linux-kernel - [PATCH 29/35] crypto: ccree: don't map MAC key on stack

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Date:   Thu, 18 Apr 2019 16:39:04 +0300
From:   Gilad Ben-Yossef <gilad@...yossef.com>
To:     Herbert Xu <herbert@...dor.apana.org.au>,
        "David S. Miller" <davem@...emloft.net>
Cc:     Ofir Drang <ofir.drang@....com>, stable@...r.kernel.org,
        linux-crypto@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH 29/35] crypto: ccree: don't map MAC key on stack

The MAC hash key might be passed to us on stack. Copy it to
a slab buffer before mapping to gurantee proper DMA mapping.

Signed-off-by: Gilad Ben-Yossef <gilad@...yossef.com>
Cc: stable@...r.kernel.org # v4.19+
---
 drivers/crypto/ccree/cc_hash.c | 24 +++++++++++++++++++++---
 1 file changed, 21 insertions(+), 3 deletions(-)

diff --git a/drivers/crypto/ccree/cc_hash.c b/drivers/crypto/ccree/cc_hash.c
index 36e9fb4141f8..a6abe4e3bb0e 100644
--- a/drivers/crypto/ccree/cc_hash.c
+++ b/drivers/crypto/ccree/cc_hash.c
@@ -69,6 +69,7 @@ struct cc_hash_alg {
 struct hash_key_req_ctx {
 	u32 keylen;
 	dma_addr_t key_dma_addr;
+	u8 *key;
 };
 
 /* hash per-session context */
@@ -742,13 +743,20 @@ static int cc_hash_setkey(struct crypto_ahash *ahash, const u8 *key,
 	ctx->key_params.keylen = keylen;
 	ctx->key_params.key_dma_addr = 0;
 	ctx->is_hmac = true;
+	ctx->key_params.key = NULL;
 
 	if (keylen) {
+		ctx->key_params.key = kmemdup(key, keylen, GFP_KERNEL);
+		if (!ctx->key_params.key)
+			return -ENOMEM;
+
 		ctx->key_params.key_dma_addr =
-			dma_map_single(dev, (void *)key, keylen, DMA_TO_DEVICE);
+			dma_map_single(dev, (void *)ctx->key_params.key, keylen,
+				       DMA_TO_DEVICE);
 		if (dma_mapping_error(dev, ctx->key_params.key_dma_addr)) {
 			dev_err(dev, "Mapping key va=0x%p len=%u for DMA failed\n",
-				key, keylen);
+				ctx->key_params.key, keylen);
+			kzfree(ctx->key_params.key);
 			return -ENOMEM;
 		}
 		dev_dbg(dev, "mapping key-buffer: key_dma_addr=%pad keylen=%u\n",
@@ -899,6 +907,9 @@ static int cc_hash_setkey(struct crypto_ahash *ahash, const u8 *key,
 		dev_dbg(dev, "Unmapped key-buffer: key_dma_addr=%pad keylen=%u\n",
 			&ctx->key_params.key_dma_addr, ctx->key_params.keylen);
 	}
+
+	kzfree(ctx->key_params.key);
+
 	return rc;
 }
 
@@ -925,11 +936,16 @@ static int cc_xcbc_setkey(struct crypto_ahash *ahash,
 
 	ctx->key_params.keylen = keylen;
 
+	ctx->key_params.key = kmemdup(key, keylen, GFP_KERNEL);
+	if (!ctx->key_params.key)
+		return -ENOMEM;
+
 	ctx->key_params.key_dma_addr =
-		dma_map_single(dev, (void *)key, keylen, DMA_TO_DEVICE);
+		dma_map_single(dev, ctx->key_params.key, keylen, DMA_TO_DEVICE);
 	if (dma_mapping_error(dev, ctx->key_params.key_dma_addr)) {
 		dev_err(dev, "Mapping key va=0x%p len=%u for DMA failed\n",
 			key, keylen);
+		kzfree(ctx->key_params.key);
 		return -ENOMEM;
 	}
 	dev_dbg(dev, "mapping key-buffer: key_dma_addr=%pad keylen=%u\n",
@@ -981,6 +997,8 @@ static int cc_xcbc_setkey(struct crypto_ahash *ahash,
 	dev_dbg(dev, "Unmapped key-buffer: key_dma_addr=%pad keylen=%u\n",
 		&ctx->key_params.key_dma_addr, ctx->key_params.keylen);
 
+	kzfree(ctx->key_params.key);
+
 	return rc;
 }
 
-- 
2.21.0