Recently, our syzbot test reported NULL pointer dereference in device_del() by injecting memory allocation fail in device_add().
For now, callers of device_add(), such as add_disk(), may ignore device_add()'s fail and go on working. In unregister path, it will call device_del() from del_gendisk(). That can cause various NULL pointer dereference, including dev->p is NULL in kill_device(), 'name' is NULL in sysfs_remove_link(), kobj->sd is 'NULL' when call dpm_sysfs_remove(), and so on. To avoid these kernel panic, we call device_del() only when device_add() is success. Signed-off-by: Yufen Yu <[email protected]> --- drivers/base/core.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/base/core.c b/drivers/base/core.c index f29839382f81..a10ec5dbc577 100644 --- a/drivers/base/core.c +++ b/drivers/base/core.c @@ -3380,6 +3380,9 @@ void device_del(struct device *dev) struct class_interface *class_intf; unsigned int noio_flag; + if (!dev->p) + return; + device_lock(dev); kill_device(dev); device_unlock(dev); -- 2.25.4
