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

[Sergey Shtylyov]

On 7/8/22 12:21 PM, Greg Kroah-Hartman 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@xxxxxxxxxxxx>
>>> ---
>>>
>>> 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.

   Ah, indeed!
   It would also ensue an explicit pointer cast...

> thanks,
> 
> greg k-h

MBR, Sergey