Assembly returns a pointer using malloc

I am just training assembly with a coprocessor. The thing is, I don't know how to return a pointer to my value.

Code in C:

double * distance(float x, float y, float z);

      

        
        
        
      

    

And my assembly code:

    .code

_distance  PROC
    push ebp
    mov ebp, esp

    mov eax, 0
    finit ; some aritmetic
    fldz
    fld dword PTR [ebp + 8]
    fsubp st(1), st(0)
    fmul st(0), st(0) ; 0 - x

    fldz
    fld dword PTR [ebp + 12]
    fsubp st(1), st(0)
    fmul st(0), st(0)

    fldz
    fld dword PTR [ebp + 16]
    fsubp st(1), st(0)
    fmul st(0), st(0)

    faddp st(1), st(0)
    faddp st(1), st(0)

    fsqrt

    push 10 ; first i push 10 bytes for malloc                                       
    call _malloc 
    add esp, 4 
    fstp [eax], st(0) ; and then i want to point to the specific value

    pop ebp
    ret
_distance  ENDP

      

        
        
        
      

    

As far as I know, malloc allocates memory and returns the address in eax. So the only thing I want to know is how to point to the co-op register value and return it.