[PATCH] Bluetooth: Add NULL check for tiocmget() and tiocmset()

[Myungho Jung]

tiocmget() and tiocmset() operations are optional and some tty drivers
like pty miss the operations. We need NULL check before referencing
them.

Reported-by: syzbot+a950165cbb86bdd02...@syzkaller.appspotmail.com
Signed-off-by: Myungho Jung <mhju...@gmail.com>
---
 drivers/bluetooth/hci_ath.c   | 13 ++++++++-----
 drivers/bluetooth/hci_ldisc.c |  5 +++++
 2 files changed, 13 insertions(+), 5 deletions(-)

diff --git a/drivers/bluetooth/hci_ath.c b/drivers/bluetooth/hci_ath.c
index d568fbd94d6c..076700a1e9a8 100644
--- a/drivers/bluetooth/hci_ath.c
+++ b/drivers/bluetooth/hci_ath.c
@@ -94,11 +94,14 @@ static void ath_hci_uart_work(struct work_struct *work)
        hu = ath->hu;
        tty = hu->tty;
 
-       /* verify and wake up controller */
-       if (ath->cur_sleep) {
-               status = ath_wakeup_ar3k(tty);
-               if (!(status & TIOCM_CTS))
-                       return;
+       /* tiocmget() and tiocmset() operations are optional */
+       if (tty->driver->ops->tiocmget && tty->driver->ops->tiocmset) {
+               /* verify and wake up controller */
+               if (ath->cur_sleep) {
+                       status = ath_wakeup_ar3k(tty);
+                       if (!(status & TIOCM_CTS))
+                               return;
+               }
        }
 
        /* Ready to send Data */
diff --git a/drivers/bluetooth/hci_ldisc.c b/drivers/bluetooth/hci_ldisc.c
index fbf7b4df23ab..9f88a8563cf6 100644
--- a/drivers/bluetooth/hci_ldisc.c
+++ b/drivers/bluetooth/hci_ldisc.c
@@ -314,6 +314,11 @@ void hci_uart_set_flow_control(struct hci_uart *hu, bool 
enable)
                return;
        }
 
+       /* tiocmget() and tiocmset() operations are optional */
+       if (!tty->driver->ops->tiocmget || !tty->driver->ops->tiocmset) {
+               return;
+       }
+
        if (enable) {
                /* Disable hardware flow control */
                ktermios = tty->termios;
-- 
2.17.1