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; hu = kzalloc(sizeof(struct hci_uart), GFP_KERNEL); -- 2.21.0
