[Xenial][SRU][CVE-2019-10207][PATCH 2/2] Bluetooth: hci_uart: check for missing tty operations

[Connor Kuehl]

From: Vladis Dronov <vdronov at redhat.com>

CVE-2019-10207

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
protocols.

Link: https://syzkaller.appspot.com/bug?id=1b42faa2848963564a5b1b7f8c837ea7b55ffa50
Reported-by: syzbot+79337b501d6aa974d0f6 at syzkaller.appspotmail.com
Cc: stable at vger.kernel.org # 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 <vdronov at redhat.com>
Signed-off-by: Marcel Holtmann <marcel at holtmann.org>
Reviewed-by: Yu-Chen, Cho <acho at suse.com>
Tested-by: Yu-Chen, Cho <acho at suse.com>
Signed-off-by: Linus Torvalds <torvalds at linux-foundation.org>
(backported from commit b36a1552d7319bbfd5cf7f08726c23c5c66d4f73)
[ Connor Kuehl: drivers/bluetooth/hci_mrvl.c does not exist in Xenial,
  so that hunk was dropped. The qca_open() function had a very minor
  merge conflict but that's just because the kzalloc invocation used
  GFP_KERNEL in the patch but Xenial uses GFP_ATOMIC. ]
Signed-off-by: Connor Kuehl <connor.kuehl at canonical.com>
---
 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_qca.c   |  3 +++
 drivers/bluetooth/hci_uart.h  |  1 +
 6 files changed, 26 insertions(+)

diff --git a/drivers/bluetooth/hci_ath.c b/drivers/bluetooth/hci_ath.c
index d776dfd51478..16f2131687e5 100644
--- a/drivers/bluetooth/hci_ath.c
+++ b/drivers/bluetooth/hci_ath.c
@@ -101,6 +101,9 @@ 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 f9b569ef3dd7..20a1b4d1fd09 100644
--- a/drivers/bluetooth/hci_bcm.c
+++ b/drivers/bluetooth/hci_bcm.c
@@ -279,6 +279,9 @@ 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 f40a86960fde..772c91d843ff 100644
--- a/drivers/bluetooth/hci_intel.c
+++ b/drivers/bluetooth/hci_intel.c
@@ -407,6 +407,9 @@ 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 96bcec5598c2..8e4362361769 100644
--- a/drivers/bluetooth/hci_ldisc.c
+++ b/drivers/bluetooth/hci_ldisc.c
@@ -257,6 +257,19 @@ 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_qca.c b/drivers/bluetooth/hci_qca.c
index ecfb9ed2cff6..6b5b9ae6e809 100644
--- a/drivers/bluetooth/hci_qca.c
+++ b/drivers/bluetooth/hci_qca.c
@@ -390,6 +390,9 @@ 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_ATOMIC);
 	if (!qca)
 		return -ENOMEM;
diff --git a/drivers/bluetooth/hci_uart.h b/drivers/bluetooth/hci_uart.h
index 168aaaa2e58c..0f4bd63b94ee 100644
--- a/drivers/bluetooth/hci_uart.h
+++ b/drivers/bluetooth/hci_uart.h
@@ -109,6 +109,7 @@ int hci_uart_tx_wakeup(struct hci_uart *hu);
 int hci_uart_init_ready(struct hci_uart *hu);
 void hci_uart_init_tty(struct hci_uart *hu);
 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);
-- 
2.20.1