dm crypt: wipe keys string immediately after key is set

static int crypt_set_key(struct crypt_config *cc, char *key)

{

	int r = -EINVAL;

	int key_string_len = strlen(key);

	/* The key size may not be changed. */

	if (cc->key_size != (strlen(key) >> 1))

		return -EINVAL;

	if (cc->key_size != (key_string_len >> 1))

		goto out;

	/* Hyphen (which gives a key_size of zero) means there is no key. */

	if (!cc->key_size && strcmp(key, "-"))

		return -EINVAL;

		goto out;

	if (cc->key_size && crypt_decode_key(cc->key, key, cc->key_size) < 0)

		return -EINVAL;

		goto out;

	set_bit(DM_CRYPT_KEY_VALID, &cc->flags);

	return crypt_setkey_allcpus(cc);

	r = crypt_setkey_allcpus(cc);

out:

	/* Hex key string not needed after here, so wipe it. */

	memset(key, '0', key_string_len);

	return r;

}

static int crypt_wipe_key(struct crypt_config *cc)