[ 3.5.y.z extended stable ] Patch "USB: f81232: fix use-after-free in TIOCMIWAIT" has been added to staging queue

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

    USB: f81232: fix use-after-free in TIOCMIWAIT

to the linux-3.5.y-queue branch of the 3.5.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.5.y-queue

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.5.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From 5f1fcae438b9dc6ff65c8c4fdb06b022e5b50cb4 Mon Sep 17 00:00:00 2001
From: Johan Hovold <jhovold at gmail.com>
Date: Tue, 19 Mar 2013 09:21:14 +0100
Subject: [PATCH] USB: f81232: fix use-after-free in TIOCMIWAIT

commit 508f940f1407656076a2e7d8f7fa059b567ecac2 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 at gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
[ luis: backport to 3.5; adjust context ]
Luis Henriques <luis.henriques at canonical.com>
---
 drivers/usb/serial/f81232.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/usb/serial/f81232.c b/drivers/usb/serial/f81232.c
index 499b15f..ea88b47 100644
--- a/drivers/usb/serial/f81232.c
+++ b/drivers/usb/serial/f81232.c
@@ -49,7 +49,6 @@ MODULE_DEVICE_TABLE(usb, id_table);

 struct f81232_private {
 	spinlock_t lock;
-	wait_queue_head_t delta_msr_wait;
 	u8 line_control;
 	u8 line_status;
 };
@@ -114,7 +113,7 @@ static void f81232_process_read_urb(struct urb *urb)
 	line_status = priv->line_status;
 	priv->line_status &= ~UART_STATE_TRANSIENT_MASK;
 	spin_unlock_irqrestore(&priv->lock, flags);
-	wake_up_interruptible(&priv->delta_msr_wait);
+	wake_up_interruptible(&port->delta_msr_wait);

 	if (!urb->actual_length)
 		return;
@@ -262,11 +261,14 @@ static int wait_modem_info(struct usb_serial_port *port, unsigned int arg)
 	spin_unlock_irqrestore(&priv->lock, flags);

 	while (1) {
-		interruptible_sleep_on(&priv->delta_msr_wait);
+		interruptible_sleep_on(&port->delta_msr_wait);
 		/* see if a signal did it */
 		if (signal_pending(current))
 			return -ERESTARTSYS;

+		if (port->serial->disconnected)
+			return -EIO;
+
 		spin_lock_irqsave(&priv->lock, flags);
 		status = priv->line_status;
 		spin_unlock_irqrestore(&priv->lock, flags);
@@ -329,7 +331,6 @@ static int f81232_startup(struct usb_serial *serial)
 		if (!priv)
 			goto cleanup;
 		spin_lock_init(&priv->lock);
-		init_waitqueue_head(&priv->delta_msr_wait);
 		usb_set_serial_port_data(serial->port[i], priv);
 	}
 	return 0;
--
1.8.1.2