crypto: mxs-dcp - fix scatterlist linearization for hash

commit fa03481b upstream.

The incorrect traversal of the scatterlist, during the linearization phase
lead to computing the hash value of the wrong input buffer.
New implementation uses scatterwalk_map_and_copy()
to address this issue.

Cc: <stable@vger.kernel.org>
Fixes: 15b59e7c ("crypto: mxs - Add Freescale MXS DCP driver")
Signed-off-by: Rosioru Dragos <dragos.rosioru@nxp.com>
Reviewed-by: Horia Geantă <horia.geanta@nxp.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/crypto/mxs-dcp.c

@@ -25,6 +25,7 @@
 #include <crypto/sha.h>
 #include <crypto/internal/hash.h>
 #include <crypto/internal/skcipher.h>
+#include <crypto/scatterwalk.h>
 
 #define DCP_MAX_CHANS	4
 #define DCP_BUF_SZ	PAGE_SIZE
@@ -621,49 +622,46 @@ static int dcp_sha_req_to_buf(struct crypto_async_request *arq)
 	struct dcp_async_ctx *actx = crypto_ahash_ctx(tfm);
 	struct dcp_sha_req_ctx *rctx = ahash_request_ctx(req);
 	struct hash_alg_common *halg = crypto_hash_alg_common(tfm);
-	const int nents = sg_nents(req->src);
 
 	uint8_t *in_buf = sdcp->coh->sha_in_buf;
 	uint8_t *out_buf = sdcp->coh->sha_out_buf;
 
-	uint8_t *src_buf;
-
 	struct scatterlist *src;
 
-	unsigned int i, len, clen;
+	unsigned int i, len, clen, oft = 0;
 	int ret;
 
 	int fin = rctx->fini;
 	if (fin)
 		rctx->fini = 0;
 
-	for_each_sg(req->src, src, nents, i) {
-		src_buf = sg_virt(src);
-		len = sg_dma_len(src);
-
-		do {
-			if (actx->fill + len > DCP_BUF_SZ)
-				clen = DCP_BUF_SZ - actx->fill;
-			else
-				clen = len;
-
-			memcpy(in_buf + actx->fill, src_buf, clen);
-			len -= clen;
-			src_buf += clen;
-			actx->fill += clen;
+	src = req->src;
+	len = req->nbytes;
 
-			/*
-			 * If we filled the buffer and still have some
-			 * more data, submit the buffer.
-			 */
-			if (len && actx->fill == DCP_BUF_SZ) {
-				ret = mxs_dcp_run_sha(req);
-				if (ret)
-					return ret;
-				actx->fill = 0;
-				rctx->init = 0;
-			}
-		} while (len);
+	while (len) {
+		if (actx->fill + len > DCP_BUF_SZ)
+			clen = DCP_BUF_SZ - actx->fill;
+		else
+			clen = len;
+
+		scatterwalk_map_and_copy(in_buf + actx->fill, src, oft, clen,
+					 0);
+
+		len -= clen;
+		oft += clen;
+		actx->fill += clen;
+
+		/*
+		 * If we filled the buffer and still have some
+		 * more data, submit the buffer.
+		 */
+		if (len && actx->fill == DCP_BUF_SZ) {
+			ret = mxs_dcp_run_sha(req);
+			if (ret)
+				return ret;
+			actx->fill = 0;
+			rctx->init = 0;
+		}
 	}
 
 	if (fin) {