Yes I don't want to imply that glibc malloc was the culprit here, but glibc malloc is one of the reasons why certain systems have their own malloc / slab alloca

Yes I don't want to imply that glibc malloc was the culprit here, but glibc malloc is one of the reasons why certain systems have their own malloc / slab allocator / whatever. About the embedded systems, usually you don't try to cover everything, it is often a more valid a approach to have specialized libraries for very resource constrained systems. In the case of OpenSSL I guess the problem is that the implementation was hard enough to force OpenSSL to blend instead. This is where to be able to say "no" is a good idea.