* [PATCH 0/2] gpio: regression fixes
@ 2021-02-26 14:52 Johan Hovold
2021-02-26 14:52 ` [PATCH 1/2] gpio: fix NULL-deref-on-deregistration regression Johan Hovold
2021-02-26 14:52 ` [PATCH 2/2] gpio: fix gpio-device list corruption Johan Hovold
0 siblings, 2 replies; 6+ messages in thread
From: Johan Hovold @ 2021-02-26 14:52 UTC (permalink / raw
To: Linus Walleij, Bartosz Golaszewski
Cc: Greg Kroah-Hartman, Saravana Kannan, linux-gpio, linux-kernel,
Johan Hovold
Here's a fix for a regression in 5.12 due to the new stub-driver hack,
and a fix for potential list corruption due to missing locking which has
been there since the introduction of the character-device interface in
4.6.
Johan
Johan Hovold (2):
gpio: fix NULL-deref-on-deregistration regression
gpio: fix gpio-device list corruption
drivers/gpio/gpiolib.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
--
2.26.2
^ permalink raw reply [flat|nested] 6+ messages in thread
* [PATCH 1/2] gpio: fix NULL-deref-on-deregistration regression
2021-02-26 14:52 [PATCH 0/2] gpio: regression fixes Johan Hovold
@ 2021-02-26 14:52 ` Johan Hovold
2021-02-26 21:54 ` Saravana Kannan
2021-02-26 14:52 ` [PATCH 2/2] gpio: fix gpio-device list corruption Johan Hovold
1 sibling, 1 reply; 6+ messages in thread
From: Johan Hovold @ 2021-02-26 14:52 UTC (permalink / raw
To: Linus Walleij, Bartosz Golaszewski
Cc: Greg Kroah-Hartman, Saravana Kannan, linux-gpio, linux-kernel,
Johan Hovold, syzbot+d27b4c8adbbff70fbfde
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);
list_del(&gdev->list);
ida_free(&gpio_ida, gdev->id);
--
2.26.2
^ permalink raw reply related [flat|nested] 6+ messages in thread
* [PATCH 2/2] gpio: fix gpio-device list corruption
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 14:52 ` Johan Hovold
2021-02-26 20:59 ` Saravana Kannan
1 sibling, 1 reply; 6+ messages in thread
From: Johan Hovold @ 2021-02-26 14:52 UTC (permalink / raw
To: Linus Walleij, Bartosz Golaszewski
Cc: Greg Kroah-Hartman, Saravana Kannan, linux-gpio, linux-kernel,
Johan Hovold, stable
Make sure to hold the gpio_lock when removing the gpio device from the
gpio_devices list (when dropping the last reference) to avoid corrupting
the list when there are concurrent accesses.
Fixes: ff2b13592299 ("gpio: make the gpiochip a real device")
Cc: stable@vger.kernel.org # 4.6
Signed-off-by: Johan Hovold <johan@kernel.org>
---
drivers/gpio/gpiolib.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index e1016bc8cf14..42bdc55a15f9 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -475,8 +475,12 @@ EXPORT_SYMBOL_GPL(gpiochip_line_is_valid);
static void gpiodevice_release(struct device *dev)
{
struct gpio_device *gdev = container_of(dev, struct gpio_device, dev);
+ unsigned long flags;
+ spin_lock_irqsave(&gpio_lock, flags);
list_del(&gdev->list);
+ spin_unlock_irqrestore(&gpio_lock, flags);
+
ida_free(&gpio_ida, gdev->id);
kfree_const(gdev->label);
kfree(gdev->descs);
--
2.26.2
^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH 2/2] gpio: fix gpio-device list corruption
2021-02-26 14:52 ` [PATCH 2/2] gpio: fix gpio-device list corruption Johan Hovold
@ 2021-02-26 20:59 ` Saravana Kannan
0 siblings, 0 replies; 6+ messages in thread
From: Saravana Kannan @ 2021-02-26 20:59 UTC (permalink / raw
To: Johan Hovold
Cc: Linus Walleij, Bartosz Golaszewski, Greg Kroah-Hartman,
open list:GPIO SUBSYSTEM, LKML, stable
On Fri, Feb 26, 2021 at 6:55 AM Johan Hovold <johan@kernel.org> wrote:
>
> Make sure to hold the gpio_lock when removing the gpio device from the
> gpio_devices list (when dropping the last reference) to avoid corrupting
> the list when there are concurrent accesses.
>
> Fixes: ff2b13592299 ("gpio: make the gpiochip a real device")
> Cc: stable@vger.kernel.org # 4.6
> Signed-off-by: Johan Hovold <johan@kernel.org>
> ---
> drivers/gpio/gpiolib.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
> index e1016bc8cf14..42bdc55a15f9 100644
> --- a/drivers/gpio/gpiolib.c
> +++ b/drivers/gpio/gpiolib.c
> @@ -475,8 +475,12 @@ EXPORT_SYMBOL_GPL(gpiochip_line_is_valid);
> static void gpiodevice_release(struct device *dev)
> {
> struct gpio_device *gdev = container_of(dev, struct gpio_device, dev);
> + unsigned long flags;
>
> + spin_lock_irqsave(&gpio_lock, flags);
> list_del(&gdev->list);
> + spin_unlock_irqrestore(&gpio_lock, flags);
> +
Reviewed-by: Saravana Kannan <saravanak@google.com>
-Saravana
> ida_free(&gpio_ida, gdev->id);
> kfree_const(gdev->label);
> kfree(gdev->descs);
> --
> 2.26.2
>
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH 1/2] gpio: fix NULL-deref-on-deregistration regression
2021-02-26 14:52 ` [PATCH 1/2] gpio: fix NULL-deref-on-deregistration regression Johan Hovold
@ 2021-02-26 21:54 ` Saravana Kannan
2021-03-01 8:44 ` Johan Hovold
0 siblings, 1 reply; 6+ messages in thread
From: Saravana Kannan @ 2021-02-26 21:54 UTC (permalink / raw
To: Johan Hovold
Cc: Linus Walleij, Bartosz Golaszewski, Greg Kroah-Hartman,
open list:GPIO SUBSYSTEM, LKML, syzbot+d27b4c8adbbff70fbfde
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
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH 1/2] gpio: fix NULL-deref-on-deregistration regression
2021-02-26 21:54 ` Saravana Kannan
@ 2021-03-01 8:44 ` Johan Hovold
0 siblings, 0 replies; 6+ messages in thread
From: Johan Hovold @ 2021-03-01 8:44 UTC (permalink / raw
To: Saravana Kannan
Cc: Linus Walleij, Bartosz Golaszewski, Greg Kroah-Hartman,
open list:GPIO SUBSYSTEM, LKML, syzbot+d27b4c8adbbff70fbfde
On Fri, Feb 26, 2021 at 01:54:12PM -0800, Saravana Kannan wrote:
> 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.
Yeah, I considered it but didn't want to risk introducing any new
regressions just to clean up a redundant store.
But looking at it again today, I agree that it looks like it isn't used
anywhere else. I'll send a v2. Thanks.
Johan
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2021-03-01 8:45 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz follow: Atom feed
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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
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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