On Tue, Feb 10, 2015 at 08:39:26PM +0000, Ben Hutchings wrote: > On Mon, 2015-01-05 at 16:04 +0100, Johan Hovold wrote: > > Use tty kref to release the fake tty in usb_console_setup to avoid use > > after free if the underlying serial driver has acquired a reference. > > > > Note that using the tty destructor release_one_tty requires some more > > state to be initialised. > [...] > > --- a/drivers/usb/serial/console.c > > +++ b/drivers/usb/serial/console.c > [...] > > @@ -137,14 +139,17 @@ static int usb_console_setup(struct console *co, char > > *options) > > goto reset_open_count; > > } > > kref_init(&tty->kref); > > - tty_port_tty_set(&port->port, tty); > > tty->driver = usb_serial_tty_driver; > > tty->index = co->index; > > init_ldsem(&tty->ldisc_sem); > > + INIT_LIST_HEAD(&tty->tty_files); > > + kref_get(&tty->driver->kref); > > + tty->ops = &usb_console_fake_tty_ops; > [...] > > Do we also need: > __module_get(tty->driver->owner); > or am I missing something?
When the console setup code is running, and while the console is open, everything is pinned through a reference to the usb-serial-driver module (the tty layer also pins usb-serial core directly). We should be holding a reference to the usb-serial driver module (which in turns pins usb-serial core, which is the tty driver) for when the console isn't open as well, although that is not directly related to the fix in question. Yes, the USB console is a bit of a hack. Johan -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
