[PATCH 5.5 364/367] crypto: atmel-aes - Fix CTR counter overflow when multiple fragments

[Greg Kroah-Hartman]

From: Tudor Ambarus <tudor.ambarus@xxxxxxxxxxxxx>

[ Upstream commit 3907ccfaec5d9965e306729936fc732c94d2c1e7 ]

The CTR transfer works in fragments of data of maximum 1 MByte because
of the 16 bit CTR counter embedded in the IP. Fix the CTR counter
overflow handling for messages larger than 1 MByte.

Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
Fixes: 781a08d9740a ("crypto: atmel-aes - Fix counter overflow in CTR mode")
Signed-off-by: Tudor Ambarus <tudor.ambarus@xxxxxxxxxxxxx>
Signed-off-by: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 drivers/crypto/atmel-aes.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/crypto/atmel-aes.c b/drivers/crypto/atmel-aes.c
index ea9dcd7ce799b..b4dee726b2530 100644
--- a/drivers/crypto/atmel-aes.c
+++ b/drivers/crypto/atmel-aes.c
@@ -121,7 +121,7 @@ struct atmel_aes_ctr_ctx {
 	size_t			offset;
 	struct scatterlist	src[2];
 	struct scatterlist	dst[2];
-	u16			blocks;
+	u32			blocks;
 };
 
 struct atmel_aes_gcm_ctx {
@@ -528,6 +528,12 @@ static void atmel_aes_ctr_update_req_iv(struct atmel_aes_dev *dd)
 	unsigned int ivsize = crypto_skcipher_ivsize(skcipher);
 	int i;
 
+	/*
+	 * The CTR transfer works in fragments of data of maximum 1 MByte
+	 * because of the 16 bit CTR counter embedded in the IP. When reaching
+	 * here, ctx->blocks contains the number of blocks of the last fragment
+	 * processed, there is no need to explicit cast it to u16.
+	 */
 	for (i = 0; i < ctx->blocks; i++)
 		crypto_inc((u8 *)ctx->iv, AES_BLOCK_SIZE);
 
-- 
2.20.1