The increasing scale and complexity of software makes the software safety and security critical. Thus more and more research focuses on the development of high-assurance software. Since type system is not expressive enough, the existing research does not touch the verification of infrastructure codes. In this paper, a certified dynamic storage management library is built using Hoare-logic style reasoning at the assembly level with the assistance of a theorem formalization and proof tool called Coq, since Hoare logic is more expressive. This work is a significant application of program verification technique. The experiment shows that program verification can be applied in high-assurance software development.