Re: [PATCH v3 10/10] crypto: safexcel - zeroize crypto_aes_ctx with __cleanup(aes_zeroize_ctx)

[Antoine Tenart]

On Wed, Aug 05, 2026 at 01:57:48PM +0200, Thomas Huth wrote:
> 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.
> 
> Signed-off-by: Thomas Huth <thuth@xxxxxxxxxx>

Acked-by: Antoine Tenart <atenart@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 e94686490bb27..50e8792b399de 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
>