From: Vitor Soares <Vitor.Soares@synopsys.com>
To: Boris Brezillon <boris.brezillon@collabora.com>
Cc: Jose Abreu <Jose.Abreu@synopsys.com>,
Joao Pinto <Joao.Pinto@synopsys.com>,
"arnd@arndb.de" <arnd@arndb.de>,
"corbet@lwn.net" <corbet@lwn.net>,
"gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>,
"wsa@the-dreams.de" <wsa@the-dreams.de>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"broonie@kernel.org" <broonie@kernel.org>,
"linux-i3c@lists.infradead.org" <linux-i3c@lists.infradead.org>,
"bbrezillon@kernel.org" <bbrezillon@kernel.org>
Subject: RE: [PATCH v3 4/5] i3c: add i3cdev module to expose i3c dev in /dev
Date: Mon, 24 Feb 2020 11:04:50 +0000 [thread overview]
Message-ID: <CH2PR12MB42163351853CCC029D28164BAEEC0@CH2PR12MB4216.namprd12.prod.outlook.com> (raw)
In-Reply-To: <20200221233216.3b2038f8@collabora.com>
Hi Boris,
From: Boris Brezillon <boris.brezillon@collabora.com>
Date: Fri, Feb 21, 2020 at 22:32:16
> On Wed, 19 Feb 2020 01:20:42 +0100
> Vitor Soares <Vitor.Soares@synopsys.com> wrote:
>
> > +static int i3cdev_detach(struct device *dev, void *dummy)
> > +{
> > + struct i3cdev_data *i3cdev;
> > + struct i3c_device *i3c;
> > +
> > + if (dev->type == &i3c_masterdev_type)
> > + return 0;
> > +
> > + i3c = dev_to_i3cdev(dev);
> > +
> > + i3cdev = i3cdev_get_drvdata(i3c);
> > + if (!i3cdev)
> > + return 0;
> > +
> > + /* Prevent transfers while cdev removal */
> > + mutex_lock(&i3cdev->xfer_lock);
> > + cdev_del(&i3cdev->cdev);
>
> When cdev_del() returns there might be opened FDs pointing to your
> i3cdev [1] ...
Yes, I know. I protected the driver part but I missed the
file->private_data.
>
> > + device_destroy(i3cdev_class, MKDEV(MAJOR(i3cdev_number), i3cdev->id));
> > + mutex_unlock(&i3cdev->xfer_lock);
> > +
> > + ida_simple_remove(&i3cdev_ida, i3cdev->id);
> > + put_i3cdev(i3cdev);
>
> ... and you call put_i3cdev() here which frees the i3cdev object,
> leading to potential use-after-free if any of the fops (ioctl, read,
> write) are called on those dangling FDs. That's exactly the kind of
> nightmare I'd like to avoid.
>
> > +
> > + pr_debug("i3cdev: device [%s] unregistered\n", dev_name(&i3c->dev));
> > +
> > + return 0;
> > +}
> > +
>
> [1]https://urldefense.proofpoint.com/v2/url?u=https-3A__elixir.bootlin.com_linux_latest_source_fs_char-5Fdev.c-23L587&d=DwICAg&c=DPL6_X_6JkXFx7AXWqB0tg&r=qVuU64u9x77Y0Kd0PhDK_lpxFgg6PK9PateHwjb_DY0&m=tn0F5CeiGtvih3B93GkstU1b2CzoxKklNq4vIvshH8I&s=FwSMjJ-YZFPUB6WCQM0KnFqFSVKp5KdKHdqSiu_0ycU&e=
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next prev parent reply other threads:[~2020-02-24 11:05 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-19 0:20 [PATCH v3 0/5] Introduce i3c device userspace interface Vitor Soares
2020-02-19 0:20 ` [PATCH v3 1/5] i3c: master: export i3c_masterdev_type Vitor Soares
2020-02-19 0:20 ` [PATCH v3 2/5] i3c: master: export i3c_bus_type symbol Vitor Soares
2020-02-19 0:20 ` [PATCH v3 3/5] i3c: master: add i3c_for_each_dev helper Vitor Soares
2020-02-19 7:35 ` Greg KH
2020-02-21 11:47 ` Vitor Soares
2020-02-21 11:52 ` Greg KH
2020-02-21 12:59 ` Boris Brezillon
2020-02-21 16:44 ` Boris Brezillon
2020-02-21 16:45 ` Boris Brezillon
2020-02-21 17:19 ` Vitor Soares
2020-02-22 8:38 ` Boris Brezillon
2020-02-19 0:20 ` [PATCH v3 4/5] i3c: add i3cdev module to expose i3c dev in /dev Vitor Soares
2020-02-19 7:37 ` Greg KH
2020-02-19 8:45 ` Vitor Soares
2020-02-19 7:39 ` Greg KH
2020-02-21 11:50 ` Vitor Soares
2020-02-19 8:42 ` Greg KH
2020-02-21 22:32 ` Boris Brezillon
2020-02-24 11:04 ` Vitor Soares [this message]
2020-02-24 11:22 ` Boris Brezillon
2020-02-19 0:20 ` [PATCH v3 5/5] add i3cdev documentation Vitor Soares
2020-02-19 0:46 ` Vitor Soares
2020-02-19 4:34 ` Randy Dunlap
2020-02-21 10:31 ` Vitor Soares
2020-02-21 15:36 ` Randy Dunlap
2020-02-19 0:39 ` [PATCH v3 0/5] Introduce i3c device userspace interface Vitor Soares
2020-02-19 8:16 ` Boris Brezillon
2020-02-21 17:08 ` Vitor Soares
2020-02-21 17:41 ` Boris Brezillon
2020-02-24 10:53 ` Vitor Soares
2020-02-24 11:24 ` Boris Brezillon
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