Linux-i3c Archive on lore.kernel.org
 help / color / Atom feed
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
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= 



_______________________________________________
linux-i3c mailing list
linux-i3c@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-i3c

  reply index

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

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=CH2PR12MB42163351853CCC029D28164BAEEC0@CH2PR12MB4216.namprd12.prod.outlook.com \
    --to=vitor.soares@synopsys.com \
    --cc=Joao.Pinto@synopsys.com \
    --cc=Jose.Abreu@synopsys.com \
    --cc=arnd@arndb.de \
    --cc=bbrezillon@kernel.org \
    --cc=boris.brezillon@collabora.com \
    --cc=broonie@kernel.org \
    --cc=corbet@lwn.net \
    --cc=gregkh@linuxfoundation.org \
    --cc=linux-i3c@lists.infradead.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=wsa@the-dreams.de \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

Linux-i3c Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-i3c/0 linux-i3c/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-i3c linux-i3c/ https://lore.kernel.org/linux-i3c \
		linux-i3c@lists.infradead.org
	public-inbox-index linux-i3c

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.infradead.lists.linux-i3c


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git