Hi Vladis, > Certain ttys operations (pty_unix98_ops) lack tiocmget() and tiocmset() > functions which are called by the certain HCI UART protocols (hci_ath, > hci_bcm, hci_intel, hci_mrvl, hci_qca) via hci_uart_set_flow_control() > or directly. This leads to an execution at NULL and can be triggered by > an unprivileged user. Fix this by adding a check for the missing tty > operations the same way it is done for write(). > > This fixes CVE-2019-10207. The Fixes: lines list commits where calls to > tiocm[gs]et() or hci_uart_set_flow_control() were added to the HCI UART > protocols. > > Link: https://syzkaller.appspot.com/bug?id=1b42faa2848963564a5b1b7f8c837ea7b55ffa50 > Reported-by: syzbot+79337b501d6aa974d0f6@xxxxxxxxxxxxxxxxxxxxxxxxx > Cc: stable@xxxxxxxxxxxxxxx # v2.6.36+ > Fixes: c19483cc5e56 ("bluetooth: Fix missing NULL check") > Fixes: b3190df62861 ("Bluetooth: Support for Atheros AR300x serial chip") > Fixes: 118612fb9165 ("Bluetooth: hci_bcm: Add suspend/resume PM functions") > Fixes: ff2895592f0f ("Bluetooth: hci_intel: Add Intel baudrate configuration support") > Fixes: 162f812f23ba ("Bluetooth: hci_uart: Add Marvell support") > Fixes: fa9ad876b8e0 ("Bluetooth: hci_qca: Add support for Qualcomm Bluetooth chip wcn3990") > Signed-off-by: Vladis Dronov <vdronov@xxxxxxxxxx> > --- > > out-of-commit-message-note: > > I believe, this is a good location for the check. This way we protect protocols > which does not call tiocm[gs]et() or hci_uart_set_flow_control() but may > change to call them in the future. > > Also we do not need hci_uart_has_tiocm_support() helper now. > > drivers/bluetooth/hci_ldisc.c | 7 ++++--- > 1 file changed, 4 insertions(+), 3 deletions(-) > > diff --git a/drivers/bluetooth/hci_ldisc.c b/drivers/bluetooth/hci_ldisc.c > index c84f985f348d..4a85c51d0307 100644 > --- a/drivers/bluetooth/hci_ldisc.c > +++ b/drivers/bluetooth/hci_ldisc.c > @@ -459,10 +459,11 @@ 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 > + /* Error if the tty has no write or tiocm[gs]et ops instead of leaving > + * an exploitable hole > */ > - if (tty->ops->write == NULL) > + if (tty->ops->write == NULL || tty->ops->tiocmget == NULL || > + tty->ops->tiocmset == NULL) > return -EOPNOTSUPP; this means that you can not run hci_h4.c on any TTY anymore. For all the vendor specific ones, I agree, but H:4 is a Bluetooth SIG defined standard one that we might want to allow on any kind of TTY since it doesn’t really mandate anything. So I would prefer if we go with a hci_uart_has_tiocm_support helper for now. Regards Marcel
