linux-kernel - Re: [PATCH] media: usb: fix memory leak in stk_camera

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Message-ID: <20210902141745.GD2129@kadam>
Date:   Thu, 2 Sep 2021 17:17:45 +0300
From:   Dan Carpenter <dan.carpenter@...cle.com>
To:     Dongliang Mu <mudongliangabcd@...il.com>
Cc:     Mauro Carvalho Chehab <mchehab@...nel.org>,
        linux-media@...r.kernel.org,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Greg KH <gregkh@...uxfoundation.org>
Subject: Re: [PATCH] media: usb: fix memory leak in stk_camera_probe

On Thu, Sep 02, 2021 at 06:23:36PM +0800, Dongliang Mu wrote:
> On Fri, Jul 23, 2021 at 6:11 PM Dongliang Mu <mudongliangabcd@...il.com> wrote:
> >
> > On Wed, Jul 14, 2021 at 11:23 AM Dongliang Mu <mudongliangabcd@...il.com> wrote:
> > >
> > > stk_camera_probe mistakenly execute usb_get_intf and increase the
> > > refcount of interface->dev.
> > >
> > > Fix this by removing the execution of usb_get_intf.
> >
> > Any idea about this patch?
> 
> +cc Dan Carpenter, gregkh
> 
> There is no reply in this thread in one month. Can someone give some
> feedback on this patch?
> 
> >
> > >
> > > Reported-by: Dongliang Mu <mudongliangabcd@...il.com>
> > > Fixes: 0aa77f6c2954 ("[media] move the remaining USB drivers to drivers/media/usb")
> > > Signed-off-by: Dongliang Mu <mudongliangabcd@...il.com>
> > > ---
> > >  drivers/media/usb/stkwebcam/stk-webcam.c | 1 -
> > >  1 file changed, 1 deletion(-)
> > >
> > > diff --git a/drivers/media/usb/stkwebcam/stk-webcam.c b/drivers/media/usb/stkwebcam/stk-webcam.c
> > > index a45d464427c4..5bd8e85b9452 100644
> > > --- a/drivers/media/usb/stkwebcam/stk-webcam.c
> > > +++ b/drivers/media/usb/stkwebcam/stk-webcam.c
> > > @@ -1311,7 +1311,6 @@ static int stk_camera_probe(struct usb_interface *interface,
> > >
> > >         dev->udev = udev;
> > >         dev->interface = interface;
> > > -       usb_get_intf(interface);


The patch is wrong.  We're storing a reference to "interface".

	dev->interface = interface;

So we need to boost the refcount of interface.  Pavel Skripkin was on
the right patch but you need to add a:

	usb_put_intf(interface);

to the stk_camera_disconnect() function as you sort of mentioned.
That's the correct fix.

regards,
dan carpenter