Verification of webassembly programs

WebAssembly is a new low-level language and compilation target mainly for the web that is already shipped in all major browsers in its minimum viable product version. The current version does not support exception handling, and therefore runtime errors cannot be handled inside the WebAssembly code. Our main contribution of this research is the development of an approach that can detect runtime errors (traps) statically using Skink, a static analysis tool. To detect the possible traps, we: 1. translate WebAssembly (stack machine) into LLVM-IR (register machine), and 2. instrument the resulting code to reduce the problem of detecting traps to a reachability problem. To test our solution, we use C/C++ benchmarks files from SV-COMP compiled into WebAssembly by Emscripten and compare the results against the standard verification process of C/C++ files by Skink. After successfully testing our approach, we apply our tool to verify programs that could abort execution due to runtime errors, detecting the conditions under which the error would occur. Internet browsers could benefit from this approach in the future, as they will execute WebAssembly modules that originate from untrusted sources and possibly with malicious intentions. Our approach would then aid in the early detection of runtime errors of these WebAssembly modules.Macquarie UniversityAgencia Nacional de Investigación e Innovació

The sbt-rats parser generator plugin for Scala (tool paper)

Tools for creating parsers are a key part of a mature language eco-system. Scala has traditionally relied on combinator libraries for defining parsers but being libraries they come with fundamental implementation limitations. An alternative is to use a Java-based parser generator such as ANTLR or Rats! but these tools are quite verbose and not ideal to use with Scala code. We describe our experiences with Scalafocused parser generation that is embodied in our sbt-rats plugin for the Scala Build Tool. At its simplest, sbt-rats provides a bridge to the Rats! parser generator for Java. On top of this bridge, we have a simple grammar definition notation that incorporates annotations for tree construction and pretty-printing. As well as generating a Rats! grammar, sbt-rats can optionally generate case class definitions for the tree structure and a pretty-printer defined using our Kiama language processing library. We explain the sbt-rats grammar notation and describe our positive experiences using it to define grammars for LLVM assembly notation and the SMTLIB input/output language for SMT solvers.4 page(s