How to allocate memory and assign it to a variable passed as a parameter in a Fortran subrotine?

Question

I would like to have a subrotine in Fortran that accepts a variable as a parameter. Within this function, memory should be allocated using malloc and assigned to this variable. Afterwards, outside the function, values could be written into this variable (which has allocated memory assigned to it). I have been reading a lot about this subject but so far could not reach to any conclusion or code a solution.