CoreCheck is a very simple tool for Valgrind. It adds no instrumentation to the program's code, and only reports the few kinds of errors detected by Valgrind's core. It is mainly of use for Valgrind's developers for debugging and regression testing. The errors detected are those found by the core when VG_(needs).core_errors is set. These include: Pthread API errors (many; eg. unlocking a non-locked mutex) Silly arguments to malloc() et al (eg. negative size) Invalid file descriptors to blocking syscalls read() and write() Bad signal numbers passed to sigaction() Attempts to install signal handler for SIGKILL or SIGSTOP