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SubjectRe: [PATCH] Input: pxrc - fix leak of usb_device
On Sat, Jul 14, 2018 at 08:51:09AM +0000, Dmitry Torokhov wrote:
> On Sat, Jul 14, 2018 at 10:09:20AM +0200, Marcus Folkesson wrote:
> > Hi Alexey,
> >
> > Good catch!
> >
> > On Fri, Jul 13, 2018 at 11:07:57PM +0300, Alexey Khoroshilov wrote:
> > > pxrc_probe() calls usb_get_dev(), but there is no usb_put_dev()
> > > anywhere in the driver.
> > >
> > > The patch adds one to error handling code and to pxrc_disconnect().
> > >
> > > Found by Linux Driver Verification project (linuxtesting.org).
> > >
> > > Signed-off-by: Alexey Khoroshilov <khoroshilov@ispras.ru>
> >
> > Reviewed-by: Marcus Folkesson <marcus.folkesson@gmail.com>
>
> Hmm, the biggest question however if we need to "take" the device, as I
> do not think interface can outlive the device, and whether we actually
> need to store it in pxrc, as we only need it during set up, as far as I
> can see.

Yep, the device is only used during setup.
I interpret the comments for usb_get_dev() as you should take a
reference count on the device even if you only use the interface, but I
could be wrong.

From usb_get_dev()::

* usb_get_dev - increments the reference count of the usb device structure
* @dev: the device being referenced
*
* Each live reference to a device should be refcounted.
*
* Drivers for USB interfaces should normally record such references in
* their probe() methods, when they bind to an interface, and release
* them by calling usb_put_dev(), in their disconnect() methods.

I can fix the driver to not take the device if that is what we want.
If not Alexey want to fix it of course, it is his catch :-)

>
> Thanks.
>
> --
> Dmitry

Best regards
Marcus Folkesson
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