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/[email protected]/ [1] Reported-by: Gui-Dong Han <[email protected]> Closes: https://bugzilla.kernel.org/show_bug.cgi?id=220789 Fixes: 12046f8c77e0 ("platform/x86: wmi: Add driver_override support") Signed-off-by: Danilo Krummrich <[email protected]> --- drivers/platform/wmi/core.c | 36 +++++------------------------------- include/linux/wmi.h | 4 ---- 2 files changed, 5 insertions(+), 35 deletions(-) diff --git a/drivers/platform/wmi/core.c b/drivers/platform/wmi/core.c index b8e6b9a421c6..750e3619724e 100644 --- a/drivers/platform/wmi/core.c +++ b/drivers/platform/wmi/core.c @@ -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, diff --git a/include/linux/wmi.h b/include/linux/wmi.h index 75cb0c7cfe57..14fb644e1701 100644 --- a/include/linux/wmi.h +++ b/include/linux/wmi.h @@ -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; }; /** -- 2.53.0
