[v2] crypto: inside-secure - Zeroize temporary arrays on stack with sensitive data

[PATCH v2] crypto: inside-secure - Zeroize temporary arrays on stack with sensitive data

Posted by Thomas Huth 1 month, 1 week ago

key_tmp[] in safexcel_xcbcmac_setkey() and consts[] / _const[] in
safexcel_cmac_setkey() contain crypto key material that should not
get exposed to the outside once the function is done. Scrub the
arrays with memzero_explicit() to avoid that the data could leak
via the stack.

Reported-by: Sashiko <sashiko-bot@kernel.org>
Link: https://sashiko.dev/#/patchset/20260813134953.979481-1-thuth%40redhat.com
Fixes: 38f21b4bab11f ("crypto: inside-secure - Added support for the AES XCBC ahash")
Fixes: 7a627db9cafdb ("crypto: inside-secure - Added support for the AES-CMAC ahash")
Acked-by: Antoine Tenart <atenart@kernel.org>
Signed-off-by: Thomas Huth <thuth@redhat.com>
---
 v2: Added "Fixes:" and "Reported-by:" tags
 
 drivers/crypto/inside-secure/safexcel_hash.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/crypto/inside-secure/safexcel_hash.c b/drivers/crypto/inside-secure/safexcel_hash.c
index 3402e570d045c..1ae6fbec31298 100644
--- a/drivers/crypto/inside-secure/safexcel_hash.c
+++ b/drivers/crypto/inside-secure/safexcel_hash.c
@@ -1993,6 +1993,7 @@ static int safexcel_xcbcmac_setkey(struct crypto_ahash *tfm, const u8 *key,
 	ret = aes_prepareenckey(ctx->aes,
 				(u8 *)key_tmp + 2 * AES_BLOCK_SIZE,
 				AES_MIN_KEY_SIZE);
+	memzero_explicit(key_tmp, sizeof(key_tmp));
 	if (ret)
 		return ret;
 
@@ -2104,6 +2105,9 @@ static int safexcel_cmac_setkey(struct crypto_ahash *tfm, const u8 *key,
 	}
 	ctx->cbcmac = false;
 
+
+	memzero_explicit(consts, sizeof(consts));
+	memzero_explicit(_const, sizeof(_const));
 	return 0;
 }
 
-- 
2.55.0

Re: [PATCH v2] crypto: inside-secure - Zeroize temporary arrays on stack with sensitive data

Posted by Antoine Tenart 1 month, 1 week ago

On Wed, Aug 19, 2026 at 12:58:36PM +0200, Thomas Huth wrote:
> key_tmp[] in safexcel_xcbcmac_setkey() and consts[] / _const[] in
> safexcel_cmac_setkey() contain crypto key material that should not
> get exposed to the outside once the function is done. Scrub the
> arrays with memzero_explicit() to avoid that the data could leak
> via the stack.
> 
> Reported-by: Sashiko <sashiko-bot@kernel.org>
> Link: https://sashiko.dev/#/patchset/20260813134953.979481-1-thuth%40redhat.com
> Fixes: 38f21b4bab11f ("crypto: inside-secure - Added support for the AES XCBC ahash")
> Fixes: 7a627db9cafdb ("crypto: inside-secure - Added support for the AES-CMAC ahash")
> Acked-by: Antoine Tenart <atenart@kernel.org>
> Signed-off-by: Thomas Huth <thuth@redhat.com>
> ---
>  v2: Added "Fixes:" and "Reported-by:" tags
>  
>  drivers/crypto/inside-secure/safexcel_hash.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/crypto/inside-secure/safexcel_hash.c b/drivers/crypto/inside-secure/safexcel_hash.c
> index 3402e570d045c..1ae6fbec31298 100644
> --- a/drivers/crypto/inside-secure/safexcel_hash.c
> +++ b/drivers/crypto/inside-secure/safexcel_hash.c
> @@ -1993,6 +1993,7 @@ static int safexcel_xcbcmac_setkey(struct crypto_ahash *tfm, const u8 *key,
>  	ret = aes_prepareenckey(ctx->aes,
>  				(u8 *)key_tmp + 2 * AES_BLOCK_SIZE,
>  				AES_MIN_KEY_SIZE);
> +	memzero_explicit(key_tmp, sizeof(key_tmp));
>  	if (ret)
>  		return ret;
>  
> @@ -2104,6 +2105,9 @@ static int safexcel_cmac_setkey(struct crypto_ahash *tfm, const u8 *key,
>  	}
>  	ctx->cbcmac = false;
>  
> +

Sorry, I just noticed there's an extra empty line here.

> +	memzero_explicit(consts, sizeof(consts));
> +	memzero_explicit(_const, sizeof(_const));
>  	return 0;
>  }
>  
> -- 
> 2.55.0
>

Re: [PATCH v2] crypto: inside-secure - Zeroize temporary arrays on stack with sensitive data

Posted by Thomas Huth 1 month, 1 week ago

On 19/08/2026 13.43, Antoine Tenart wrote:
> On Wed, Aug 19, 2026 at 12:58:36PM +0200, Thomas Huth wrote:
>> key_tmp[] in safexcel_xcbcmac_setkey() and consts[] / _const[] in
>> safexcel_cmac_setkey() contain crypto key material that should not
>> get exposed to the outside once the function is done. Scrub the
>> arrays with memzero_explicit() to avoid that the data could leak
>> via the stack.
>>
>> Reported-by: Sashiko <sashiko-bot@kernel.org>
>> Link: https://sashiko.dev/#/patchset/20260813134953.979481-1-thuth%40redhat.com
>> Fixes: 38f21b4bab11f ("crypto: inside-secure - Added support for the AES XCBC ahash")
>> Fixes: 7a627db9cafdb ("crypto: inside-secure - Added support for the AES-CMAC ahash")
>> Acked-by: Antoine Tenart <atenart@kernel.org>
>> Signed-off-by: Thomas Huth <thuth@redhat.com>
>> ---
>>   v2: Added "Fixes:" and "Reported-by:" tags
>>   
>>   drivers/crypto/inside-secure/safexcel_hash.c | 4 ++++
>>   1 file changed, 4 insertions(+)
>>
>> diff --git a/drivers/crypto/inside-secure/safexcel_hash.c b/drivers/crypto/inside-secure/safexcel_hash.c
>> index 3402e570d045c..1ae6fbec31298 100644
>> --- a/drivers/crypto/inside-secure/safexcel_hash.c
>> +++ b/drivers/crypto/inside-secure/safexcel_hash.c
>> @@ -1993,6 +1993,7 @@ static int safexcel_xcbcmac_setkey(struct crypto_ahash *tfm, const u8 *key,
>>   	ret = aes_prepareenckey(ctx->aes,
>>   				(u8 *)key_tmp + 2 * AES_BLOCK_SIZE,
>>   				AES_MIN_KEY_SIZE);
>> +	memzero_explicit(key_tmp, sizeof(key_tmp));
>>   	if (ret)
>>   		return ret;
>>   
>> @@ -2104,6 +2105,9 @@ static int safexcel_cmac_setkey(struct crypto_ahash *tfm, const u8 *key,
>>   	}
>>   	ctx->cbcmac = false;
>>   
>> +
> 
> Sorry, I just noticed there's an extra empty line here.
Oops, that's embarrassing, not sure how I missed that looking at the patch 
multiple times already... Thanks for spotting it, I'll send a v3.

  Thomas