Re: [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:

quoted

Hi Alexey,

Good catch!

On Fri, Jul 13, 2018 at 11:07:57PM +0300, Alexey Khoroshilov wrote:

quoted

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 <redacted>

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