ctypes: how to make a structure pointer to point to a buffer

[人言落日是天涯，望极天涯不见家]

first, I'm try the POINTER to convesion the pointer type. but failed.

class STUDENT(Structure):
    _fields_ = [('name',  c_int),
                    ('id',   c_int),
                    ('addition',    c_ubyte)]

buffer = c_byte * 1024
student_p = cast(buffer, POINTER(STUDENT))

The parameter of the POINTER must be ctypes type.
How could I attach the buffer pointer to the structure STUDENT ?