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gpio: fix NULL-deref-on-deregistration regression 

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: 4731210c09 ("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>
Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
This commit is contained in:
Johan Hovold 2021-03-01 10:05:18 +01:00 committed by Bartosz Golaszewski
parent 542104ee0c
commit a6112998ee
1 changed files with 1 additions and 2 deletions
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3
drivers/gpio/gpiolib.c
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@ -474,7 +474,7 @@ EXPORT_SYMBOL_GPL(gpiochip_line_is_valid);
static void gpiodevice_release(struct device *dev) 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); list_del(&gdev->list);
ida_free(&gpio_ida, gdev->id); ida_free(&gpio_ida, gdev->id);
@ -605,7 +605,6 @@ int gpiochip_add_data_with_key(struct gpio_chip *gc, void *data,
goto err_free_ida; goto err_free_ida;
device_initialize(&gdev->dev); device_initialize(&gdev->dev);
dev_set_drvdata(&gdev->dev, gdev);
if (gc->parent && gc->parent->driver) if (gc->parent && gc->parent->driver)
gdev->owner = gc->parent->driver->owner; gdev->owner = gc->parent->driver->owner;
else if (gc->owner) else if (gc->owner)