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From: Greg KH <greg@kroah.com>
To: Johan Hovold <johan@kernel.org>
Cc: linux-usb@vger.kernel.org, stable <stable@vger.kernel.org>
Subject: Re: [PATCH] USB: serial: suppress driver bind attributes
Date: Thu, 16 Jan 2020 20:06:06 +0100
Message-ID: <20200116190606.GB1020857@kroah.com> (raw)
In-Reply-To: <20200116162424.GP2301@localhost>

On Thu, Jan 16, 2020 at 05:24:24PM +0100, Johan Hovold wrote:
> On Thu, Jan 16, 2020 at 05:18:29PM +0100, Greg Kroah-Hartman wrote:
> > On Thu, Jan 16, 2020 at 05:07:05PM +0100, Johan Hovold wrote:
> > > USB-serial drivers must not be unbound from their ports before the
> > > corresponding USB driver is unbound from the parent interface so
> > > suppress the bind and unbind attributes.
> > > 
> > > Unbinding a serial driver while it's port is open is a sure way to
> > > trigger a crash as any driver state is released on unbind while port
> > > hangup is handled on the parent USB interface level. Drivers for
> > > multiport devices where ports share a resource such as an interrupt
> > > endpoint also generally cannot handle individual ports going away.
> > > 
> > > Cc: stable <stable@vger.kernel.org>
> > > Signed-off-by: Johan Hovold <johan@kernel.org>
> > > ---
> > >  drivers/usb/serial/usb-serial.c | 3 +++
> > >  1 file changed, 3 insertions(+)
> > > 
> > > diff --git a/drivers/usb/serial/usb-serial.c b/drivers/usb/serial/usb-serial.c
> > > index 8f066bb55d7d..dc7a65b9ec98 100644
> > > --- a/drivers/usb/serial/usb-serial.c
> > > +++ b/drivers/usb/serial/usb-serial.c
> > > @@ -1317,6 +1317,9 @@ static int usb_serial_register(struct usb_serial_driver *driver)
> > >  		return -EINVAL;
> > >  	}
> > >  
> > > +	/* Prevent individual ports from being unbound. */
> > > +	driver->driver.suppress_bind_attrs = true;
> > 
> > We can still unbind the usb driver though, right?  If so, this is fine
> > with me.
> 
> Right, this is only about disabling individual ports, something which
> essentially no subdriver can handle while a port is open (e.g. port-data
> set to NULL while port is still open... boom).

Ok, thanks for verifying, and sorry for writing that bug in the first
place :)

Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

  reply index

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-16 16:07 Johan Hovold
2020-01-16 16:18 ` Greg KH
2020-01-16 16:24   ` Johan Hovold
2020-01-16 19:06     ` Greg KH [this message]
2020-01-17 10:13       ` Johan Hovold

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