[Bug sanitizer/63564] -fsanitize=address obscures access to free memory

[kcc at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63564

--- Comment #2 from Kostya Serebryany <kcc at gcc dot gnu.org> ---
We don't intercept sem_post/sem_wait and don't instrument glibc where they are
implemented. Sadly, the same applies to quite a few other glibc functions. 
In future we may have fully instrumented glibc,
but in the meantime we need to add more interceptors. 
Patches are welcome, 
see https://code.google.com/p/address-sanitizer/wiki/HowToContribute

Most likely sanitizer_common/sanitizer_common_interceptors.inc  will need to be
modified.