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

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Date:   Mon,  2 May 2022 20:19:29 +0000
From:   Corentin Labbe <clabbe@...libre.com>
To:     herbert@...dor.apana.org.au, jernej.skrabec@...il.com,
        samuel@...lland.org, wens@...e.org
Cc:     linux-arm-kernel@...ts.infradead.org, linux-crypto@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-sunxi@...ts.linux.dev,
        Corentin Labbe <clabbe@...libre.com>
Subject: [PATCH v2 19/19] 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@...libre.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;
-- 
2.35.1