[4.2.y-ckt stable] Patch "crypto: algif_skcipher - Do not assume that req is unchanged" has been added to the 4.2.y-ckt tree

[Kamal Mostafa]

This is a note to let you know that I have just added a patch titled

    crypto: algif_skcipher - Do not assume that req is unchanged

to the linux-4.2.y-queue branch of the 4.2.y-ckt extended stable tree 
which can be found at:

    http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-4.2.y-queue

This patch is scheduled to be released in version 4.2.8-ckt7.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 4.2.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

---8<------------------------------------------------------------

>From c6b3e7a06dadfa5948bfb5553ccc77eb5fead6de Mon Sep 17 00:00:00 2001
From: Herbert Xu <herbert at gondor.apana.org.au>
Date: Wed, 3 Feb 2016 21:39:24 +0800
Subject: crypto: algif_skcipher - Do not assume that req is unchanged

commit ec69bbfb9902c32a5c1492f2b1b8ad032a66d724 upstream.

The async path in algif_skcipher assumes that the crypto completion
function will be called with the original request.  This is not
necessarily the case.  In fact there is no need for this anyway
since we already embed information into the request with struct
skcipher_async_req.

This patch adds a pointer to that struct and then passes it as
the data to the callback function.

Signed-off-by: Herbert Xu <herbert at gondor.apana.org.au>
Tested-by: Tadeusz Struk <tadeusz.struk at intel.com>
[ kamal: backport to 4.2-stable: use ablkcipher ]
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 crypto/algif_skcipher.c | 60 +++++++++++++++++++++++--------------------------
 1 file changed, 28 insertions(+), 32 deletions(-)

diff --git a/crypto/algif_skcipher.c b/crypto/algif_skcipher.c
index b5d5a35..1939e60 100644
--- a/crypto/algif_skcipher.c
+++ b/crypto/algif_skcipher.c
@@ -65,18 +65,10 @@ struct skcipher_async_req {
 	struct skcipher_async_rsgl first_sgl;
 	struct list_head list;
 	struct scatterlist *tsg;
-	char iv[];
+	atomic_t *inflight;
+	struct ablkcipher_request req;
 };

-#define GET_SREQ(areq, ctx) (struct skcipher_async_req *)((char *)areq + \
-	crypto_ablkcipher_reqsize(crypto_ablkcipher_reqtfm(&ctx->req)))
-
-#define GET_REQ_SIZE(ctx) \
-	crypto_ablkcipher_reqsize(crypto_ablkcipher_reqtfm(&ctx->req))
-
-#define GET_IV_SIZE(ctx) \
-	crypto_ablkcipher_ivsize(crypto_ablkcipher_reqtfm(&ctx->req))
-
 #define MAX_SGL_ENTS ((4096 - sizeof(struct skcipher_sg_list)) / \
 		      sizeof(struct scatterlist) - 1)

@@ -102,15 +94,12 @@ static void skcipher_free_async_sgls(struct skcipher_async_req *sreq)

 static void skcipher_async_cb(struct crypto_async_request *req, int err)
 {
-	struct sock *sk = req->data;
-	struct alg_sock *ask = alg_sk(sk);
-	struct skcipher_ctx *ctx = ask->private;
-	struct skcipher_async_req *sreq = GET_SREQ(req, ctx);
+	struct skcipher_async_req *sreq = req->data;
 	struct kiocb *iocb = sreq->iocb;

-	atomic_dec(&ctx->inflight);
+	atomic_dec(sreq->inflight);
 	skcipher_free_async_sgls(sreq);
-	kfree(req);
+	kzfree(sreq);
 	iocb->ki_complete(iocb, err, err);
 }

@@ -509,37 +498,42 @@ static int skcipher_recvmsg_async(struct socket *sock, struct msghdr *msg,
 {
 	struct sock *sk = sock->sk;
 	struct alg_sock *ask = alg_sk(sk);
+	struct sock *psk = ask->parent;
+	struct alg_sock *pask = alg_sk(psk);
 	struct skcipher_ctx *ctx = ask->private;
+	struct skcipher_tfm *skc = pask->private;
+	struct crypto_ablkcipher *tfm = skc->skcipher;
 	struct skcipher_sg_list *sgl;
 	struct scatterlist *sg;
 	struct skcipher_async_req *sreq;
 	struct ablkcipher_request *req;
 	struct skcipher_async_rsgl *last_rsgl = NULL;
 	unsigned int txbufs = 0, len = 0, tx_nents = skcipher_all_sg_nents(ctx);
-	unsigned int reqlen = sizeof(struct skcipher_async_req) +
-				GET_REQ_SIZE(ctx) + GET_IV_SIZE(ctx);
+	unsigned int reqsize = crypto_ablkcipher_reqsize(tfm);
+	unsigned int ivsize = crypto_ablkcipher_ivsize(tfm);
 	int err = -ENOMEM;
 	bool mark = false;
+	char *iv;

-	lock_sock(sk);
-	req = kmalloc(reqlen, GFP_KERNEL);
-	if (unlikely(!req))
-		goto unlock;
+	sreq = kzalloc(sizeof(*sreq) + reqsize + ivsize, GFP_KERNEL);
+	if (unlikely(!sreq))
+		goto out;

-	sreq = GET_SREQ(req, ctx);
+	req = &sreq->req;
+	iv = (char *)(req + 1) + reqsize;
 	sreq->iocb = msg->msg_iocb;
-	memset(&sreq->first_sgl, '\0', sizeof(struct skcipher_async_rsgl));
 	INIT_LIST_HEAD(&sreq->list);
+	sreq->inflight = &ctx->inflight;
+
+	lock_sock(sk);
 	sreq->tsg = kcalloc(tx_nents, sizeof(*sg), GFP_KERNEL);
-	if (unlikely(!sreq->tsg)) {
-		kfree(req);
+	if (unlikely(!sreq->tsg))
 		goto unlock;
-	}
 	sg_init_table(sreq->tsg, tx_nents);
-	memcpy(sreq->iv, ctx->iv, GET_IV_SIZE(ctx));
-	ablkcipher_request_set_tfm(req, crypto_ablkcipher_reqtfm(&ctx->req));
+	memcpy(iv, ctx->iv, ivsize);
+	ablkcipher_request_set_tfm(req, tfm);
 	ablkcipher_request_set_callback(req, CRYPTO_TFM_REQ_MAY_SLEEP,
-					skcipher_async_cb, sk);
+				        skcipher_async_cb, sreq);

 	while (iov_iter_count(&msg->msg_iter)) {
 		struct skcipher_async_rsgl *rsgl;
@@ -615,20 +609,22 @@ static int skcipher_recvmsg_async(struct socket *sock, struct msghdr *msg,
 		sg_mark_end(sreq->tsg + txbufs - 1);

 	ablkcipher_request_set_crypt(req, sreq->tsg, sreq->first_sgl.sgl.sg,
-				     len, sreq->iv);
+				     len, iv);
 	err = ctx->enc ? crypto_ablkcipher_encrypt(req) :
 			 crypto_ablkcipher_decrypt(req);
 	if (err == -EINPROGRESS) {
 		atomic_inc(&ctx->inflight);
 		err = -EIOCBQUEUED;
+		sreq = NULL;
 		goto unlock;
 	}
 free:
 	skcipher_free_async_sgls(sreq);
-	kfree(req);
 unlock:
 	skcipher_wmem_wakeup(sk);
 	release_sock(sk);
+	kzfree(sreq);
+out:
 	return err;
 }

--
2.7.0