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

[Thomas Huth]

This issue has been found by the Sashiko bot while reviewing another
patch: 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.

Signed-off-by: Thomas Huth <thuth@xxxxxxxxxx>
---
 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