Dnmalloc is an allocator that keeps heap management data separate from the heap itself. As a result, dnmalloc is not vulnerable to corruption of the heap management information by heap buffer overflows or double free errors.
You can download it from the following link: https://packetstormsecurity.com/files/download/68019/dnmalloc-1.0.tar.gz
Source: https://packetstormsecurity.com/files/68019/dnmalloc-1.0.tar.gz.html