linux-kernel - [PATCH v2] Bluetooth: Add NULL check for tiocmget() and tiocmset()

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Date:   Tue, 29 Jan 2019 21:39:28 -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 v2] 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 to prevent from
dereference.

Signed-off-by: Myungho Jung <mhjungk@...il.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