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From:   Vincent Whitchurch <vincent.whitchurch@axis.com>
To:     <herbert@gondor.apana.org.au>, <davem@davemloft.net>,
        <jesper.nilsson@axis.com>, <lars.persson@axis.com>
CC:     <kernel@axis.com>,
        Vincent Whitchurch <vincent.whitchurch@axis.com>,
        <linux-crypto@vger.kernel.org>, <linux-kernel@vger.kernel.org>
Subject: [PATCH 04/12] crypto: axis - fix in-place CBC output IV
Date:   Tue, 10 Jan 2023 14:50:34 +0100
Message-ID: <20230110135042.2940847-5-vincent.whitchurch@axis.com>
In-Reply-To: <20230110135042.2940847-1-vincent.whitchurch@axis.com>
References: <20230110135042.2940847-1-vincent.whitchurch@axis.com>
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When CBC is done in-place, the ->src is overwritten by the time the
operation is done, so the output IV must be based on a backup of the
ciphertext.

Signed-off-by: Vincent Whitchurch <vincent.whitchurch@axis.com>
---
 drivers/crypto/axis/artpec6_crypto.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/drivers/crypto/axis/artpec6_crypto.c b/drivers/crypto/axis/artpec6_crypto.c
index 67f510c497f2..87f82c314e48 100644
--- a/drivers/crypto/axis/artpec6_crypto.c
+++ b/drivers/crypto/axis/artpec6_crypto.c
@@ -321,6 +321,7 @@ struct artpec6_crypto_request_context {
 	u32 cipher_md;
 	bool decrypt;
 	struct artpec6_crypto_req_common common;
+	unsigned char last_ciphertext[AES_BLOCK_SIZE];
 	unsigned char iv_bounce[AES_BLOCK_SIZE] CRYPTO_MINALIGN_ATTR;
 };
 
@@ -1158,6 +1159,10 @@ static int artpec6_crypto_decrypt(struct skcipher_request *req)
 
 	switch (ctx->crypto_type) {
 	case ARTPEC6_CRYPTO_CIPHER_AES_CBC:
+		scatterwalk_map_and_copy(req_ctx->last_ciphertext, req->src,
+					 req->cryptlen - sizeof(req_ctx->last_ciphertext),
+					 sizeof(req_ctx->last_ciphertext), 0);
+
 		complete = artpec6_crypto_complete_cbc_decrypt;
 		break;
 	case ARTPEC6_CRYPTO_CIPHER_AES_CTR:
@@ -2185,10 +2190,10 @@ artpec6_crypto_complete_cbc_decrypt(struct crypto_async_request *req)
 {
 	struct skcipher_request *cipher_req = container_of(req,
 		struct skcipher_request, base);
+	struct artpec6_crypto_request_context *req_ctx = skcipher_request_ctx(cipher_req);
+
+	memcpy(cipher_req->iv, req_ctx->last_ciphertext, sizeof(req_ctx->last_ciphertext));
 
-	scatterwalk_map_and_copy(cipher_req->iv, cipher_req->src,
-				 cipher_req->cryptlen - AES_BLOCK_SIZE,
-				 AES_BLOCK_SIZE, 0);
 	req->complete(req, 0);
 }
 
-- 
2.34.1