This is a note to let you know that I've just added the patch titled

crypto: af_alg - remove locking in async callback

to the 4.14-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...

The filename of the patch is: crypto-af_alg-remove-locking-in-async-callback.patch and it can be found in the queue-4.14 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.

From 7d2c3f54e6f646887d019faa45f35d6fe9fe82ce Mon Sep 17 00:00:00 2001

From: Stephan Mueller smueller@chronox.de Date: Fri, 10 Nov 2017 13:20:55 +0100 Subject: crypto: af_alg - remove locking in async callback

From: Stephan Mueller smueller@chronox.de

commit 7d2c3f54e6f646887d019faa45f35d6fe9fe82ce upstream.

The code paths protected by the socket-lock do not use or modify the socket in a non-atomic fashion. The actions pertaining the socket do not even need to be handled as an atomic operation. Thus, the socket-lock can be safely ignored.

This fixes a bug regarding scheduling in atomic as the callback function may be invoked in interrupt context.

In addition, the sock_hold is moved before the AIO encrypt/decrypt operation to ensure that the socket is always present. This avoids a tiny race window where the socket is unprotected and yet used by the AIO operation.

Finally, the release of resources for a crypto operation is moved into a common function of af_alg_free_resources.

Fixes: e870456d8e7c8 ("crypto: algif_skcipher - overhaul memory management") Fixes: d887c52d6ae43 ("crypto: algif_aead - overhaul memory management") Reported-by: Romain Izard romain.izard.pro@gmail.com Signed-off-by: Stephan Mueller smueller@chronox.de Tested-by: Romain Izard romain.izard.pro@gmail.com Signed-off-by: Herbert Xu herbert@gondor.apana.org.au Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org

--- crypto/af_alg.c | 21 ++++++++++++++------- crypto/algif_aead.c | 23 ++++++++++++----------- crypto/algif_skcipher.c | 23 ++++++++++++----------- include/crypto/if_alg.h | 1 + 4 files changed, 39 insertions(+), 29 deletions(-)

--- a/crypto/af_alg.c +++ b/crypto/af_alg.c @@ -1048,6 +1048,18 @@ unlock: EXPORT_SYMBOL_GPL(af_alg_sendpage);

/** + * af_alg_free_resources - release resources required for crypto request + */ +void af_alg_free_resources(struct af_alg_async_req *areq) +{ + struct sock *sk = areq->sk; + + af_alg_free_areq_sgls(areq); + sock_kfree_s(sk, areq, areq->areqlen); +} +EXPORT_SYMBOL_GPL(af_alg_free_resources); + +/** * af_alg_async_cb - AIO callback handler * * This handler cleans up the struct af_alg_async_req upon completion of the @@ -1063,18 +1075,13 @@ void af_alg_async_cb(struct crypto_async struct kiocb *iocb = areq->iocb; unsigned int resultlen;

- lock_sock(sk); - /* Buffer size written by crypto operation. */ resultlen = areq->outlen;

- af_alg_free_areq_sgls(areq); - sock_kfree_s(sk, areq, areq->areqlen); - __sock_put(sk); + af_alg_free_resources(areq); + sock_put(sk);

iocb->ki_complete(iocb, err ? err : resultlen, 0); - - release_sock(sk); } EXPORT_SYMBOL_GPL(af_alg_async_cb);

--- a/crypto/algif_aead.c +++ b/crypto/algif_aead.c @@ -283,12 +283,23 @@ static int _aead_recvmsg(struct socket *

if (msg->msg_iocb && !is_sync_kiocb(msg->msg_iocb)) { /* AIO operation */ + sock_hold(sk); areq->iocb = msg->msg_iocb; aead_request_set_callback(&areq->cra_u.aead_req, CRYPTO_TFM_REQ_MAY_BACKLOG, af_alg_async_cb, areq); err = ctx->enc ? crypto_aead_encrypt(&areq->cra_u.aead_req) : crypto_aead_decrypt(&areq->cra_u.aead_req); + + /* AIO operation in progress */ + if (err == -EINPROGRESS || err == -EBUSY) { + /* Remember output size that will be generated. */ + areq->outlen = outlen; + + return -EIOCBQUEUED; + } + + sock_put(sk); } else { /* Synchronous operation */ aead_request_set_callback(&areq->cra_u.aead_req, @@ -300,19 +311,9 @@ static int _aead_recvmsg(struct socket * &ctx->completion); }

- /* AIO operation in progress */ - if (err == -EINPROGRESS) { - sock_hold(sk); - - /* Remember output size that will be generated. */ - areq->outlen = outlen; - - return -EIOCBQUEUED; - }

free: - af_alg_free_areq_sgls(areq); - sock_kfree_s(sk, areq, areq->areqlen); + af_alg_free_resources(areq);

return err ? err : outlen; } --- a/crypto/algif_skcipher.c +++ b/crypto/algif_skcipher.c @@ -117,6 +117,7 @@ static int _skcipher_recvmsg(struct sock

if (msg->msg_iocb && !is_sync_kiocb(msg->msg_iocb)) { /* AIO operation */ + sock_hold(sk); areq->iocb = msg->msg_iocb; skcipher_request_set_callback(&areq->cra_u.skcipher_req, CRYPTO_TFM_REQ_MAY_SLEEP, @@ -124,6 +125,16 @@ static int _skcipher_recvmsg(struct sock err = ctx->enc ? crypto_skcipher_encrypt(&areq->cra_u.skcipher_req) : crypto_skcipher_decrypt(&areq->cra_u.skcipher_req); + + /* AIO operation in progress */ + if (err == -EINPROGRESS || err == -EBUSY) { + /* Remember output size that will be generated. */ + areq->outlen = len; + + return -EIOCBQUEUED; + } + + sock_put(sk); } else { /* Synchronous operation */ skcipher_request_set_callback(&areq->cra_u.skcipher_req, @@ -137,19 +148,9 @@ static int _skcipher_recvmsg(struct sock &ctx->completion); }

- /* AIO operation in progress */ - if (err == -EINPROGRESS) { - sock_hold(sk); - - /* Remember output size that will be generated. */ - areq->outlen = len; - - return -EIOCBQUEUED; - }

free: - af_alg_free_areq_sgls(areq); - sock_kfree_s(sk, areq, areq->areqlen); + af_alg_free_resources(areq);

return err ? err : len; } --- a/include/crypto/if_alg.h +++ b/include/crypto/if_alg.h @@ -255,6 +255,7 @@ int af_alg_sendmsg(struct socket *sock, unsigned int ivsize); ssize_t af_alg_sendpage(struct socket *sock, struct page *page, int offset, size_t size, int flags); +void af_alg_free_resources(struct af_alg_async_req *areq); void af_alg_async_cb(struct crypto_async_request *_req, int err); unsigned int af_alg_poll(struct file *file, struct socket *sock, poll_table *wait);

Patches currently in stable-queue which might be from smueller@chronox.de are

queue-4.14/crypto-af_alg-remove-locking-in-async-callback.patch queue-4.14/crypto-algif_aead-skip-sgl-entries-with-null-page.patch