Bluetooth: hci_uart: check for missing tty operations

This change “Bluetooth: hci_uart: check for missing tty operations” in Linux kernel is authored by Vladis Dronov <vdronov [at]> on Tue Jul 30 11:33:45 2019 +0200.

Bluetooth: hci_uart: check for missing tty operations

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 helper function and a check
for the missing tty operations in the protocols code.

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

Cc: # v2.6.36+
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 <>
Signed-off-by: Marcel Holtmann <>
Reviewed-by: Yu-Chen, Cho <>
Tested-by: Yu-Chen, Cho <>
Signed-off-by: Linus Torvalds <>

This Linux change may have been applied to various maintained Linux releases and you can find Linux releases including commit b36a155.

There are 29 lines of Linux source code added/deleted in this change. Code changes to Linux kernel are as follows.

 drivers/bluetooth/hci_ath.c   |  3 +++
 drivers/bluetooth/hci_bcm.c   |  3 +++
 drivers/bluetooth/hci_intel.c |  3 +++
 drivers/bluetooth/hci_ldisc.c | 13 +++++++++++++
 drivers/bluetooth/hci_mrvl.c  |  3 +++
 drivers/bluetooth/hci_qca.c   |  3 +++
 drivers/bluetooth/hci_uart.h  |  1 +
 7 files changed, 29 insertions(+)

diff --git a/drivers/bluetooth/hci_ath.c b/drivers/bluetooth/hci_ath.c
index a55be20..dbfe346 100644
--- a/drivers/bluetooth/hci_ath.c
+++ b/drivers/bluetooth/hci_ath.c
@@ -98,6 +98,9 @@ static int ath_open(struct hci_uart *hu)
 	BT_DBG("hu %p", hu);
+	if (!hci_uart_has_flow_control(hu))
+		return -EOPNOTSUPP;
 	ath = kzalloc(sizeof(*ath), GFP_KERNEL);
 	if (!ath)
 		return -ENOMEM;
diff --git a/drivers/bluetooth/hci_bcm.c b/drivers/bluetooth/hci_bcm.c
index 8905ad2..ae2624f 100644
--- a/drivers/bluetooth/hci_bcm.c
+++ b/drivers/bluetooth/hci_bcm.c
@@ -406,6 +406,9 @@ static int bcm_open(struct hci_uart *hu)
 	bt_dev_dbg(hu->hdev, "hu %p", hu);
+	if (!hci_uart_has_flow_control(hu))
+		return -EOPNOTSUPP;
 	bcm = kzalloc(sizeof(*bcm), GFP_KERNEL);
 	if (!bcm)
 		return -ENOMEM;
diff --git a/drivers/bluetooth/hci_intel.c b/drivers/bluetooth/hci_intel.c
index 207bae5..31f2515 100644
--- a/drivers/bluetooth/hci_intel.c
+++ b/drivers/bluetooth/hci_intel.c
@@ -391,6 +391,9 @@ static int intel_open(struct hci_uart *hu)
 	BT_DBG("hu %p", hu);
+	if (!hci_uart_has_flow_control(hu))
+		return -EOPNOTSUPP;
 	intel = kzalloc(sizeof(*intel), GFP_KERNEL);
 	if (!intel)
 		return -ENOMEM;
diff --git a/drivers/bluetooth/hci_ldisc.c b/drivers/bluetooth/hci_ldisc.c
index 8950e07..85a30fb 100644
--- a/drivers/bluetooth/hci_ldisc.c
+++ b/drivers/bluetooth/hci_ldisc.c
@@ -292,6 +292,19 @@ static int hci_uart_send_frame(struct hci_dev *hdev, struct sk_buff *skb)
 	return 0;
+/* Check the underlying device or tty has flow control support */
+bool hci_uart_has_flow_control(struct hci_uart *hu)
+	/* serdev nodes check if the needed operations are present */
+	if (hu->serdev)
+		return true;
+	if (hu->tty->driver->ops->tiocmget && hu->tty->driver->ops->tiocmset)
+		return true;
+	return false;
 /* Flow control or un-flow control the device */
 void hci_uart_set_flow_control(struct hci_uart *hu, bool enable)
diff --git a/drivers/bluetooth/hci_mrvl.c b/drivers/bluetooth/hci_mrvl.c
index f98e5cc..fbc3f7c 100644
--- a/drivers/bluetooth/hci_mrvl.c
+++ b/drivers/bluetooth/hci_mrvl.c
@@ -59,6 +59,9 @@ static int mrvl_open(struct hci_uart *hu)
 	BT_DBG("hu %p", hu);
+	if (!hci_uart_has_flow_control(hu))
+		return -EOPNOTSUPP;
 	mrvl = kzalloc(sizeof(*mrvl), GFP_KERNEL);
 	if (!mrvl)
 		return -ENOMEM;
diff --git a/drivers/bluetooth/hci_qca.c b/drivers/bluetooth/hci_qca.c
index 9a5c9c1..82a0a36 100644
--- a/drivers/bluetooth/hci_qca.c
+++ b/drivers/bluetooth/hci_qca.c
@@ -473,6 +473,9 @@ static int qca_open(struct hci_uart *hu)
 	BT_DBG("hu %p qca_open", hu);
+	if (!hci_uart_has_flow_control(hu))
+		return -EOPNOTSUPP;
 	qca = kzalloc(sizeof(struct qca_data), GFP_KERNEL);
 	if (!qca)
 		return -ENOMEM;
diff --git a/drivers/bluetooth/hci_uart.h b/drivers/bluetooth/hci_uart.h
index f11af39..6ab6311 100644
--- a/drivers/bluetooth/hci_uart.h
+++ b/drivers/bluetooth/hci_uart.h
@@ -104,6 +104,7 @@ struct hci_uart {
 int hci_uart_init_ready(struct hci_uart *hu);
 void hci_uart_init_work(struct work_struct *work);
 void hci_uart_set_baudrate(struct hci_uart *hu, unsigned int speed);
+bool hci_uart_has_flow_control(struct hci_uart *hu);
 void hci_uart_set_flow_control(struct hci_uart *hu, bool enable);
 void hci_uart_set_speeds(struct hci_uart *hu, unsigned int init_speed,
 			 unsigned int oper_speed);

The commit for this change in Linux stable tree is b36a155 (patch).

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