Golang Array Shuffler

shuffle.go

/*
An array shuffler with good randomness
*/
package main

import (
	"fmt"
	"math/big"
	"crypto/rand"
)

func main() {
	arr := []int{1,2,3,4,5,6,7,8,9}
	shuffle(arr)
	fmt.Println("Shuffled: ", arr)
}

func shuffle(arr []int) error {
	l := len(arr)
	max := big.NewInt(int64(l - 1))
	shuf := make([]int, len(arr))
	copy(shuf, arr)
	for range shuf {
		r, err := rand.Int(rand.Reader, max)
		if err != nil {
			return err
		}
		rn := int(r.Int64())
		n := shuf[rn]
		shuf = append(shuf[:rn], shuf[rn+1:]...)
		shuf = append(shuf, n)		
	}
	copy(arr, shuf)
	return nil
}

Thx!
But it is memoryleaker.