crypto: sun8i-ss - do not fallback if cryptlen is less than sg length

The sg length could be more than remaining data on it.
So check the length requirement against the minimum between those two
values.
Signed-off-by: Corentin Labbe <clabbe@baylibre.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

drivers/crypto/allwinner/sun8i-ss/sun8i-ss-cipher.c

@@ -28,6 +28,7 @@ static bool sun8i_ss_need_fallback(struct skcipher_request *areq)
 	struct scatterlist *in_sg = areq->src;
 	struct scatterlist *out_sg = areq->dst;
 	struct scatterlist *sg;
+	unsigned int todo, len;
 
 	if (areq->cryptlen == 0 || areq->cryptlen % 16) {
 		algt->stat_fb_len++;
@@ -40,13 +41,11 @@ static bool sun8i_ss_need_fallback(struct skcipher_request *areq)
 		return true;
 	}
 
+	len = areq->cryptlen;
 	sg = areq->src;
 	while (sg) {
-		if ((sg->length % 16) != 0) {
-			algt->stat_fb_sglen++;
-			return true;
-		}
-		if ((sg_dma_len(sg) % 16) != 0) {
+		todo = min(len, sg->length);
+		if ((todo % 16) != 0) {
 			algt->stat_fb_sglen++;
 			return true;
 		}
@@ -54,15 +53,14 @@ static bool sun8i_ss_need_fallback(struct skcipher_request *areq)
 			algt->stat_fb_align++;
 			return true;
 		}
+		len -= todo;
 		sg = sg_next(sg);
 	}
+	len = areq->cryptlen;
 	sg = areq->dst;
 	while (sg) {
-		if ((sg->length % 16) != 0) {
-			algt->stat_fb_sglen++;
-			return true;
-		}
-		if ((sg_dma_len(sg) % 16) != 0) {
+		todo = min(len, sg->length);
+		if ((todo % 16) != 0) {
 			algt->stat_fb_sglen++;
 			return true;
 		}
@@ -70,6 +68,7 @@ static bool sun8i_ss_need_fallback(struct skcipher_request *areq)
 			algt->stat_fb_align++;
 			return true;
 		}
+		len -= todo;
 		sg = sg_next(sg);
 	}