FAILED: patch "[PATCH] crypto: algif_skcipher - Do not dereference ctx without" failed to apply to 3.10-stable tree

[<gregkh@linuxfoundation.org>]

The patch below does not apply to the 3.10-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

>From 6454c2b83f719057069777132b13949e4c6b6350 Mon Sep 17 00:00:00 2001
From: Herbert Xu <herbert@gondor.apana.org.au>
Date: Wed, 3 Feb 2016 21:39:26 +0800
Subject: [PATCH] crypto: algif_skcipher - Do not dereference ctx without
 socket lock

Any access to non-constant bits of the private context must be
done under the socket lock, in particular, this includes ctx->req.

This patch moves such accesses under the lock, and fetches the
tfm from the parent socket which is guaranteed to be constant,
rather than from ctx->req.

Cc: stable@vger.kernel.org
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

diff --git a/crypto/algif_skcipher.c b/crypto/algif_skcipher.c
index ec07a864b9c5..ef84353e0f24 100644
--- a/crypto/algif_skcipher.c
+++ b/crypto/algif_skcipher.c
@@ -295,8 +295,11 @@ static int skcipher_sendmsg(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 crypto_skcipher *tfm = crypto_skcipher_reqtfm(&ctx->req);
+	struct skcipher_tfm *skc = pask->private;
+	struct crypto_skcipher *tfm = skc->skcipher;
 	unsigned ivsize = crypto_skcipher_ivsize(tfm);
 	struct skcipher_sg_list *sgl;
 	struct af_alg_control con = {};
@@ -508,7 +511,7 @@ static int skcipher_recvmsg_async(struct socket *sock, struct msghdr *msg,
 	struct skcipher_async_req *sreq;
 	struct skcipher_request *req;
 	struct skcipher_async_rsgl *last_rsgl = NULL;
-	unsigned int txbufs = 0, len = 0, tx_nents = skcipher_all_sg_nents(ctx);
+	unsigned int txbufs = 0, len = 0, tx_nents;
 	unsigned int reqsize = crypto_skcipher_reqsize(tfm);
 	unsigned int ivsize = crypto_skcipher_ivsize(tfm);
 	int err = -ENOMEM;
@@ -526,6 +529,7 @@ static int skcipher_recvmsg_async(struct socket *sock, struct msghdr *msg,
 	sreq->inflight = &ctx->inflight;
 
 	lock_sock(sk);
+	tx_nents = skcipher_all_sg_nents(ctx);
 	sreq->tsg = kcalloc(tx_nents, sizeof(*sg), GFP_KERNEL);
 	if (unlikely(!sreq->tsg))
 		goto unlock;
@@ -633,9 +637,12 @@ static int skcipher_recvmsg_sync(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;
-	unsigned bs = crypto_skcipher_blocksize(crypto_skcipher_reqtfm(
-		&ctx->req));
+	struct skcipher_tfm *skc = pask->private;
+	struct crypto_skcipher *tfm = skc->skcipher;
+	unsigned bs = crypto_skcipher_blocksize(tfm);
 	struct skcipher_sg_list *sgl;
 	struct scatterlist *sg;
 	int err = -EAGAIN;