Re: [PATCH v2] tty: Fix WARNING in tty_set_termios()

[shuah]

On 2/1/19 2:28 AM, Johan Hovold wrote:
> On Thu, Jan 31, 2019 at 04:23:59PM -0700, Shuah Khan wrote:
> > tty_set_termios() has the following WARN_ON which can be triggered with a
> > syscall to invoke TIOCSETD __NR_ioctl.
>
> That's the only way to set the hci line discipline. And it's the
> consequent ioctl that sets the uart protocol that triggers the warning,
> but only if the tty is a pty master, as I mentioned before.
>
> > WARN_ON(tty->driver->type == TTY_DRIVER_TYPE_PTY &&
> >                  tty->driver->subtype == PTY_TYPE_MASTER);
> > Reference: https://syzkaller.appspot.com/bug?id=2410d22f1d8e5984217329dd0884b01d99e3e48d
> >
> > The problem started with commit 7721383f4199 ("Bluetooth: hci_uart: Support
> > operational speed during setup") which introduced a new way for how
> > tty_set_termios() could end up being called for a master pty.
>
> Please always include reviewers on CC, and especially if you end up
> citing them directly as you do here. Perhaps add quotation marks or at
> least a reference to the discussion where this solution was suggested.

Thanks for the feedback. I am folding in your and Marcel's input in my
v3.

thanks,
-- Shuah