[PATCH v2 15/19] crypto: sun8i-ss: do not fallback if cryptlen is less than sg length

[Corentin Labbe <clabbe@xxxxxxxxxxxx>]

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@xxxxxxxxxxxx>
---
 .../allwinner/sun8i-ss/sun8i-ss-cipher.c      | 19 +++++++++----------
 1 file changed, 9 insertions(+), 10 deletions(-)

diff --git a/drivers/crypto/allwinner/sun8i-ss/sun8i-ss-cipher.c b/drivers/crypto/allwinner/sun8i-ss/sun8i-ss-cipher.c
index 7f1940c6cc41..5bb950182026 100644
--- a/drivers/crypto/allwinner/sun8i-ss/sun8i-ss-cipher.c
+++ b/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);
 	}
 
-- 
2.35.1