[PATCH 0/3] crypto: replace memset by memzero_explicit

[PATCH 0/3] crypto: replace memset by memzero_explicit

[Kai Ye]

 use memzero_explicit instead of memset to clear sensitive data,
 such as buffer or key.

Kai Ye (3):
  crypto: atmel - use memzero_explicit() for clearing data
  crypto: qce - use memzero_explicit() for clearing data
  crypto: stm32 - use memzero_explicit() for clearing data

 drivers/crypto/atmel-sha.c        | 2 +-
 drivers/crypto/qce/sha.c          | 1 +
 drivers/crypto/stm32/stm32-cryp.c | 2 +-
 3 files changed, 3 insertions(+), 2 deletions(-)

-- 
2.8.1

[PATCH 1/3] crypto: atmel - use memzero_explicit() for clearing data

[Kai Ye]

use memzero_explicit instead of memset to clear sensitive data, such as key.

Signed-off-by: Kai Ye <yekai13@huawei.com>
---
 drivers/crypto/atmel-sha.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/crypto/atmel-sha.c b/drivers/crypto/atmel-sha.c
index 352d80c..4a08b2a 100644
--- a/drivers/crypto/atmel-sha.c
+++ b/drivers/crypto/atmel-sha.c
@@ -1622,7 +1622,7 @@ static inline void atmel_sha_hmac_key_init(struct atmel_sha_hmac_key *hkey)
 static inline void atmel_sha_hmac_key_release(struct atmel_sha_hmac_key *hkey)
 {
 	kfree(hkey->keydup);
-	memset(hkey, 0, sizeof(*hkey));
+	memzero_explicit(hkey, sizeof(*hkey));
 }
 
 static inline int atmel_sha_hmac_key_set(struct atmel_sha_hmac_key *hkey,
-- 
2.8.1

[PATCH 2/3] crypto: qce - use memzero_explicit() for clearing data

[Kai Ye]

use memzero_explicit instead of memset to clear sensitive data.

Signed-off-by: Kai Ye <yekai13@huawei.com>
---
 drivers/crypto/qce/sha.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/crypto/qce/sha.c b/drivers/crypto/qce/sha.c
index 61c418c..cb9b3da 100644
--- a/drivers/crypto/qce/sha.c
+++ b/drivers/crypto/qce/sha.c
@@ -415,6 +415,7 @@ static int qce_ahash_hmac_setkey(struct crypto_ahash *tfm, const u8 *key,
 
 	ret = crypto_wait_req(crypto_ahash_digest(req), &wait);
 
+	memzero_explicit(buf, keylen + QCE_MAX_ALIGN_SIZE);
 	kfree(buf);
 err_free_req:
 	ahash_request_free(req);
-- 
2.8.1

[PATCH 3/3] crypto: stm32 - use memzero_explicit() for clearing data

[Kai Ye]

use memzero_explicit instead of memset to clear sensitive data

Signed-off-by: Kai Ye <yekai13@huawei.com>
---
 drivers/crypto/stm32/stm32-cryp.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/crypto/stm32/stm32-cryp.c b/drivers/crypto/stm32/stm32-cryp.c
index 2a479317..c4297e80 100644
--- a/drivers/crypto/stm32/stm32-cryp.c
+++ b/drivers/crypto/stm32/stm32-cryp.c
@@ -675,7 +675,7 @@ static void stm32_cryp_finish_req(struct stm32_cryp *cryp, int err)
 		crypto_finalize_skcipher_request(cryp->engine, cryp->req,
 						   err);
 
-	memset(cryp->ctx->key, 0, cryp->ctx->keylen);
+	memzero_explicit(cryp->ctx->key, cryp->ctx->keylen);
 }
 
 static int stm32_cryp_cpu_start(struct stm32_cryp *cryp)
-- 
2.8.1

Re: [PATCH 0/3] crypto: replace memset by memzero_explicit

[Herbert Xu]

On Fri, Mar 26, 2021 at 09:20:45AM +0800, Kai Ye wrote:
>  use memzero_explicit instead of memset to clear sensitive data,
>  such as buffer or key.

Does this fix a real issue? If not then it's just unnecessary
churn.

Thanks,
-- 
Email: Herbert Xu <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt