Commit 8a700b1f authored by Danilo Krummrich's avatar Danilo Krummrich
Browse files

platform/wmi: use generic driver_override infrastructure 

When a driver is probed through __driver_attach(), the bus' match()
callback is called without the device lock held, thus accessing the
driver_override field without a lock, which can cause a UAF.

Fix this by using the driver-core driver_override infrastructure taking
care of proper locking internally.

Note that calling match() from __driver_attach() without the device lock
held is intentional. [1]

Link: https://lore.kernel.org/driver-core/DGRGTIRHA62X.3RY09D9SOK77P@kernel.org/

 [1]
Reported-by: default avatarGui-Dong Han <hanguidong02@gmail.com>
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=220789


Fixes: 12046f8c ("platform/x86: wmi: Add driver_override support")
Reviewed-by: default avatarArmin Wolf <W_Armin@gmx.de>
Acked-by: default avatarIlpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://patch.msgid.link/20260324005919.2408620-7-dakr@kernel.org


Signed-off-by: default avatarDanilo Krummrich <dakr@kernel.org>
parent 10a4206a

drivers/platform/wmi/core.c

+5 −31
Original line number Diff line number Diff line
@@ -842,39 +842,11 @@ static ssize_t expensive_show(struct device *dev, 
}

static DEVICE_ATTR_RO(expensive);



static ssize_t driver_override_show(struct device *dev, struct device_attribute *attr,

				    char *buf)

{

	struct wmi_device *wdev = to_wmi_device(dev);

	ssize_t ret;



	device_lock(dev);

	ret = sysfs_emit(buf, "%s\n", wdev->driver_override);

	device_unlock(dev);



	return ret;

}



static ssize_t driver_override_store(struct device *dev, struct device_attribute *attr,

				     const char *buf, size_t count)

{

	struct wmi_device *wdev = to_wmi_device(dev);

	int ret;



	ret = driver_set_override(dev, &wdev->driver_override, buf, count);

	if (ret < 0)

		return ret;



	return count;

}

static DEVICE_ATTR_RW(driver_override);



static struct attribute *wmi_attrs[] = {

	&dev_attr_modalias.attr,

	&dev_attr_guid.attr,

	&dev_attr_instance_count.attr,

	&dev_attr_expensive.attr,

	&dev_attr_driver_override.attr,

	NULL

};

ATTRIBUTE_GROUPS(wmi);
@@ -943,7 +915,6 @@ static void wmi_dev_release(struct device *dev) 
{

	struct wmi_block *wblock = dev_to_wblock(dev);



	kfree(wblock->dev.driver_override);

	kfree(wblock);

}
@@ -952,10 +923,12 @@ static int wmi_dev_match(struct device *dev, const struct device_driver *driver) 
	const struct wmi_driver *wmi_driver = to_wmi_driver(driver);

	struct wmi_block *wblock = dev_to_wblock(dev);

	const struct wmi_device_id *id = wmi_driver->id_table;

	int ret;



	/* When driver_override is set, only bind to the matching driver */

	if (wblock->dev.driver_override)

		return !strcmp(wblock->dev.driver_override, driver->name);

	ret = device_match_driver_override(dev, driver);

	if (ret >= 0)

		return ret;



	if (id == NULL)

		return 0;
@@ -1076,6 +1049,7 @@ static struct class wmi_bus_class = { 
static const struct bus_type wmi_bus_type = {

	.name = "wmi",

	.dev_groups = wmi_groups,

	.driver_override = true,

	.match = wmi_dev_match,

	.uevent = wmi_dev_uevent,

	.probe = wmi_dev_probe,

include/linux/wmi.h

+0 −4
Original line number Diff line number Diff line
@@ -18,16 +18,12 @@ 
 * struct wmi_device - WMI device structure

 * @dev: Device associated with this WMI device

 * @setable: True for devices implementing the Set Control Method

 * @driver_override: Driver name to force a match; do not set directly,

 *		     because core frees it; use driver_set_override() to

 *		     set or clear it.

 *

 * This represents WMI devices discovered by the WMI driver core.

 */

struct wmi_device {

	struct device dev;

	bool setable;

	const char *driver_override;

};



/**