[PATCH 19/19] crypto: sun8i-ce: do not fallback if cryptlen is less than sg length

[Corentin Labbe]

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 at baylibre.com>
---
 drivers/crypto/allwinner/sun8i-ce/sun8i-ce-cipher.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/drivers/crypto/allwinner/sun8i-ce/sun8i-ce-cipher.c b/drivers/crypto/allwinner/sun8i-ce/sun8i-ce-cipher.c
index 315a62e424d6..74b4e910a38d 100644
--- a/drivers/crypto/allwinner/sun8i-ce/sun8i-ce-cipher.c
+++ b/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;
-- 
2.34.1