Hi Shuah, > tty_set_termios() has the following WARN_ON which can be triggered with a > syscall to invoke TIOCSETD __NR_ioctl. > > WARN_ON(tty->driver->type == TTY_DRIVER_TYPE_PTY && > tty->driver->subtype == PTY_TYPE_MASTER); > Reference: https://syzkaller.appspot.com/bug?id=2410d22f1d8e5984217329dd0884b01d99e3e48d > > Johan Hovold said: "The problemm 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." > > Fix it by by preventing setting the HCI line discipline for PTYs in > hci_uart_tty_open(). Looked into keying off of tty and ldisc ops, and > couldn't find any that would be conclusive. Checking tty as such clearly > tags the reason for rejecting the request to set ldisc. > > Reported-by: syzbot+a950165cbb86bdd023a4@xxxxxxxxxxxxxxxxxxxxxxxxx > Cc: Johan Hovold <johan@xxxxxxxxxx> > Cc: Marcel Holtmann <marcel@xxxxxxxxxxxx> > Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx> > Signed-off-by: Shuah Khan <shuah@xxxxxxxxxx> > --- > drivers/bluetooth/hci_ldisc.c | 5 +++++ > 1 file changed, 5 insertions(+) > > diff --git a/drivers/bluetooth/hci_ldisc.c b/drivers/bluetooth/hci_ldisc.c > index fbf7b4df23ab..a3d313fcc0f2 100644 > --- a/drivers/bluetooth/hci_ldisc.c > +++ b/drivers/bluetooth/hci_ldisc.c > @@ -480,6 +480,11 @@ static int hci_uart_tty_open(struct tty_struct *tty) > if (tty->ops->write == NULL) > return -EOPNOTSUPP; > > + /* don't set HCI line discipline on PTYs */ > + if (tty->driver->type == TTY_DRIVER_TYPE_PTY && > + tty->driver->subtype == PTY_TYPE_MASTER) > + return -EINVAL; > + this is turning in circles. What is wrong with checking !tty->ops->set_termios here? Regards Marcel
