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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org,
        =?UTF-8?q?Horia=20Geant=C4=83?= <horia.geanta@nxp.com>,
        Herbert Xu <herbert@gondor.apana.org.au>
Subject: [PATCH 4.18 161/168] crypto: caam/jr - fix ablkcipher_edesc pointer arithmetic
Date:   Mon,  8 Oct 2018 20:32:21 +0200
Message-Id: <20181008175626.173258169@linuxfoundation.org>
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4.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Horia Geantă <horia.geanta@nxp.com>

commit 13cc6f48c7434ce46ba6dbc90003a136a263d75a upstream.

In some cases the zero-length hw_desc array at the end of
ablkcipher_edesc struct requires for 4B of tail padding.

Due to tail padding and the way pointers to S/G table and IV
are computed:
	edesc->sec4_sg = (void *)edesc + sizeof(struct ablkcipher_edesc) +
			 desc_bytes;
	iv = (u8 *)edesc->hw_desc + desc_bytes + sec4_sg_bytes;
first 4 bytes of IV are overwritten by S/G table.

Update computation of pointer to S/G table to rely on offset of hw_desc
member and not on sizeof() operator.

Cc: <stable@vger.kernel.org> # 4.13+
Fixes: 115957bb3e59 ("crypto: caam - fix IV DMA mapping and updating")
Signed-off-by: Horia Geantă <horia.geanta@nxp.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/crypto/caam/caamalg.c |    8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

--- a/drivers/crypto/caam/caamalg.c
+++ b/drivers/crypto/caam/caamalg.c
@@ -1553,8 +1553,8 @@ static struct ablkcipher_edesc *ablkciph
 	edesc->src_nents = src_nents;
 	edesc->dst_nents = dst_nents;
 	edesc->sec4_sg_bytes = sec4_sg_bytes;
-	edesc->sec4_sg = (void *)edesc + sizeof(struct ablkcipher_edesc) +
-			 desc_bytes;
+	edesc->sec4_sg = (struct sec4_sg_entry *)((u8 *)edesc->hw_desc +
+						  desc_bytes);
 	edesc->iv_dir = DMA_TO_DEVICE;
 
 	/* Make sure IV is located in a DMAable area */
@@ -1757,8 +1757,8 @@ static struct ablkcipher_edesc *ablkciph
 	edesc->src_nents = src_nents;
 	edesc->dst_nents = dst_nents;
 	edesc->sec4_sg_bytes = sec4_sg_bytes;
-	edesc->sec4_sg = (void *)edesc + sizeof(struct ablkcipher_edesc) +
-			 desc_bytes;
+	edesc->sec4_sg = (struct sec4_sg_entry *)((u8 *)edesc->hw_desc +
+						  desc_bytes);
 	edesc->iv_dir = DMA_FROM_DEVICE;
 
 	/* Make sure IV is located in a DMAable area */