[PATCH v4 10/10] crypto: safexcel - zeroize crypto_aes_ctx with __cleanup(aes_zeroize_ctx)

[Thomas Huth]

From: Thomas Huth <thuth@xxxxxxxxxx>

The code clears the crypto_aes_ctx in most cases already with
memzero_explicit(), but safexcel_skcipher_aesxts_setkey() runs
aes_expandkey() twice, and in case the second call fails, the
context from the first call is leaked.

To fix this issue and to avoid future similar problems, let's use
the new __cleanup(aes_zeroize_ctx) mechanism to make sure that we
always clear the crypto_aes_ctx in all cases.

Acked-by: Antoine Tenart <atenart@xxxxxxxxxx>
Signed-off-by: Thomas Huth <thuth@xxxxxxxxxx>
---
 drivers/crypto/inside-secure/safexcel_cipher.c | 13 ++++---------
 drivers/crypto/inside-secure/safexcel_hash.c   |  3 +--
 2 files changed, 5 insertions(+), 11 deletions(-)

diff --git a/drivers/crypto/inside-secure/safexcel_cipher.c b/drivers/crypto/inside-secure/safexcel_cipher.c
index c331d81ac8a2d..54ab08aea7536 100644
--- a/drivers/crypto/inside-secure/safexcel_cipher.c
+++ b/drivers/crypto/inside-secure/safexcel_cipher.c
@@ -375,7 +375,7 @@ static int safexcel_skcipher_aes_setkey(struct crypto_skcipher *ctfm,
 	struct crypto_tfm *tfm = crypto_skcipher_tfm(ctfm);
 	struct safexcel_cipher_ctx *ctx = crypto_tfm_ctx(tfm);
 	struct safexcel_crypto_priv *priv = ctx->base.priv;
-	struct crypto_aes_ctx aes;
+	struct crypto_aes_ctx aes __cleanup(aes_zeroize_ctx);
 	int ret, i;
 
 	ret = aes_expandkey(&aes, key, len);
@@ -396,7 +396,6 @@ static int safexcel_skcipher_aes_setkey(struct crypto_skcipher *ctfm,
 
 	ctx->key_len = len;
 
-	memzero_explicit(&aes, sizeof(aes));
 	return 0;
 }
 
@@ -1357,7 +1356,7 @@ static int safexcel_skcipher_aesctr_setkey(struct crypto_skcipher *ctfm,
 	struct crypto_tfm *tfm = crypto_skcipher_tfm(ctfm);
 	struct safexcel_cipher_ctx *ctx = crypto_tfm_ctx(tfm);
 	struct safexcel_crypto_priv *priv = ctx->base.priv;
-	struct crypto_aes_ctx aes;
+	struct crypto_aes_ctx aes __cleanup(aes_zeroize_ctx);
 	int ret, i;
 	unsigned int keylen;
 
@@ -1383,7 +1382,6 @@ static int safexcel_skcipher_aesctr_setkey(struct crypto_skcipher *ctfm,
 
 	ctx->key_len = keylen;
 
-	memzero_explicit(&aes, sizeof(aes));
 	return 0;
 }
 
@@ -2537,7 +2535,7 @@ static int safexcel_skcipher_aesxts_setkey(struct crypto_skcipher *ctfm,
 	struct crypto_tfm *tfm = crypto_skcipher_tfm(ctfm);
 	struct safexcel_cipher_ctx *ctx = crypto_tfm_ctx(tfm);
 	struct safexcel_crypto_priv *priv = ctx->base.priv;
-	struct crypto_aes_ctx aes;
+	struct crypto_aes_ctx aes __cleanup(aes_zeroize_ctx);
 	int ret, i;
 	unsigned int keylen;
 
@@ -2585,7 +2583,6 @@ static int safexcel_skcipher_aesxts_setkey(struct crypto_skcipher *ctfm,
 
 	ctx->key_len = keylen << 1;
 
-	memzero_explicit(&aes, sizeof(aes));
 	return 0;
 }
 
@@ -2751,12 +2748,11 @@ static int safexcel_aead_ccm_setkey(struct crypto_aead *ctfm, const u8 *key,
 	struct crypto_tfm *tfm = crypto_aead_tfm(ctfm);
 	struct safexcel_cipher_ctx *ctx = crypto_tfm_ctx(tfm);
 	struct safexcel_crypto_priv *priv = ctx->base.priv;
-	struct crypto_aes_ctx aes;
+	struct crypto_aes_ctx aes __cleanup(aes_zeroize_ctx);
 	int ret, i;
 
 	ret = aes_expandkey(&aes, key, len);
 	if (ret) {
-		memzero_explicit(&aes, sizeof(aes));
 		return ret;
 	}
 
@@ -2785,7 +2781,6 @@ static int safexcel_aead_ccm_setkey(struct crypto_aead *ctfm, const u8 *key,
 	else
 		ctx->hash_alg = CONTEXT_CONTROL_CRYPTO_ALG_XCBC128;
 
-	memzero_explicit(&aes, sizeof(aes));
 	return 0;
 }
 
diff --git a/drivers/crypto/inside-secure/safexcel_hash.c b/drivers/crypto/inside-secure/safexcel_hash.c
index 3402e570d045c..20c17eb09495e 100644
--- a/drivers/crypto/inside-secure/safexcel_hash.c
+++ b/drivers/crypto/inside-secure/safexcel_hash.c
@@ -1905,7 +1905,7 @@ static int safexcel_cbcmac_setkey(struct crypto_ahash *tfm, const u8 *key,
 				 unsigned int len)
 {
 	struct safexcel_ahash_ctx *ctx = crypto_tfm_ctx(crypto_ahash_tfm(tfm));
-	struct crypto_aes_ctx aes;
+	struct crypto_aes_ctx aes __cleanup(aes_zeroize_ctx);
 	int ret, i;
 
 	ret = aes_expandkey(&aes, key, len);
@@ -1928,7 +1928,6 @@ static int safexcel_cbcmac_setkey(struct crypto_ahash *tfm, const u8 *key,
 	}
 	ctx->cbcmac  = true;
 
-	memzero_explicit(&aes, sizeof(aes));
 	return 0;
 }
 
-- 
2.55.0