linux-kernel - [PATCH 048/102] USB: quatech2: fix use-after-free in TIOCMIWAIT

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Message-Id: <1365414657-29191-49-git-send-email-luis.henriques@canonical.com>
Date:	Mon,  8 Apr 2013 10:50:03 +0100
From:	Luis Henriques <luis.henriques@...onical.com>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	kernel-team@...ts.ubuntu.com
Cc:	Johan Hovold <jhovold@...il.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Luis Henriques <luis.henriques@...onical.com>
Subject: [PATCH 048/102] USB: quatech2: fix use-after-free in TIOCMIWAIT

3.5.7.10 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Johan Hovold <jhovold@...il.com>

commit 69f87f40d2b98e8b4ab82a121fd2bd584690b887 upstream.

Use the port wait queue and make sure to check the serial disconnected
flag before accessing private port data after waking up.

This is is needed as the private port data (including the wait queue
itself) can be gone when waking up after a disconnect.

Signed-off-by: Johan Hovold <jhovold@...il.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
[ luis: backported to 3.5; adjust context ]
Signed-off-by: Luis Henriques <luis.henriques@...onical.com>
---
 drivers/usb/serial/quatech2.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/drivers/usb/serial/quatech2.c b/drivers/usb/serial/quatech2.c
index e1065f8..1c2c0ba 100644
--- a/drivers/usb/serial/quatech2.c
+++ b/drivers/usb/serial/quatech2.c
@@ -132,7 +132,6 @@ struct qt2_port_private {
 	u8          shadowLSR;
 	u8          shadowMSR;
 
-	wait_queue_head_t   delta_msr_wait; /* Used for TIOCMIWAIT */
 	struct async_icount icount;
 
 	struct usb_serial_port *port;
@@ -528,8 +527,9 @@ static int wait_modem_info(struct usb_serial_port *port, unsigned int arg)
 	spin_unlock_irqrestore(&priv->lock, flags);
 
 	while (1) {
-		wait_event_interruptible(priv->delta_msr_wait,
-					 ((priv->icount.rng != prev.rng) ||
+		wait_event_interruptible(port->delta_msr_wait,
+					 (port->serial->disconnected ||
+					  (priv->icount.rng != prev.rng) ||
 					  (priv->icount.dsr != prev.dsr) ||
 					  (priv->icount.dcd != prev.dcd) ||
 					  (priv->icount.cts != prev.cts)));
@@ -537,6 +537,9 @@ static int wait_modem_info(struct usb_serial_port *port, unsigned int arg)
 		if (signal_pending(current))
 			return -ERESTARTSYS;
 
+		if (port->serial->disconnected)
+			return -EIO;
+
 		spin_lock_irqsave(&priv->lock, flags);
 		cur = priv->icount;
 		spin_unlock_irqrestore(&priv->lock, flags);
@@ -881,7 +884,6 @@ static int qt2_attach(struct usb_serial *serial)
 
 		spin_lock_init(&port_priv->lock);
 		spin_lock_init(&port_priv->urb_lock);
-		init_waitqueue_head(&port_priv->delta_msr_wait);
 
 		port_priv->port = serial->port[pcount];
 
@@ -1015,7 +1017,7 @@ static void qt2_update_msr(struct usb_serial_port *port, unsigned char *ch)
 		if (newMSR & UART_MSR_TERI)
 			port_priv->icount.rng++;
 
-		wake_up_interruptible(&port_priv->delta_msr_wait);
+		wake_up_interruptible(&port->delta_msr_wait);
 	}
 }
 
-- 
1.8.1.2

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