From mboxrd@z Thu Jan 1 00:00:00 1970 From: Amit Shah Subject: Re: [PATCH 03/10] virtio: console: clean up port data immediately at time of unplug Date: Fri, 19 Jul 2013 10:32:52 +0530 Message-ID: <20130719050252.GA3087@amit-x200.redhat.com> References: <51E8B0CB.1060703@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <51E8B0CB.1060703@redhat.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: virtualization-bounces@lists.linux-foundation.org Errors-To: virtualization-bounces@lists.linux-foundation.org To: Jason Wang Cc: stable@vger.kernel.org, Virtualization List List-Id: virtualization@lists.linuxfoundation.org On (Fri) 19 Jul 2013 [11:21:47], Jason Wang wrote: > On 07/19/2013 04:16 AM, Amit Shah wrote: > > diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c > > index b04ec95..6bf0df3 100644 > > --- a/drivers/char/virtio_console.c > > +++ b/drivers/char/virtio_console.c > > @@ -1501,14 +1501,6 @@ static void remove_port(struct kref *kref) > > > > port = container_of(kref, struct port, kref); > > > > - sysfs_remove_group(&port->dev->kobj, &port_attribute_group); > > - device_destroy(pdrvdata.class, port->dev->devt); > > - cdev_del(port->cdev); > > - > > - kfree(port->name); > > - > > - debugfs_remove(port->debugfs_file); > > - > > kfree(port); > > } > > > > @@ -1566,6 +1558,14 @@ static void unplug_port(struct port *port) > > */ > > port->portdev = NULL; > > > > + sysfs_remove_group(&port->dev->kobj, &port_attribute_group); > > + device_destroy(pdrvdata.class, port->dev->devt); > > + cdev_del(port->cdev); > > + > > + kfree(port->name); > > + > > + debugfs_remove(port->debugfs_file); > > + > > /* > > * Locks around here are not necessary - a port can't be > > * opened after we removed the port struct from ports_list > > Should we remove debugfs file before kfree()? Otherwise looks like a > use-after-free if user access debugfs after kfree(). It is removed before kfree() -- kfree() is called in remove_port(), which is called when all the references are dropped. (Did you confuse kfree(port->name) with kfree(port)?) Thanks, Amit