crypto: sahara - fix processing hash requests with req->nbytes < sg->length

It's not always the case that the entire sg entry needs to be processed.
Currently, when nbytes is less than sg->length, "Descriptor length" errors
are encountered.

To fix this, take the actual request size into account when populating the
hw links.

Fixes: 5a2bb93f ("crypto: sahara - add support for SHA1/256")
Signed-off-by: Ovidiu Panait <ovidiu.panait@windriver.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

drivers/crypto/sahara.c

@@ -774,6 +774,7 @@ static int sahara_sha_hw_links_create(struct sahara_dev *dev,
 				       int start)
 {
 	struct scatterlist *sg;
+	unsigned int len;
 	unsigned int i;
 	int ret;
 
@@ -795,12 +796,14 @@ static int sahara_sha_hw_links_create(struct sahara_dev *dev,
 	if (!ret)
 		return -EFAULT;
 
+	len = rctx->total;
 	for (i = start; i < dev->nb_in_sg + start; i++) {
-		dev->hw_link[i]->len = sg->length;
+		dev->hw_link[i]->len = min(len, sg->length);
 		dev->hw_link[i]->p = sg->dma_address;
 		if (i == (dev->nb_in_sg + start - 1)) {
 			dev->hw_link[i]->next = 0;
 		} else {
+			len -= min(len, sg->length);
 			dev->hw_link[i]->next = dev->hw_phys_link[i + 1];
 			sg = sg_next(sg);
 		}