linux-kernel - Re: Inconsistency in usb_add_gadget_udc

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Message-ID: <8760do6lqt.fsf@linux.intel.com>
Date:   Wed, 16 Aug 2017 09:59:54 +0300
From:   Felipe Balbi <balbi@...nel.org>
To:     Alexey Khoroshilov <khoroshilov@...ras.ru>,
        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: Re: Inconsistency in usb_add_gadget_udc_release() interface


Hi,

Alexey Khoroshilov <khoroshilov@...ras.ru> writes:
> 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?

unfortunately, it's not :-)

Note that we don't register gadget->dev until later in the code, so
there's nothing to be ->released() that early.

-- 
balbi

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