I think GP confused DLL injection with return to libc.

I see why; in return to libc, which is prevented by ASLR, you are injecting the control of flow into the middle of a DLL(that DLL is libc). The terminology is a little confusing.

meant hooking functions statically or even dynamically with a minimal amount of codegolf'd asm instructions inserted via buffer overflow, and repairing the stack to sneak by stack smashing detecting, but yea, libc is implied in the linux environment