as paired functions. But due to poor documentation and carelessness, developers sometimes misuse paired functions in drivers, which causes resource-usage violations. Objective Many dynamic approaches have been proposed to mine API rules and check resource usage for user-mode applications, but they are rarely applied to kernel-mode device drivers due to their designs. Meanwhile, most existing dynamic approaches lack systematic mechanisms to cover error handling code, which limits their availability and scalability. Our goal is to improve dynamic analysis to solve these problems. Method In this paper, we propose PairCheck, a novel approach for mining and checking paired functions in device drivers, using three techniques. Firstly, we design a characteristic fault injection framework to generate test cases, which simulates occasional errors and covers most error handling code with little effort. Secondly, complete runtime information is recorded through call interception during test-case execution. Thirdly, we mine and check paired functions based on collected runtime information, name patterns and statistical analysis. Result To validate the availability of PairCheck, we evaluate it on 11 Linux Ethernet card drivers. PairCheck mines 37 and 43 real paired functions in Linux 3.1.1 and 3.17.2, respectively. With these mined paired functions, it finds 10 violations in Linux 3.1.1 which have been fixed in 3.17.2, and 35 new violations in 3.17.2. The replies from developers indicate the false positive rate is low. Compared to normal execution, code coverage increases by 8.3% on average. Conclusion Our work shows that it is possible to precisely mine API rules of resource usage by using characteristic fault injection. The mined rules are useful for improving the reliability of device drivers.