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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: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Johan Hovold 2013-03-19 09:21:18 +01:00 committed by Greg Kroah-Hartman
parent 7b24596905
commit cf1d244436
1 changed files with 7 additions and 6 deletions
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13
drivers/usb/serial/mct_u232.c
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@ -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);