[PATCH v5 08/10] crypto: safexcel - Simplify the check for a valid AES key

From: Thomas Huth <[email protected]>

safexcel_aead_setkey() currently uses aes_expandkey() to check for a valid
AES key, but then does not use the crypto_aes_ctx afterwards anymore,
i.e. this is just a wasteful way of checking the key length, and thus
aes_check_keylen() should be used instead.
This also fixes a potential leak of sensitive data via the stack, since
this function forgot to zeroize crypto_aes_ctx before returning to the
caller.

Suggested-by: Antoine Tenart <[email protected]>
Signed-off-by: Thomas Huth <[email protected]>
---
 drivers/crypto/inside-secure/safexcel_cipher.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/crypto/inside-secure/safexcel_cipher.c b/drivers/crypto/inside-secure/safexcel_cipher.c
index a8349b684693e..f07d043c67d45 100644
--- a/drivers/crypto/inside-secure/safexcel_cipher.c
+++ b/drivers/crypto/inside-secure/safexcel_cipher.c
@@ -407,7 +407,6 @@ static int safexcel_aead_setkey(struct crypto_aead *ctfm, const u8 *key,
 	struct safexcel_cipher_ctx *ctx = crypto_tfm_ctx(tfm);
 	struct safexcel_crypto_priv *priv = ctx->base.priv;
 	struct crypto_authenc_keys keys;
-	struct crypto_aes_ctx aes;
 	int err = -EINVAL, i;
 	const char *alg;
 
@@ -438,7 +437,7 @@ static int safexcel_aead_setkey(struct crypto_aead *ctfm, const u8 *key,
 			goto badkey;
 		break;
 	case SAFEXCEL_AES:
-		err = aes_expandkey(&aes, keys.enckey, keys.enckeylen);
+		err = aes_check_keylen(keys.enckeylen);
 		if (unlikely(err))
 			goto badkey;
 		break;
-- 
2.55.0