Alan Sternstern@rowland.harvard.edu wrote:
Ma Ke make_ruc2021@163.com writes:
When device_add(&udev->dev) failed, calling put_device() to explicitly release udev->dev. And the routine which calls usb_new_device() does not call put_device() when an error occurs.
That is wrong.
usb_new_device() is called by hub_port_connect(). The code does:
status = usb_new_device(udev); ... if (status) goto loop_disable; ...loop_disable: hub_port_disable(hub, port1, 1); loop: usb_ep0_reinit(udev); release_devnum(udev); hub_free_dev(udev); if (retry_locked) { mutex_unlock(hcd->address0_mutex); usb_unlock_port(port_dev); } usb_put_dev(udev);
And usb_put_dev() is defined in usb.c as:
void usb_put_dev(struct usb_device *dev) { if (dev) put_device(&dev->dev); }
So you see, if usb_new_device() returns a nonzero value then put_device() _is_ called.
As comment of device_add() says, 'if device_add() succeeds, you should call device_del() when you want to get rid of it. If device_add() has not succeeded, use only put_device() to drop the reference count'.
You are correct that if device_add() succeeds and a later call fails, then usb_new_device() does not properly call device_del(). Please rewrite your patch to fix only that problem.
Alan Stern
Thank you for guiding me on the vulnerability I submitted. I will resubmit the patch based on your guidance and suggestions. -- Regards,
Ma Ke