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Commit cf1d2444 authored by Johan Hovold's avatar Johan Hovold Committed by Greg Kroah-Hartman
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USB: mct_u232: fix use-after-free in TIOCMIWAIT 



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.

Cc: stable <stable@vger.kernel.org>
Signed-off-by: default avatarJohan Hovold <jhovold@gmail.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 7b245969

drivers/usb/serial/mct_u232.c

+7 −6
Original line number Diff line number Diff line
@@ -114,8 +114,6 @@ struct mct_u232_private { 
	unsigned char	     last_msr;      /* Modem Status Register */

	unsigned int	     rx_flags;      /* Throttling flags */

	struct async_icount  icount;

	wait_queue_head_t    msr_wait;	/* for handling sleeping while waiting

						for msr change to happen */

};



#define THROTTLED		0x01
@@ -409,7 +407,6 @@ static int mct_u232_port_probe(struct usb_serial_port *port) 
		return -ENOMEM;



	spin_lock_init(&priv->lock);

	init_waitqueue_head(&priv->msr_wait);



	usb_set_serial_port_data(port, priv);
@@ -601,7 +598,7 @@ static void mct_u232_read_int_callback(struct urb *urb) 
		tty_kref_put(tty);

	}

#endif

	wake_up_interruptible(&priv->msr_wait);

	wake_up_interruptible(&port->delta_msr_wait);

	spin_unlock_irqrestore(&priv->lock, flags);

exit:

	retval = usb_submit_urb(urb, GFP_ATOMIC);
@@ -810,13 +807,17 @@ static int mct_u232_ioctl(struct tty_struct *tty, 
		cprev = mct_u232_port->icount;

		spin_unlock_irqrestore(&mct_u232_port->lock, flags);

		for ( ; ; ) {

			prepare_to_wait(&mct_u232_port->msr_wait,

			prepare_to_wait(&port->delta_msr_wait,

					&wait, TASK_INTERRUPTIBLE);

			schedule();

			finish_wait(&mct_u232_port->msr_wait, &wait);

			finish_wait(&port->delta_msr_wait, &wait);

			/* see if a signal did it */

			if (signal_pending(current))

				return -ERESTARTSYS;



			if (port->serial->disconnected)

				return -EIO;



			spin_lock_irqsave(&mct_u232_port->lock, flags);

			cnow = mct_u232_port->icount;

			spin_unlock_irqrestore(&mct_u232_port->lock, flags);