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Message-Id: <20190726142628.20534-1-vdronov@redhat.com>
Date: Fri, 26 Jul 2019 16:26:28 +0200
From: Vladis Dronov <vdronov@...hat.com>
To: vdronov@...hat.com, Marcel Holtmann <marcel@...tmann.org>,
Johan Hedberg <johan.hedberg@...il.com>,
linux-bluetooth@...r.kernel.org, linux-kernel@...r.kernel.org,
Suraj Sumangala <suraj@...eros.com>,
Frederic Danis <frederic.danis@...ux.intel.com>,
Loic Poulain <loic.poulain@...el.com>,
Balakrishna Godavarthi <bgodavar@...eaurora.org>,
syzkaller@...glegroups.com
Subject: [PATCH v2] Bluetooth: hci_ldisc: 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 check for the missing tty
operations the same way it is done for write().
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@...kaller.appspotmail.com
Cc: stable@...r.kernel.org # v2.6.36+
Fixes: c19483cc5e56 ("bluetooth: Fix missing NULL check")
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@...hat.com>
---
out-of-commit-message-note:
I believe, this is a good location for the check. This way we protect protocols
which does not call tiocm[gs]et() or hci_uart_set_flow_control() but may
change to call them in the future.
Also we do not need hci_uart_has_tiocm_support() helper now.
drivers/bluetooth/hci_ldisc.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/drivers/bluetooth/hci_ldisc.c b/drivers/bluetooth/hci_ldisc.c
index c84f985f348d..4a85c51d0307 100644
--- a/drivers/bluetooth/hci_ldisc.c
+++ b/drivers/bluetooth/hci_ldisc.c
@@ -459,10 +459,11 @@ static int hci_uart_tty_open(struct tty_struct *tty)
BT_DBG("tty %p", tty);
- /* Error if the tty has no write op instead of leaving an exploitable
- * hole
+ /* Error if the tty has no write or tiocm[gs]et ops instead of leaving
+ * an exploitable hole
*/
- if (tty->ops->write == NULL)
+ if (tty->ops->write == NULL || tty->ops->tiocmget == NULL ||
+ tty->ops->tiocmset == NULL)
return -EOPNOTSUPP;
hu = kzalloc(sizeof(struct hci_uart), GFP_KERNEL);
--
2.21.0
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