Testing Closed-Source Binary Device Drivers with DDT

DDT is a system for testing closed-source binary device drivers against undesired behaviors, like race conditions, memory errors, resource leaks, etc. One can metaphorically think of it as a pesticide against device driver bugs. DDT combines virtualization with a specialized form of symbolic execution to thoroughly exercise tested drivers; a set of modular dynamic checkers identify bug conditions and produce detailed, executable traces for every path that leads to a failure. These traces can be used to easily reproduce and understand the bugs, thus both proving their existence and helping debug them. We applied DDT to several closed-source Microsoft-certified Windows device drivers and discovered 14 serious new bugs. DDT is easy to use, as it requires no access to source code and no assistance from users. We therefore envision DDT being useful not only to developers and testers, but also to consumers who want to avoid running buggy drivers in their OS kernels

Enabling Sophisticated Analysis of x86 Binaries with RevGen

Current state-of-the-art static analysis tools for binary software operate on ad-hoc intermediate representations (IR) of the machine code. Therefore, even though IRs facilitate program analysis by abstracting away the source language, it is hard to reuse existing implementations of analysis tools in new endeavors. Recently, a new compiler framework — LLVM— has emerged, together with many analysis tools that use its IR. However, these tools rely on a compiler to generate the IR from source code. We propose RevGen, a tool that automatically converts existing binary programs to the standard LLVM IR, making an increasingly large number of static and dynamic analysis frameworks, as well as run-time instrumentation tools, applicable to legacy software. We show the potential of RevGen by converting several programs and device drivers to LLVM and checking the resulting code with off-the-shelf analysis tools

A Formally Verified NAT Stack

Prior work proved a stateful NAT network function to be semantically correct, crash-free, and memory safe. Their toolchain verifies the network function code while assuming the underlying kernel-bypass framework, drivers, operating system, and hardware to be correct. We extend the toolchain to verify the kernel-bypass framework and a NIC driver in the context of the NAT. We uncover bugs in both the framework and the driver. Our code is publicly available

Diagnosys: Automatic Generation of a Debugging Interface to the Linux Kernel

Best Paper awardInternational audienceThe Linux kernel does not export a stable, well-defined kernel interface, complicating the development of kernel-level services, such as device drivers and file systems. While there does exist a set of functions that are exported to external modules, this set of functions frequently changes, and the functions have implicit, ill-documented preconditions. No specific debugging support is provided. We present \textit{Diagnosys}, an approach to automatically constructing a debugging interface for the Linux kernel. First, a designated kernel maintainer ses Diagnosys to identify constraints on the use of the exported functions. Based on this information, developers of kernel services can then use Diagnosys to generate a debugging interface specialized to their code. When a service including this interface is tested, it records information about potential problems. This information is preserved following a kernel crash or hang. Our experiments show that the generated debugging interface provides useful log information and incurs a low performance penalty