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Date:   Tue, 29 Jan 2019 21:39:28 -0800
From:   Myungho Jung <mhjungk@gmail.com>
To:     Marcel Holtmann <marcel@holtmann.org>,
        Johan Hedberg <johan.hedberg@gmail.com>
Cc:     linux-bluetooth@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH v2] Bluetooth: Add NULL check for tiocmget() and tiocmset()
Message-ID: <20190130053925.GA26699@myunghoj-Precision-5530>
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Sender: linux-kernel-owner@vger.kernel.org
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tiocmget() and tiocmset() operations are optional and some tty drivers
like pty miss the operations. We need NULL check to prevent from
dereference.

Signed-off-by: Myungho Jung <mhjungk@gmail.com>
---
 drivers/bluetooth/hci_ath.c   | 6 ++++++
 drivers/bluetooth/hci_ldisc.c | 4 ++++
 2 files changed, 10 insertions(+)

diff --git a/drivers/bluetooth/hci_ath.c b/drivers/bluetooth/hci_ath.c
index d568fbd94d6c..fb9f6323a911 100644
--- a/drivers/bluetooth/hci_ath.c
+++ b/drivers/bluetooth/hci_ath.c
@@ -185,8 +185,14 @@ static int ath_set_bdaddr(struct hci_dev *hdev, const bdaddr_t *bdaddr)
 
 static int ath_setup(struct hci_uart *hu)
 {
+	struct tty_struct *tty = hu->tty;
+
 	BT_DBG("hu %p", hu);
 
+	/* tty driver should support operations to set RTS */
+	if (!tty->driver->ops->tiocmget || !tty->driver->ops->tiocmset)
+		return -EOPNOTSUPP;
+
 	hu->hdev->set_bdaddr = ath_set_bdaddr;
 
 	return 0;
diff --git a/drivers/bluetooth/hci_ldisc.c b/drivers/bluetooth/hci_ldisc.c
index fbf7b4df23ab..cb31c2d8d826 100644
--- a/drivers/bluetooth/hci_ldisc.c
+++ b/drivers/bluetooth/hci_ldisc.c
@@ -314,6 +314,10 @@ 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