Understanding Memory Management, Part 1: C

Avoid as much as you can the C standard lib allocator, go directly to mmap system call with your own allocator if you know you won't use CPU without a MMU.

If you write a library, let the user code install its own allocator.

"malloc" is a weakly-bound symbol that can be overridden, on every system I've used. I don't know if some standard defines it to be weak. Anyway the point is that malloc is not necessarily a call to the C standard library function. It can be anything.

"weakly-bound symbol" implies your a using a complex runtime library/binary format (like ELF).

A portable and clean design for a library is to allow to override the internal allocator via the API (often part of the init function call).

Look at vulkan3D which does many things right and doing this very part right. On the other side, you have some parts of the ALSA lib API which still requires to use the C lib free (may be obsolete though).