linux-kernel - Inconsistency in usb_add_gadget_udc

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Message-Id: <1502833167-19354-1-git-send-email-khoroshilov@ispras.ru>
Date:   Wed, 16 Aug 2017 00:39:27 +0300
From:   Alexey Khoroshilov <khoroshilov@...ras.ru>
To:     Felipe Balbi <balbi@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Alexey Khoroshilov <khoroshilov@...ras.ru>,
        Krzysztof Opasiak <k.opasiak@...sung.com>,
        Anton Vasilyev <vasilyev@...ras.ru>, linux-usb@...r.kernel.org,
        linux-kernel@...r.kernel.org, ldv-project@...uxtesting.org
Subject: Inconsistency in usb_add_gadget_udc_release() interface

Hello,

usb_add_gadget_udc_release() gets release() argument that allows to
release user resources.

As far as I can see, the release() is called on error paths 
of usb_add_gadget_udc_release() as a result of
put_device(&gadget->dev);
except for the only path going via err1.

As a result a caller of the usb_add_gadget_udc_release() have no chance
to know if the release() was invoked or not.

It may lead to memory leaks (drivers/usb/gadget/udc/snps_udc_core.c)
or to double free (drivers/usb/gadget/udc/fsl_udc_core.c).

Is my reading correct? If so, should we always call release() on error paths?

--
Alexey Khoroshilov
Linux Verification Center, ISPRAS
web: http://linuxtesting.org