linux-kernel - [PATCH net-next 2/3] vsock: fix vsock_dequeue/enqueue

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Date:   Tue, 15 Aug 2017 22:15:39 +0000
From:   Dexuan Cui <decui@...rosoft.com>
To:     "davem@...emloft.net" <davem@...emloft.net>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>
CC:     "'gregkh@...uxfoundation.org'" <'gregkh@...uxfoundation.org'>,
        "devel@...uxdriverproject.org" <devel@...uxdriverproject.org>,
        KY Srinivasan <kys@...rosoft.com>,
        Haiyang Zhang <haiyangz@...rosoft.com>,
        "Stephen Hemminger" <sthemmin@...rosoft.com>,
        George Zhang <georgezhang@...are.com>,
        Jorgen Hansen <jhansen@...are.com>,
        Michal Kubecek <mkubecek@...e.cz>,
        "Asias He" <asias@...hat.com>,
        Stefan Hajnoczi <stefanha@...hat.com>,
        "Vitaly Kuznetsov" <vkuznets@...hat.com>,
        Cathy Avery <cavery@...hat.com>,
        "jasowang@...hat.com" <jasowang@...hat.com>,
        Rolf Neugebauer <rolf.neugebauer@...ker.com>,
        Dave Scott <dave.scott@...ker.com>,
        "Marcelo Cerri" <marcelo.cerri@...onical.com>,
        "apw@...onical.com" <apw@...onical.com>,
        "olaf@...fle.de" <olaf@...fle.de>,
        "joe@...ches.com" <joe@...ches.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Dan Carpenter <dan.carpenter@...cle.com>
Subject: [PATCH net-next 2/3] vsock: fix vsock_dequeue/enqueue_accept race


With the current code, when vsock_dequeue_accept() is removing a sock
from the list, nothing prevents vsock_enqueue_accept() from adding a new
sock into the list concurrently. We should add a lock to protect the list.

Signed-off-by: Dexuan Cui <decui@...rosoft.com>
Cc: Andy King <acking@...are.com>
Cc: Dmitry Torokhov <dtor@...are.com>
Cc: George Zhang <georgezhang@...are.com>
Cc: Jorgen Hansen <jhansen@...are.com>
Cc: Reilly Grant <grantr@...are.com>
Cc: Asias He <asias@...hat.com>
Cc: Stefan Hajnoczi <stefanha@...hat.com>
Cc: Vitaly Kuznetsov <vkuznets@...hat.com>
Cc: Cathy Avery <cavery@...hat.com>
Cc: K. Y. Srinivasan <kys@...rosoft.com>
Cc: Haiyang Zhang <haiyangz@...rosoft.com>
Cc: Stephen Hemminger <sthemmin@...rosoft.com>
---
 net/vmw_vsock/af_vsock.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c
index dfc8c51e..b7b2c66 100644
--- a/net/vmw_vsock/af_vsock.c
+++ b/net/vmw_vsock/af_vsock.c
@@ -126,6 +126,7 @@ static struct proto vsock_proto = {
 
 static const struct vsock_transport *transport;
 static DEFINE_MUTEX(vsock_register_mutex);
+static DEFINE_SPINLOCK(vsock_accept_queue_lock);
 
 /**** EXPORTS ****/
 
@@ -406,7 +407,10 @@ void vsock_enqueue_accept(struct sock *listener, struct sock *connected)
 
 	sock_hold(connected);
 	sock_hold(listener);
+
+	spin_lock(&vsock_accept_queue_lock);
 	list_add_tail(&vconnected->accept_queue, &vlistener->accept_queue);
+	spin_unlock(&vsock_accept_queue_lock);
 }
 EXPORT_SYMBOL_GPL(vsock_enqueue_accept);
 
@@ -423,7 +427,10 @@ static struct sock *vsock_dequeue_accept(struct sock *listener)
 	vconnected = list_entry(vlistener->accept_queue.next,
 				struct vsock_sock, accept_queue);
 
+	spin_lock(&vsock_accept_queue_lock);
 	list_del_init(&vconnected->accept_queue);
+	spin_unlock(&vsock_accept_queue_lock);
+
 	sock_put(listener);
 	/* The caller will need a reference on the connected socket so we let
 	 * it call sock_put().
-- 
2.7.4