From: Saravana Kannan <saravanak@google.com>
To: Johan Hovold <johan@kernel.org>
Cc: Linus Walleij <linus.walleij@linaro.org>,
Bartosz Golaszewski <bgolaszewski@baylibre.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
"open list:GPIO SUBSYSTEM" <linux-gpio@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
syzbot+d27b4c8adbbff70fbfde@syzkaller.appspotmail.com
Subject: Re: [PATCH 1/2] gpio: fix NULL-deref-on-deregistration regression
Date: Fri, 26 Feb 2021 13:54:12 -0800 [thread overview]
Message-ID: <CAGETcx-4Q+SkdLO-rXE-zt2kdz=J1cnrPjv07mt0KRtCPa_OGg@mail.gmail.com> (raw)
In-Reply-To: <20210226145246.1171-2-johan@kernel.org>
On Fri, Feb 26, 2021 at 6:55 AM Johan Hovold <johan@kernel.org> wrote:
>
> Fix a NULL-pointer deference when deregistering the gpio character
> device that was introduced by the recent stub-driver hack. When the new
> "driver" is unbound as part of deregistration, driver core clears the
> driver-data pointer which is used to retrieve the struct gpio_device in
> its release callback.
>
> Fix this by using container_of() in the release callback as should have
> been done all along.
>
> Fixes: 4731210c09f5 ("gpiolib: Bind gpio_device to a driver to enable fw_devlink=on by default")
> Cc: Saravana Kannan <saravanak@google.com>
> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Reported-by: syzbot+d27b4c8adbbff70fbfde@syzkaller.appspotmail.com
> Signed-off-by: Johan Hovold <johan@kernel.org>
> ---
> drivers/gpio/gpiolib.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
> index adf55db080d8..e1016bc8cf14 100644
> --- a/drivers/gpio/gpiolib.c
> +++ b/drivers/gpio/gpiolib.c
> @@ -474,7 +474,7 @@ EXPORT_SYMBOL_GPL(gpiochip_line_is_valid);
>
> static void gpiodevice_release(struct device *dev)
> {
> - struct gpio_device *gdev = dev_get_drvdata(dev);
> + struct gpio_device *gdev = container_of(dev, struct gpio_device, dev);
Can you also delete the dev_set_drvdata() in
gpiochip_add_data_with_key() if the drvdata is not used
elsewhere anymore? I skimmed the code and it doesn't look like it, but
I could be wrong.
-Saravana
next prev parent reply other threads:[~2021-02-26 21:55 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-26 14:52 [PATCH 0/2] gpio: regression fixes Johan Hovold
2021-02-26 14:52 ` [PATCH 1/2] gpio: fix NULL-deref-on-deregistration regression Johan Hovold
2021-02-26 21:54 ` Saravana Kannan [this message]
2021-03-01 8:44 ` Johan Hovold
2021-02-26 14:52 ` [PATCH 2/2] gpio: fix gpio-device list corruption Johan Hovold
2021-02-26 20:59 ` Saravana Kannan
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