[ 3.5.y.z extended stable ] Patch "USB: ssu100: fix use-after-free in TIOCMIWAIT" has been added to staging queue

Luis Henriques luis.henriques at canonical.com
Mon Mar 25 18:03:15 UTC 2013


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

    USB: ssu100: 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 c805a1c092aae83a62892659f76c096739205520 Mon Sep 17 00:00:00 2001
From: Johan Hovold <jhovold at gmail.com>
Date: Tue, 19 Mar 2013 09:21:25 +0100
Subject: [PATCH] USB: ssu100: fix use-after-free in TIOCMIWAIT

commit 43a66b4c417ad15f6d2f632ce67ad195bdf999e8 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: backported to 3.5; adjust context ]
Luis Henriques <luis.henriques at canonical.com>
---
 drivers/usb/serial/ssu100.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/drivers/usb/serial/ssu100.c b/drivers/usb/serial/ssu100.c
index c4409b1..3ad10b5 100644
--- a/drivers/usb/serial/ssu100.c
+++ b/drivers/usb/serial/ssu100.c
@@ -65,7 +65,6 @@ struct ssu100_port_private {
 	spinlock_t status_lock;
 	u8 shadowLSR;
 	u8 shadowMSR;
-	wait_queue_head_t delta_msr_wait; /* Used for TIOCMIWAIT */
 	struct async_icount icount;
 };

@@ -366,8 +365,9 @@ static int wait_modem_info(struct usb_serial_port *port, unsigned int arg)
 	spin_unlock_irqrestore(&priv->status_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)));
@@ -375,6 +375,9 @@ 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->status_lock, flags);
 		cur = priv->icount;
 		spin_unlock_irqrestore(&priv->status_lock, flags);
@@ -455,7 +458,6 @@ static int ssu100_attach(struct usb_serial *serial)
 	}

 	spin_lock_init(&priv->status_lock);
-	init_waitqueue_head(&priv->delta_msr_wait);
 	usb_set_serial_port_data(port, priv);

 	return ssu100_initdevice(serial->dev);
@@ -536,7 +538,7 @@ static void ssu100_update_msr(struct usb_serial_port *port, u8 msr)
 			priv->icount.dcd++;
 		if (msr & UART_MSR_TERI)
 			priv->icount.rng++;
-		wake_up_interruptible(&priv->delta_msr_wait);
+		wake_up_interruptible(&port->delta_msr_wait);
 	}
 }

--
1.8.1.2





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