[PATCH 11/16] crypto: atmel-aes - Fix counter overflow in CTR mode

[Tudor.Ambarus]

From: Tudor Ambarus <tudor.ambarus@xxxxxxxxxxxxx>

32 bit counter is not supported by neither of our AES IPs, all implement
a 16 bit block counter. Drop the 32 bit block counter logic.

Fixes: fcac83656a3e ("crypto: atmel-aes - fix the counter overflow in CTR mode")
Signed-off-by: Tudor Ambarus <tudor.ambarus@xxxxxxxxxxxxx>
---
 drivers/crypto/atmel-aes.c | 37 ++++++++++++-------------------------
 1 file changed, 12 insertions(+), 25 deletions(-)

diff --git a/drivers/crypto/atmel-aes.c b/drivers/crypto/atmel-aes.c
index d7e28ec456ff..cbfe6ccd2a0d 100644
--- a/drivers/crypto/atmel-aes.c
+++ b/drivers/crypto/atmel-aes.c
@@ -89,7 +89,6 @@
 struct atmel_aes_caps {
 	bool			has_dualbuff;
 	bool			has_cfb64;
-	bool			has_ctr32;
 	bool			has_gcm;
 	bool			has_xts;
 	bool			has_authenc;
@@ -1019,8 +1018,9 @@ static int atmel_aes_ctr_transfer(struct atmel_aes_dev *dd)
 	struct atmel_aes_ctr_ctx *ctx = atmel_aes_ctr_ctx_cast(dd->ctx);
 	struct skcipher_request *req = skcipher_request_cast(dd->areq);
 	struct scatterlist *src, *dst;
-	u32 ctr, blocks;
 	size_t datalen;
+	u32 ctr;
+	u16 blocks, start, end;
 	bool use_dma, fragmented = false;
 
 	/* Check for transfer completion. */
@@ -1032,27 +1032,17 @@ static int atmel_aes_ctr_transfer(struct atmel_aes_dev *dd)
 	datalen = req->cryptlen - ctx->offset;
 	blocks = DIV_ROUND_UP(datalen, AES_BLOCK_SIZE);
 	ctr = be32_to_cpu(ctx->iv[3]);
-	if (dd->caps.has_ctr32) {
-		/* Check 32bit counter overflow. */
-		u32 start = ctr;
-		u32 end = start + blocks - 1;
-
-		if (end < start) {
-			ctr |= 0xffffffff;
-			datalen = AES_BLOCK_SIZE * -start;
-			fragmented = true;
-		}
-	} else {
-		/* Check 16bit counter overflow. */
-		u16 start = ctr & 0xffff;
-		u16 end = start + (u16)blocks - 1;
-
-		if (blocks >> 16 || end < start) {
-			ctr |= 0xffff;
-			datalen = AES_BLOCK_SIZE * (0x10000-start);
-			fragmented = true;
-		}
+
+	/* Check 16bit counter overflow. */
+	start = ctr & 0xffff;
+	end = start + blocks - 1;
+
+	if (blocks >> 16 || end < start) {
+		ctr |= 0xffff;
+		datalen = AES_BLOCK_SIZE * (0x10000 - start);
+		fragmented = true;
 	}
+
 	use_dma = (datalen >= ATMEL_AES_DMA_THRESHOLD);
 
 	/* Jump to offset. */
@@ -2538,7 +2528,6 @@ static void atmel_aes_get_cap(struct atmel_aes_dev *dd)
 {
 	dd->caps.has_dualbuff = 0;
 	dd->caps.has_cfb64 = 0;
-	dd->caps.has_ctr32 = 0;
 	dd->caps.has_gcm = 0;
 	dd->caps.has_xts = 0;
 	dd->caps.has_authenc = 0;
@@ -2549,7 +2538,6 @@ static void atmel_aes_get_cap(struct atmel_aes_dev *dd)
 	case 0x500:
 		dd->caps.has_dualbuff = 1;
 		dd->caps.has_cfb64 = 1;
-		dd->caps.has_ctr32 = 1;
 		dd->caps.has_gcm = 1;
 		dd->caps.has_xts = 1;
 		dd->caps.has_authenc = 1;
@@ -2558,7 +2546,6 @@ static void atmel_aes_get_cap(struct atmel_aes_dev *dd)
 	case 0x200:
 		dd->caps.has_dualbuff = 1;
 		dd->caps.has_cfb64 = 1;
-		dd->caps.has_ctr32 = 1;
 		dd->caps.has_gcm = 1;
 		dd->caps.max_burst_size = 4;
 		break;
-- 
2.14.5