From: Boris Brezillon <boris.brezillon@collabora.com>
To: Vitor Soares <Vitor.Soares@synopsys.com>
Cc: Jose.Abreu@synopsys.com, Joao.Pinto@synopsys.com, arnd@arndb.de,
corbet@lwn.net, gregkh@linuxfoundation.org, wsa@the-dreams.de,
linux-kernel@vger.kernel.org, broonie@kernel.org,
linux-i3c@lists.infradead.org, bbrezillon@kernel.org
Subject: Re: [PATCH v3 4/5] i3c: add i3cdev module to expose i3c dev in /dev
Date: Fri, 21 Feb 2020 23:32:16 +0100 [thread overview]
Message-ID: <20200221233216.3b2038f8@collabora.com> (raw)
In-Reply-To: <e093ae9da81e7702c188a20d1e8b9d7f8024bfeb.1582069402.git.vitor.soares@synopsys.com>
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] ...
> + 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://elixir.bootlin.com/linux/latest/source/fs/char_dev.c#L587
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next prev parent reply other threads:[~2020-02-21 22:32 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 [this message]
2020-02-24 11:04 ` Vitor Soares
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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