crypto: aead,cipher - zeroize key buffer after use

I.G 9.7.B for FIPS 140-3 specifies that variables temporarily holding
cryptographic information should be zeroized once they are no longer
needed. Accomplish this by using kfree_sensitive for buffers that
previously held the private key.
Signed-off-by: Hailey Mothershead <hailmo@amazon.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

crypto/aead.c

@@ -36,8 +36,7 @@ static int setkey_unaligned(struct crypto_aead *tfm, const u8 *key,
 	alignbuffer = (u8 *)ALIGN((unsigned long)buffer, alignmask + 1);
 	memcpy(alignbuffer, key, keylen);
 	ret = crypto_aead_alg(tfm)->setkey(tfm, alignbuffer, keylen);
-	memset(alignbuffer, 0, keylen);
-	kfree(buffer);
+	kfree_sensitive(buffer);
 	return ret;
 }
 

crypto/cipher.c

@@ -34,8 +34,7 @@ static int setkey_unaligned(struct crypto_cipher *tfm, const u8 *key,
 	alignbuffer = (u8 *)ALIGN((unsigned long)buffer, alignmask + 1);
 	memcpy(alignbuffer, key, keylen);
 	ret = cia->cia_setkey(crypto_cipher_tfm(tfm), alignbuffer, keylen);
-	memset(alignbuffer, 0, keylen);
-	kfree(buffer);
+	kfree_sensitive(buffer);
 	return ret;
 
 }