On Tue, Sep 22, 2020 at 02:07:02PM +0300, M. Vefa Bicakci wrote:
> This commit resolves a minor bug in the selection/discovery of more
> specific USB device drivers for devices that are currently bound to
> generic USB device drivers.
>
> The bug is related to the way a candidate USB device driver is
> compared against the generic USB device driver. The code in
> is_dev_usb_generic_driver() assumes that the device driver in question
> is a USB device driver by calling to_usb_device_driver(dev->driver)
> to downcast; however I have observed that this assumption is not always
> true, through code instrumentation.
>
> This commit avoids the incorrect downcast altogether by comparing
> the USB device's driver (i.e., dev->driver) to the generic USB
> device driver directly. This method was suggested by Alan Stern.
>
> This bug was found while investigating Andrey Konovalov's report
> indicating usbip device driver misbehaviour with the recently merged
> generic USB device driver selection feature. The report is linked
> below.
>
> Fixes: d5643d2249 ("USB: Fix device driver race")
Nit, this should have been:
Fixes: d5643d2249b2 ("USB: Fix device driver race")
I'll go fix it up as my scripts are rejecting it as-is...
thanks,
greg k-h
