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From:   Waiman Long <longman@redhat.com>
To:     Andrew Morton <akpm@linux-foundation.org>,
        David Howells <dhowells@redhat.com>,
        Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>,
        James Morris <jmorris@namei.org>,
        "Serge E. Hallyn" <serge@hallyn.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Joe Perches <joe@perches.com>,
        Matthew Wilcox <willy@infradead.org>,
        David Rientjes <rientjes@google.com>,
        Corentin Labbe <clabbe.montjoie@gmail.com>,
        Herbert Xu <herbert@gondor.apana.org.au>,
        "David S. Miller" <davem@davemloft.net>,
        Chen-Yu Tsai <wens@csie.org>
Cc:     linux-mm@kvack.org, keyrings@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-crypto@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org,
        linux-amlogic@lists.infradead.org, Waiman Long <longman@redhat.com>
Subject: [PATCH v3 2/3] crypto: Remove unnecessary memzero_explicit()
Date:   Tue, 14 Apr 2020 16:02:14 -0400
Message-Id: <20200414200214.1873-1-longman@redhat.com>
In-Reply-To: <20200413211550.8307-1-longman@redhat.com>
References: <20200413211550.8307-1-longman@redhat.com>
Sender: linux-crypto-owner@vger.kernel.org
Precedence: bulk

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,
keylen is cleared if key memory allocation fails.

Signed-off-by: Waiman Long <longman@redhat.com>
---
 .../allwinner/sun8i-ce/sun8i-ce-cipher.c      | 23 +++++++-----------
 .../allwinner/sun8i-ss/sun8i-ss-cipher.c      | 24 +++++++------------
 drivers/crypto/amlogic/amlogic-gxl-cipher.c   | 14 ++++-------
 drivers/crypto/inside-secure/safexcel_hash.c  |  3 +--
 4 files changed, 24 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..a2bac10d2876 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 +388,13 @@ 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);
-	}
+	kfree_sensitive(op->key);
 	op->keylen = keylen;
 	op->key = kmemdup(key, keylen, GFP_KERNEL | GFP_DMA);
-	if (!op->key)
+	if (unlikely(!op->key)) {
+		op->keylen = 0;
 		return -ENOMEM;
+	}
 
 	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 +412,13 @@ 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);
-	}
+	kfree_sensitive(op->key);
 	op->keylen = keylen;
 	op->key = kmemdup(key, keylen, GFP_KERNEL | GFP_DMA);
-	if (!op->key)
+	if (unlikely(!op->key)) {
+		op->keylen = 0;
 		return -ENOMEM;
+	}
 
 	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..a24d567a6c36 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 +388,13 @@ 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);
-	}
+	kfree_sensitive(op->key);
 	op->keylen = keylen;
 	op->key = kmemdup(key, keylen, GFP_KERNEL | GFP_DMA);
-	if (!op->key)
+	if (unlikely(!op->key))
+		op->keylen = 0;
 		return -ENOMEM;
+	}
 
 	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 +413,13 @@ 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);
-	}
+	kfree_sensitive(op->key);
 	op->keylen = keylen;
 	op->key = kmemdup(key, keylen, GFP_KERNEL | GFP_DMA);
-	if (!op->key)
+	if (unlikely(!op->key))
+		op->keylen = 0;
 		return -ENOMEM;
+	}
 
 	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..5312bad7534e 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 +365,13 @@ 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);
-	}
+	kfree_sensitive(op->key);
 	op->keylen = keylen;
 	op->key = kmemdup(key, keylen, GFP_KERNEL | GFP_DMA);
-	if (!op->key)
+	if (unlikely(!op->key))
+		op->keylen = 0;
 		return -ENOMEM;
+	}
 
 	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