Subject: [PATCH v2 2/2] crypto: Remove unnecessary memzero_explicit()

From: Waiman Long <[email-masked]>
Date: Mon, 13 Apr 2020 18:28:46 -0400

Since kfree_sensitive() will do an implicit memzero_explicit(), there
is no need to call memzero_explicit() before it. Eliminate those
memzero_explicit() and simplify the call sites. For better correctness,
the setting of keylen is also moved down after the key pointer check.

Signed-off-by: Waiman Long <[email-masked]>
---
 .../allwinner/sun8i-ce/sun8i-ce-cipher.c      | 19 +++++-------------
 .../allwinner/sun8i-ss/sun8i-ss-cipher.c      | 20 +++++--------------
 drivers/crypto/amlogic/amlogic-gxl-cipher.c   | 12 +++--------
 drivers/crypto/inside-secure/safexcel_hash.c  |  3 +--
 4 files changed, 14 insertions(+), 40 deletions(-)

diff --git a/drivers/crypto/allwinner/sun8i-ce/sun8i-ce-cipher.c b/drivers/crypto/allwinner/sun8i-ce/sun8i-ce-cipher.c
index aa4e8fdc2b32..8358fac98719 100644
--- a/drivers/crypto/allwinner/sun8i-ce/sun8i-ce-cipher.c
+++ b/drivers/crypto/allwinner/sun8i-ce/sun8i-ce-cipher.c
@@ -366,10 +366,7 @@ void sun8i_ce_cipher_exit(struct crypto_tfm *tfm)
 {
 	struct sun8i_cipher_tfm_ctx *op = crypto_tfm_ctx(tfm);
 
-	if (op->key) {
-		memzero_explicit(op->key, op->keylen);
-		kfree(op->key);
-	}
+	kfree_sensitive(op->key);
 	crypto_free_sync_skcipher(op->fallback_tfm);
 	pm_runtime_put_sync_suspend(op->ce->dev);
 }
@@ -391,14 +388,11 @@ int sun8i_ce_aes_setkey(struct crypto_skcipher *tfm, const u8 *key,
 		dev_dbg(ce->dev, "ERROR: Invalid keylen %u\n", keylen);
 		return -EINVAL;
 	}
-	if (op->key) {
-		memzero_explicit(op->key, op->keylen);
-		kfree(op->key);
-	}
-	op->keylen = keylen;
+	kfree_sensitive(op->key);
 	op->key = kmemdup(key, keylen, GFP_KERNEL | GFP_DMA);
 	if (!op->key)
 		return -ENOMEM;
+	op->keylen = keylen;
 
 	crypto_sync_skcipher_clear_flags(op->fallback_tfm, CRYPTO_TFM_REQ_MASK);
 	crypto_sync_skcipher_set_flags(op->fallback_tfm, tfm->base.crt_flags & CRYPTO_TFM_REQ_MASK);
@@ -416,14 +410,11 @@ int sun8i_ce_des3_setkey(struct crypto_skcipher *tfm, const u8 *key,
 	if (err)
 		return err;
 
-	if (op->key) {
-		memzero_explicit(op->key, op->keylen);
-		kfree(op->key);
-	}
-	op->keylen = keylen;
+	kfree_sensitive(op->key);
 	op->key = kmemdup(key, keylen, GFP_KERNEL | GFP_DMA);
 	if (!op->key)
 		return -ENOMEM;
+	op->keylen = keylen;
 
 	crypto_sync_skcipher_clear_flags(op->fallback_tfm, CRYPTO_TFM_REQ_MASK);
 	crypto_sync_skcipher_set_flags(op->fallback_tfm, tfm->base.crt_flags & CRYPTO_TFM_REQ_MASK);
diff --git a/drivers/crypto/allwinner/sun8i-ss/sun8i-ss-cipher.c b/drivers/crypto/allwinner/sun8i-ss/sun8i-ss-cipher.c
index 5246ef4f5430..0495fbc27fcc 100644
--- a/drivers/crypto/allwinner/sun8i-ss/sun8i-ss-cipher.c
+++ b/drivers/crypto/allwinner/sun8i-ss/sun8i-ss-cipher.c
@@ -249,7 +249,6 @@ static int sun8i_ss_cipher(struct skcipher_request *areq)
 			offset = areq->cryptlen - ivsize;
 			if (rctx->op_dir & SS_DECRYPTION) {
 				memcpy(areq->iv, backup_iv, ivsize);
-				memzero_explicit(backup_iv, ivsize);
 				kfree_sensitive(backup_iv);
 			} else {
 				scatterwalk_map_and_copy(areq->iv, areq->dst, offset,
@@ -367,10 +366,7 @@ void sun8i_ss_cipher_exit(struct crypto_tfm *tfm)
 {
 	struct sun8i_cipher_tfm_ctx *op = crypto_tfm_ctx(tfm);
 
-	if (op->key) {
-		memzero_explicit(op->key, op->keylen);
-		kfree(op->key);
-	}
+	kfree_sensitive(op->key);
 	crypto_free_sync_skcipher(op->fallback_tfm);
 	pm_runtime_put_sync(op->ss->dev);
 }
@@ -392,14 +388,11 @@ int sun8i_ss_aes_setkey(struct crypto_skcipher *tfm, const u8 *key,
 		dev_dbg(ss->dev, "ERROR: Invalid keylen %u\n", keylen);
 		return -EINVAL;
 	}
-	if (op->key) {
-		memzero_explicit(op->key, op->keylen);
-		kfree(op->key);
-	}
-	op->keylen = keylen;
+	kfree_sensitive(op->key);
 	op->key = kmemdup(key, keylen, GFP_KERNEL | GFP_DMA);
 	if (!op->key)
 		return -ENOMEM;
+	op->keylen = keylen;
 
 	crypto_sync_skcipher_clear_flags(op->fallback_tfm, CRYPTO_TFM_REQ_MASK);
 	crypto_sync_skcipher_set_flags(op->fallback_tfm, tfm->base.crt_flags & CRYPTO_TFM_REQ_MASK);
@@ -418,14 +411,11 @@ int sun8i_ss_des3_setkey(struct crypto_skcipher *tfm, const u8 *key,
 		return -EINVAL;
 	}
 
-	if (op->key) {
-		memzero_explicit(op->key, op->keylen);
-		kfree(op->key);
-	}
-	op->keylen = keylen;
+	kfree_sensitive(op->key);
 	op->key = kmemdup(key, keylen, GFP_KERNEL | GFP_DMA);
 	if (!op->key)
 		return -ENOMEM;
+	op->keylen = keylen;
 
 	crypto_sync_skcipher_clear_flags(op->fallback_tfm, CRYPTO_TFM_REQ_MASK);
 	crypto_sync_skcipher_set_flags(op->fallback_tfm, tfm->base.crt_flags & CRYPTO_TFM_REQ_MASK);
diff --git a/drivers/crypto/amlogic/amlogic-gxl-cipher.c b/drivers/crypto/amlogic/amlogic-gxl-cipher.c
index fd1269900d67..6aa9ce7bbbd4 100644
--- a/drivers/crypto/amlogic/amlogic-gxl-cipher.c
+++ b/drivers/crypto/amlogic/amlogic-gxl-cipher.c
@@ -341,10 +341,7 @@ void meson_cipher_exit(struct crypto_tfm *tfm)
 {
 	struct meson_cipher_tfm_ctx *op = crypto_tfm_ctx(tfm);
 
-	if (op->key) {
-		memzero_explicit(op->key, op->keylen);
-		kfree(op->key);
-	}
+	kfree_sensitive(op->key);
 	crypto_free_sync_skcipher(op->fallback_tfm);
 }
 
@@ -368,14 +365,11 @@ int meson_aes_setkey(struct crypto_skcipher *tfm, const u8 *key,
 		dev_dbg(mc->dev, "ERROR: Invalid keylen %u\n", keylen);
 		return -EINVAL;
 	}
-	if (op->key) {
-		memzero_explicit(op->key, op->keylen);
-		kfree(op->key);
-	}
-	op->keylen = keylen;
+	kfree_sensitive(op->key);
 	op->key = kmemdup(key, keylen, GFP_KERNEL | GFP_DMA);
 	if (!op->key)
 		return -ENOMEM;
+	op->keylen = keylen;
 
 	return crypto_sync_skcipher_setkey(op->fallback_tfm, key, keylen);
 }
diff --git a/drivers/crypto/inside-secure/safexcel_hash.c b/drivers/crypto/inside-secure/safexcel_hash.c
index 43962bc709c6..4a2d162914de 100644
--- a/drivers/crypto/inside-secure/safexcel_hash.c
+++ b/drivers/crypto/inside-secure/safexcel_hash.c
@@ -1081,8 +1081,7 @@ static int safexcel_hmac_init_pad(struct ahash_request *areq,
 		}
 
 		/* Avoid leaking */
-		memzero_explicit(keydup, keylen);
-		kfree(keydup);
+		kfree_sensitive(keydup);
 
 		if (ret)
 			return ret;
-- 
2.18.1