linux-kernel - Re: [PATCH v3 2/9] usb: typec: Add retimer handle to port

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Message-ID: <Ysf3F3VvmoqCFj4P@kroah.com>
Date:   Fri, 8 Jul 2022 11:21:27 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     Sergey Shtylyov <s.shtylyov@....ru>
Cc:     Prashant Malani <pmalani@...omium.org>,
        linux-kernel@...r.kernel.org, linux-usb@...r.kernel.org,
        chrome-platform@...ts.linux.dev, bleung@...omium.org,
        heikki.krogerus@...ux.intel.com,
        Daisuke Nojiri <dnojiri@...omium.org>,
        "Dustin L. Howett" <dustin@...ett.net>,
        Guenter Roeck <groeck@...omium.org>,
        "Gustavo A. R. Silva" <gustavoars@...nel.org>,
        Kees Cook <keescook@...omium.org>,
        Sebastian Reichel <sebastian.reichel@...labora.com>,
        Tzung-Bi Shih <tzungbi@...nel.org>
Subject: Re: [PATCH v3 2/9] usb: typec: Add retimer handle to port

On Fri, Jul 08, 2022 at 11:46:44AM +0300, Sergey Shtylyov wrote:
> Hello!
> 
> On 7/8/22 1:20 AM, Prashant Malani wrote:
> 
> > Similar to mux and orientation switch, add a handle for registered
> > retimer to the port, so that it has handles to the various switches
> > connected to it.
> > 
> > Signed-off-by: Prashant Malani <pmalani@...omium.org>
> > ---
> > 
> > Changes since v2:
> > - No changes.
> > 
> > Changes since v1:
> > - Relinquish retimer reference during typec_release.
> > 
> >  drivers/usb/typec/class.c | 9 +++++++++
> >  drivers/usb/typec/class.h | 1 +
> >  2 files changed, 10 insertions(+)
> > 
> > diff --git a/drivers/usb/typec/class.c b/drivers/usb/typec/class.c
> > index 9062836bb638..f08e32d552b4 100644
> > --- a/drivers/usb/typec/class.c
> > +++ b/drivers/usb/typec/class.c
> [...]
> > @@ -2249,6 +2251,13 @@ struct typec_port *typec_register_port(struct device *parent,
> >  		return ERR_PTR(ret);
> >  	}
> >  
> > +	port->retimer = typec_retimer_get(&port->dev);
> > +	if (IS_ERR(port->retimer)) {
> > +		ret = PTR_ERR(port->retimer);
> > +		put_device(&port->dev);
> > +		return ERR_PTR(ret);
> 
>    Why convert it to and fro, and not just return port->retimer?

That would be a use-after-free as port might now be gone.

thanks,

greg k-h