crypto: mxs-dcp - fix scatterlist linearization for hash

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>

drivers/crypto/mxs-dcp.c

@@ -20,6 +20,7 @@
 #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
@@ -611,35 +612,33 @@ 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);
+	src = req->src;
+	len = req->nbytes;
 
-		do {
+	while (len) {
 		if (actx->fill + len > DCP_BUF_SZ)
 			clen = DCP_BUF_SZ - actx->fill;
 		else
 			clen = len;
 
-			memcpy(in_buf + actx->fill, src_buf, clen);
+		scatterwalk_map_and_copy(in_buf + actx->fill, src, oft, clen,
+					 0);
+
 		len -= clen;
-			src_buf += clen;
+		oft += clen;
 		actx->fill += clen;
 
 		/*
@@ -653,7 +652,6 @@ static int dcp_sha_req_to_buf(struct crypto_async_request *arq)
 			actx->fill = 0;
 			rctx->init = 0;
 		}
-		} while (len);
 	}
 
 	if (fin) {