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

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Date:   Sun, 27 Jan 2019 22:59:13 -0800
From:   Myungho Jung <mhjungk@...il.com>
To:     Marcel Holtmann <marcel@...tmann.org>,
        Johan Hedberg <johan.hedberg@...il.com>
Cc:     linux-bluetooth@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] Bluetooth: Add NULL check for tiocmget() and tiocmset()

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+a950165cbb86bdd023a4@...kaller.appspotmail.com
Signed-off-by: Myungho Jung <mhjungk@...il.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