From d53c5135792319e095bb126bc43b2ee98586f7fe Mon Sep 17 00:00:00 2001
From: Stephan Mueller <smueller@chronox.de>
Date: Fri, 8 Dec 2017 11:50:37 +0100
Subject: [PATCH] crypto: af_alg - fix race accessing cipher request
Git-commit: d53c5135792319e095bb126bc43b2ee98586f7fe
Patch-mainline: v4.15-rc5
References: bsc#1154737

When invoking an asynchronous cipher operation, the invocation of the
callback may be performed before the subsequent operations in the
initial code path are invoked. The callback deletes the cipher request
data structure which implies that after the invocation of the
asynchronous cipher operation, this data structure must not be accessed
any more.

The setting of the return code size with the request data structure must
therefore be moved before the invocation of the asynchronous cipher
operation.

Fixes: e870456d8e7c ("crypto: algif_skcipher - overhaul memory management")
Fixes: d887c52d6ae4 ("crypto: algif_aead - overhaul memory management")
Reported-by: syzbot <syzkaller@googlegroups.com>
Cc: <stable@vger.kernel.org> # v4.14+
Signed-off-by: Stephan Mueller <smueller@chronox.de>
Acked-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 crypto/algif_aead.c     | 10 +++++-----
 crypto/algif_skcipher.c | 10 +++++-----
 2 files changed, 10 insertions(+), 10 deletions(-)

diff --git a/crypto/algif_aead.c b/crypto/algif_aead.c
index c8a32bef208a..b73db2b27656 100644
--- a/crypto/algif_aead.c
+++ b/crypto/algif_aead.c
@@ -291,6 +291,10 @@ static int _aead_recvmsg(struct socket *sock, struct msghdr *msg,
 		/* AIO operation */
 		sock_hold(sk);
 		areq->iocb = msg->msg_iocb;
+
+		/* Remember output size that will be generated. */
+		areq->outlen = outlen;
+
 		aead_request_set_callback(&areq->cra_u.aead_req,
 					  CRYPTO_TFM_REQ_MAY_BACKLOG,
 					  af_alg_async_cb, areq);
@@ -298,12 +302,8 @@ static int _aead_recvmsg(struct socket *sock, struct msghdr *msg,
 				 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;
-
+		if (err == -EINPROGRESS || err == -EBUSY)
 			return -EIOCBQUEUED;
-		}
 
 		sock_put(sk);
 	} else {
diff --git a/crypto/algif_skcipher.c b/crypto/algif_skcipher.c
index 6fb595cd63ac..baef9bfccdda 100644
--- a/crypto/algif_skcipher.c
+++ b/crypto/algif_skcipher.c
@@ -125,6 +125,10 @@ static int _skcipher_recvmsg(struct socket *sock, struct msghdr *msg,
 		/* AIO operation */
 		sock_hold(sk);
 		areq->iocb = msg->msg_iocb;
+
+		/* Remember output size that will be generated. */
+		areq->outlen = len;
+
 		skcipher_request_set_callback(&areq->cra_u.skcipher_req,
 					      CRYPTO_TFM_REQ_MAY_SLEEP,
 					      af_alg_async_cb, areq);
@@ -133,12 +137,8 @@ static int _skcipher_recvmsg(struct socket *sock, struct msghdr *msg,
 			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;
-
+		if (err == -EINPROGRESS || err == -EBUSY)
 			return -EIOCBQUEUED;
-		}
 
 		sock_put(sk);
 	} else {
-- 
2.16.4