linux-kernel - [PATCH 3.16 122/305] crypto: ccp - Fix AES XTS error for request sizes above 4096

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Message-ID: <lsq.1471110171.932760535@decadent.org.uk>
Date:	Sat, 13 Aug 2016 18:42:51 +0100
From:	Ben Hutchings <ben@...adent.org.uk>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:	akpm@...ux-foundation.org,
	"Tom Lendacky" <thomas.lendacky@....com>,
	"Herbert Xu" <herbert@...dor.apana.org.au>
Subject: [PATCH 3.16 122/305] crypto: ccp - Fix AES XTS error for request
 sizes above 4096

3.16.37-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Tom Lendacky <thomas.lendacky@....com>

commit ab6a11a7c8ef47f996974dd3c648c2c0b1a36ab1 upstream.

The ccp-crypto module for AES XTS support has a bug that can allow requests
greater than 4096 bytes in size to be passed to the CCP hardware. The CCP
hardware does not support request sizes larger than 4096, resulting in
incorrect output. The request should actually be handled by the fallback
mechanism instantiated by the ccp-crypto module.

Add a check to insure the request size is less than or equal to the maximum
supported size and use the fallback mechanism if it is not.

Signed-off-by: Tom Lendacky <thomas.lendacky@....com>
Signed-off-by: Herbert Xu <herbert@...dor.apana.org.au>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 drivers/crypto/ccp/ccp-crypto-aes-xts.c | 17 ++++++++++++-----
 1 file changed, 12 insertions(+), 5 deletions(-)

--- a/drivers/crypto/ccp/ccp-crypto-aes-xts.c
+++ b/drivers/crypto/ccp/ccp-crypto-aes-xts.c
@@ -123,6 +123,7 @@ static int ccp_aes_xts_crypt(struct ablk
 	struct ccp_ctx *ctx = crypto_tfm_ctx(req->base.tfm);
 	struct ccp_aes_req_ctx *rctx = ablkcipher_request_ctx(req);
 	unsigned int unit;
+	u32 unit_size;
 	int ret;
 
 	if (!ctx->u.aes.key_len)
@@ -134,11 +135,17 @@ static int ccp_aes_xts_crypt(struct ablk
 	if (!req->info)
 		return -EINVAL;
 
-	for (unit = 0; unit < ARRAY_SIZE(unit_size_map); unit++)
-		if (!(req->nbytes & (unit_size_map[unit].size - 1)))
-			break;
+	unit_size = CCP_XTS_AES_UNIT_SIZE__LAST;
+	if (req->nbytes <= unit_size_map[0].size) {
+		for (unit = 0; unit < ARRAY_SIZE(unit_size_map); unit++) {
+			if (!(req->nbytes & (unit_size_map[unit].size - 1))) {
+				unit_size = unit_size_map[unit].value;
+				break;
+			}
+		}
+	}
 
-	if ((unit_size_map[unit].value == CCP_XTS_AES_UNIT_SIZE__LAST) ||
+	if ((unit_size == CCP_XTS_AES_UNIT_SIZE__LAST) ||
 	    (ctx->u.aes.key_len != AES_KEYSIZE_128)) {
 		/* Use the fallback to process the request for any
 		 * unsupported unit sizes or key sizes
@@ -159,7 +166,7 @@ static int ccp_aes_xts_crypt(struct ablk
 	rctx->cmd.engine = CCP_ENGINE_XTS_AES_128;
 	rctx->cmd.u.xts.action = (encrypt) ? CCP_AES_ACTION_ENCRYPT
 					   : CCP_AES_ACTION_DECRYPT;
-	rctx->cmd.u.xts.unit_size = unit_size_map[unit].value;
+	rctx->cmd.u.xts.unit_size = unit_size;
 	rctx->cmd.u.xts.key = &ctx->u.aes.key_sg;
 	rctx->cmd.u.xts.key_len = ctx->u.aes.key_len;
 	rctx->cmd.u.xts.iv = &rctx->iv_sg;