mac802154: llsec: fix return value check in llsec_key_alloc()

In case of error, the functions crypto_alloc_aead() and crypto_alloc_blkcipher()
returns ERR_PTR() and never returns NULL. The NULL test in the return value check
should be replaced with IS_ERR().
Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Signed-off-by: Alexander Aring <alex.aring@gmail.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

net/mac802154/llsec.c

@@ -134,7 +134,7 @@ llsec_key_alloc(const struct ieee802154_llsec_key *template)
 	for (i = 0; i < ARRAY_SIZE(key->tfm); i++) {
 		key->tfm[i] = crypto_alloc_aead("ccm(aes)", 0,
 						CRYPTO_ALG_ASYNC);
-		if (!key->tfm[i])
+		if (IS_ERR(key->tfm[i]))
 			goto err_tfm;
 		if (crypto_aead_setkey(key->tfm[i], template->key,
 				       IEEE802154_LLSEC_KEY_SIZE))
@@ -144,7 +144,7 @@ llsec_key_alloc(const struct ieee802154_llsec_key *template)
 	}
 
 	key->tfm0 = crypto_alloc_blkcipher("ctr(aes)", 0, CRYPTO_ALG_ASYNC);
-	if (!key->tfm0)
+	if (IS_ERR(key->tfm0))
 		goto err_tfm;
 
 	if (crypto_blkcipher_setkey(key->tfm0, template->key,