[PATCH 4.4 107/117] crypto: algif_skcipher - Do not dereference ctx without socket lock

Greg Kroah-Hartman
2016-02-14T23:19:43Z

From: Herbert Xu <herbert@gondor.apana.org.au>

commit 6454c2b83f719057069777132b13949e4c6b6350 upstream.

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.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
crypto/algif_skcipher.c | 15 +++++++++++----
1 file changed, 11 insertions(+), 4 deletions(-)

--- a/crypto/algif_skcipher.c
+++ b/crypto/algif_skcipher.c
@@ -295,8 +295,11 @@ static int skcipher_sendmsg(struct socke
{
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
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
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
{
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;