linux-kernel - [PATCH 5.6 100/161] crypto: virtio: Fix src/dst scatterlist calculation in __virtio_crypto_skcipher_do

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Date:   Tue, 16 Jun 2020 17:34:50 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, LABBE Corentin <clabbe@...libre.com>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        "Michael S. Tsirkin" <mst@...hat.com>,
        Jason Wang <jasowang@...hat.com>,
        "David S. Miller" <davem@...emloft.net>,
        virtualization@...ts.linux-foundation.org,
        Gonglei <arei.gonglei@...wei.com>,
        "Longpeng(Mike)" <longpeng2@...wei.com>
Subject: [PATCH 5.6 100/161] crypto: virtio: Fix src/dst scatterlist calculation in __virtio_crypto_skcipher_do_req()

From: Longpeng(Mike) <longpeng2@...wei.com>

commit b02989f37fc5e865ceeee9070907e4493b3a21e2 upstream.

The system will crash when the users insmod crypto/tcrypt.ko with mode=38
( testing "cts(cbc(aes))" ).

Usually the next entry of one sg will be @sg@ + 1, but if this sg element
is part of a chained scatterlist, it could jump to the start of a new
scatterlist array. Fix it by sg_next() on calculation of src/dst
scatterlist.

Fixes: dbaf0624ffa5 ("crypto: add virtio-crypto driver")
Reported-by: LABBE Corentin <clabbe@...libre.com>
Cc: Herbert Xu <herbert@...dor.apana.org.au>
Cc: "Michael S. Tsirkin" <mst@...hat.com>
Cc: Jason Wang <jasowang@...hat.com>
Cc: "David S. Miller" <davem@...emloft.net>
Cc: virtualization@...ts.linux-foundation.org
Cc: linux-kernel@...r.kernel.org
Cc: stable@...r.kernel.org
Link: https://lore.kernel.org/r/20200123101000.GB24255@Red
Signed-off-by: Gonglei <arei.gonglei@...wei.com>
Signed-off-by: Longpeng(Mike) <longpeng2@...wei.com>
Link: https://lore.kernel.org/r/20200602070501.2023-2-longpeng2@huawei.com
Signed-off-by: Michael S. Tsirkin <mst@...hat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/crypto/virtio/virtio_crypto_algs.c |   15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

--- a/drivers/crypto/virtio/virtio_crypto_algs.c
+++ b/drivers/crypto/virtio/virtio_crypto_algs.c
@@ -350,13 +350,18 @@ __virtio_crypto_skcipher_do_req(struct v
 	int err;
 	unsigned long flags;
 	struct scatterlist outhdr, iv_sg, status_sg, **sgs;
-	int i;
 	u64 dst_len;
 	unsigned int num_out = 0, num_in = 0;
 	int sg_total;
 	uint8_t *iv;
+	struct scatterlist *sg;

 	src_nents = sg_nents_for_len(req->src, req->cryptlen);
+	if (src_nents < 0) {
+		pr_err("Invalid number of src SG.\n");
+		return src_nents;
+	}
+
 	dst_nents = sg_nents(req->dst);

 	pr_debug("virtio_crypto: Number of sgs (src_nents: %d, dst_nents: %d)\n",
@@ -443,12 +448,12 @@ __virtio_crypto_skcipher_do_req(struct v
 	vc_sym_req->iv = iv;

 	/* Source data */
-	for (i = 0; i < src_nents; i++)
-		sgs[num_out++] = &req->src[i];
+	for (sg = req->src; src_nents; sg = sg_next(sg), src_nents--)
+		sgs[num_out++] = sg;

 	/* Destination data */
-	for (i = 0; i < dst_nents; i++)
-		sgs[num_out + num_in++] = &req->dst[i];
+	for (sg = req->dst; sg; sg = sg_next(sg))
+		sgs[num_out + num_in++] = sg;

 	/* Status */
 	sg_init_one(&status_sg, &vc_req->status, sizeof(vc_req->status));