Checking Memory Safety with Blast

Blast is an automatic verification tool for checking temporal safety properties of C programs. Given a C program and a temporal safety property, Blast statically proves that either the program satisfies the safety property or the program has an execution trace that exhibits a violation of the property. Blast constructs, explores, and refines abstractions of the program state space based on lazy predicate abstraction and interpolation-based predicate discovery. We show how Blast can be used to statically prove memory safety for C programs. We take a two-step approach. First, we use Ccured, a type-based memory safety analyzer, to annotate with run-time checks all program points that cannot be proved memory safe by the type system. Second, we use Blast to remove as many of the run-time checks as possible (by proving that these checks never fail), and to generate for the remaining run-time checks execution traces that witness them fail. Our experience shows that Blast can remove many of the run-time checks added by Ccured and provide useful information to the programmer about many of the remaining checks.