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Subject[PATCH v2 1/2] crypto: virtio: Fix src/dst scatterlist calculation in __virtio_crypto_skcipher_do_req()
Date
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@baylibre.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Jason Wang <jasowang@redhat.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Markus Elfring <Markus.Elfring@web.de>
Cc: virtualization@lists.linux-foundation.org
Cc: linux-kernel@vger.kernel.org
Cc: stable@vger.kernel.org
Message-Id: <20200123101000.GB24255@Red>
Signed-off-by: Gonglei <arei.gonglei@huawei.com>
Signed-off-by: Longpeng(Mike) <longpeng2@huawei.com>
---
drivers/crypto/virtio/virtio_crypto_algs.c | 15 ++++++++++-----
1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/drivers/crypto/virtio/virtio_crypto_algs.c b/drivers/crypto/virtio/virtio_crypto_algs.c
index fd045e64972a..5f8243563009 100644
--- 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 virtio_crypto_sym_request *vc_sym_req,
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",
@@ -442,12 +447,12 @@ __virtio_crypto_skcipher_do_req(struct virtio_crypto_sym_request *vc_sym_req,
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));
--
2.23.0
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