[PATCH 4/7] crypto: sahara - fix processing requests with cryptlen < sg->length

[ovidiu.panait@xxxxxxxxxxxxx]

From: Ovidiu Panait <ovidiu.panait@xxxxxxxxxxxxx>

It's not always the case that the entire sg entry needs to be processed.
Currently, when cryptlen is less than sg->legth, "Descriptor length" errors
are encountered.

The error was noticed when testing xts(sahara-ecb-aes) with arbitrary sized
input data. To fix this, take the actual request size into account when
populating the hw links.

Fixes: 5de8875281e1 ("crypto: sahara - Add driver for SAHARA2 accelerator.")
Signed-off-by: Ovidiu Panait <ovidiu.panait@xxxxxxxxxxxxx>
---
 drivers/crypto/sahara.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/crypto/sahara.c b/drivers/crypto/sahara.c
index 863171b44cda..cbb7153e4162 100644
--- a/drivers/crypto/sahara.c
+++ b/drivers/crypto/sahara.c
@@ -444,6 +444,7 @@ static int sahara_hw_descriptor_create(struct sahara_dev *dev)
 	int ret;
 	int i, j;
 	int idx = 0;
+	u32 len;
 
 	memcpy(dev->key_base, ctx->key, ctx->keylen);
 
@@ -494,12 +495,14 @@ static int sahara_hw_descriptor_create(struct sahara_dev *dev)
 	/* Create input links */
 	dev->hw_desc[idx]->p1 = dev->hw_phys_link[0];
 	sg = dev->in_sg;
+	len = dev->total;
 	for (i = 0; i < dev->nb_in_sg; i++) {
-		dev->hw_link[i]->len = sg->length;
+		dev->hw_link[i]->len = min(len, sg->length);
 		dev->hw_link[i]->p = sg->dma_address;
 		if (i == (dev->nb_in_sg - 1)) {
 			dev->hw_link[i]->next = 0;
 		} else {
+			len -= min(len, sg->length);
 			dev->hw_link[i]->next = dev->hw_phys_link[i + 1];
 			sg = sg_next(sg);
 		}
@@ -508,12 +511,14 @@ static int sahara_hw_descriptor_create(struct sahara_dev *dev)
 	/* Create output links */
 	dev->hw_desc[idx]->p2 = dev->hw_phys_link[i];
 	sg = dev->out_sg;
+	len = dev->total;
 	for (j = i; j < dev->nb_out_sg + i; j++) {
-		dev->hw_link[j]->len = sg->length;
+		dev->hw_link[j]->len = min(len, sg->length);
 		dev->hw_link[j]->p = sg->dma_address;
 		if (j == (dev->nb_out_sg + i - 1)) {
 			dev->hw_link[j]->next = 0;
 		} else {
+			len -= min(len, sg->length);
 			dev->hw_link[j]->next = dev->hw_phys_link[j + 1];
 			sg = sg_next(sg);
 		}
-- 
2.34.1