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: 539fec78edb4 ("vdpa: add driver_override support") Signed-off-by: Danilo Krummrich <[email protected]> --- drivers/vdpa/vdpa.c | 48 +++++--------------------------------------- include/linux/vdpa.h | 4 ---- 2 files changed, 5 insertions(+), 47 deletions(-) diff --git a/drivers/vdpa/vdpa.c b/drivers/vdpa/vdpa.c index 34874beb0152..caf0ee5d6856 100644 --- a/drivers/vdpa/vdpa.c +++ b/drivers/vdpa/vdpa.c @@ -67,57 +67,20 @@ static void vdpa_dev_remove(struct device *d) static int vdpa_dev_match(struct device *dev, const struct device_driver *drv) { - struct vdpa_device *vdev = dev_to_vdpa(dev); + int ret; /* Check override first, and if set, only use the named driver */ - if (vdev->driver_override) - return strcmp(vdev->driver_override, drv->name) == 0; + ret = device_match_driver_override(dev, drv); + if (ret >= 0) + return ret; /* Currently devices must be supported by all vDPA bus drivers */ return 1; } -static ssize_t driver_override_store(struct device *dev, - struct device_attribute *attr, - const char *buf, size_t count) -{ - struct vdpa_device *vdev = dev_to_vdpa(dev); - int ret; - - ret = driver_set_override(dev, &vdev->driver_override, buf, count); - if (ret) - return ret; - - return count; -} - -static ssize_t driver_override_show(struct device *dev, - struct device_attribute *attr, char *buf) -{ - struct vdpa_device *vdev = dev_to_vdpa(dev); - ssize_t len; - - device_lock(dev); - len = sysfs_emit(buf, "%s\n", vdev->driver_override); - device_unlock(dev); - - return len; -} -static DEVICE_ATTR_RW(driver_override); - -static struct attribute *vdpa_dev_attrs[] = { - &dev_attr_driver_override.attr, - NULL, -}; - -static const struct attribute_group vdpa_dev_group = { - .attrs = vdpa_dev_attrs, -}; -__ATTRIBUTE_GROUPS(vdpa_dev); - static const struct bus_type vdpa_bus = { .name = "vdpa", - .dev_groups = vdpa_dev_groups, + .driver_override = true, .match = vdpa_dev_match, .probe = vdpa_dev_probe, .remove = vdpa_dev_remove, @@ -132,7 +95,6 @@ static void vdpa_release_dev(struct device *d) ops->free(vdev); ida_free(&vdpa_index_ida, vdev->index); - kfree(vdev->driver_override); kfree(vdev); } diff --git a/include/linux/vdpa.h b/include/linux/vdpa.h index 2bfe3baa63f4..782c42d25db1 100644 --- a/include/linux/vdpa.h +++ b/include/linux/vdpa.h @@ -72,9 +72,6 @@ struct vdpa_mgmt_dev; * struct vdpa_device - representation of a vDPA device * @dev: underlying device * @vmap: the metadata passed to upper layer to be used for mapping - * @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. * @config: the configuration ops for this device. * @map: the map ops for this device * @cf_lock: Protects get and set access to configuration layout. @@ -90,7 +87,6 @@ struct vdpa_mgmt_dev; struct vdpa_device { struct device dev; union virtio_map vmap; - const char *driver_override; const struct vdpa_config_ops *config; const struct virtio_map_ops *map; struct rw_semaphore cf_lock; /* Protects get/set config */ -- 2.53.0
