On 2/3/19 10:39 PM, Marcel Holtmann wrote:
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 "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." Fix it by by preventing setting the HCI line discipline for PTYs in hci_uart_tty_open(). Reported-by: [email protected] Cc: Johan Hovold <[email protected]> Cc: Marcel Holtmann <[email protected]> Cc: Al Viro <[email protected]> Signed-off-by: Shuah Khan <[email protected]> --- drivers/bluetooth/hci_ldisc.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/bluetooth/hci_ldisc.c b/drivers/bluetooth/hci_ldisc.c index fbf7b4df23ab..c8faa4759cb7 100644 --- a/drivers/bluetooth/hci_ldisc.c +++ b/drivers/bluetooth/hci_ldisc.c @@ -475,9 +475,9 @@ static int hci_uart_tty_open(struct tty_struct *tty) BT_DBG("tty %p", tty); /* Error if the tty has no write op instead of leaving an exploitable - * hole + * hole. In addition check if setting HCI line discipline is allowed. */this comment is wrong. The result of setting the HCI line discipline is a call into hci_uart_tty_open. You have to check ops->write and ops->set_termios since both are required. That is it.
I will fix the comment.
- if (tty->ops->write == NULL) + if (tty->ops->write == NULL || tty->ops->set_termios == NULL) return -EOPNOTSUPP;And while at it, change this to (!tty->ops->write).
Okay. I will fix both. thanks, -- Shuah
