Re: [PATCH 5/5] USB: serial: quatech2: handle unbound ports

[Johan Hovold <johan@kernel.org>]

On Fri, Jan 17, 2020 at 02:13:56PM +0100, Greg Kroah-Hartman wrote:
> On Fri, Jan 17, 2020 at 11:53:17AM +0100, Johan Hovold wrote:
> > On Fri, Jan 17, 2020 at 11:36:39AM +0100, Greg Kroah-Hartman wrote:
> > > On Fri, Jan 17, 2020 at 10:50:26AM +0100, Johan Hovold wrote:
> > > > Check for NULL port data in the event handlers to avoid dereferencing a
> > > > NULL pointer in the unlikely case where a port device isn't bound to a
> > > > driver (e.g. after an allocation failure on port probe).
> > > > 
> > > > Fixes: f7a33e608d9a ("USB: serial: add quatech2 usb to serial driver")
> > > > Cc: stable <stable@vger.kernel.org>     # 3.5
> > > > Signed-off-by: Johan Hovold <johan@kernel.org>

> > I'll respin this last one in some way, thanks.
> 
> Nah, that's fine, this is ok as-is, thanks.

I wasn't too happy with this myself, so I reverted to my first version
of simply adding the checks the lsr/msr helper where the actual
dereference takes place.

The downside is that it's a bit disconnected from where the actual port
lookup takes place (qt2_process_read_urb()). But I thinks it's still
preferred over adding sanity checks to those event-handler stubs, which
admittedly looks quite weird.

I've applied the first four and will send a v2 of this one.

Johan