build_principal_va(krb5_context context, krb5_principal princ,
                   unsigned int rlen, const char *realm, va_list ap)
{
    krb5_error_code retval = 0;
    char *r = NULL;
    krb5_data *data = NULL;
    krb5_int32 count = 0;
    krb5_int32 size = 2;  /* initial guess at needed space */
    char *component = NULL;

     data = malloc(size * sizeof(krb5_data));
     if (!data) { retval = ENOMEM; }
 
    if (!retval)
        r = k5memdup0(realm, rlen, &retval);
 
     while (!retval && (component = va_arg(ap, char *))) {
         if (count == size) {
            krb5_data *new_data = NULL;

            size *= 2;
            new_data = realloc(data, size * sizeof(krb5_data));
            if (new_data) {
                data = new_data;
            } else {
                retval = ENOMEM;
            }
        }

        if (!retval) {
            data[count].length = strlen(component);
            data[count].data = strdup(component);
            if (!data[count].data) { retval = ENOMEM; }
            count++;
        }
    }

    if (!retval) {
        princ->type = KRB5_NT_UNKNOWN;
        princ->magic = KV5M_PRINCIPAL;
        princ->realm = make_data(r, rlen);
        princ->data = data;
        princ->length = count;
        r = NULL;    /* take ownership */
        data = NULL; /* take ownership */
    }

    if (data) {
        while (--count >= 0) {
            free(data[count].data);
        }
        free(data);
    }
    free(r);

    return retval;
}

The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary. This may result in read or write operations on unexpected memory locations that could be linked to other variables, data structures, or internal program data.