crypto: sun8i-ce - 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-ce/sun8i-ce-cipher.c

@@ -27,6 +27,7 @@ static int sun8i_ce_cipher_need_fallback(struct skcipher_request *areq)
 	struct scatterlist *sg;
 	struct skcipher_alg *alg = crypto_skcipher_alg(tfm);
 	struct sun8i_ce_alg_template *algt;
+	unsigned int todo, len;
 
 	algt = container_of(alg, struct sun8i_ce_alg_template, alg.skcipher);
 
@@ -51,28 +52,35 @@ static int sun8i_ce_cipher_need_fallback(struct skcipher_request *areq)
 		return true;
 	}
 
+	len = areq->cryptlen;
 	sg = areq->src;
 	while (sg) {
 		if (!IS_ALIGNED(sg->offset, sizeof(u32))) {
 			algt->stat_fb_srcali++;
 			return true;
 		}
-		if (sg->length % 4) {
+		todo = min(len, sg->length);
+		if (todo % 4) {
 			algt->stat_fb_srclen++;
 			return true;
 		}
+		len -= todo;
 		sg = sg_next(sg);
 	}
+
+	len = areq->cryptlen;
 	sg = areq->dst;
 	while (sg) {
 		if (!IS_ALIGNED(sg->offset, sizeof(u32))) {
 			algt->stat_fb_dstali++;
 			return true;
 		}
-		if (sg->length % 4) {
+		todo = min(len, sg->length);
+		if (todo % 4) {
 			algt->stat_fb_dstlen++;
 			return true;
 		}
+		len -= todo;
 		sg = sg_next(sg);
 	}
 	return false;