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>
diff --git a/drivers/usb/serial/mct_u232.c b/drivers/usb/serial/mct_u232.c
index a64d420..06d5a60 100644
--- a/drivers/usb/serial/mct_u232.c
+++ b/drivers/usb/serial/mct_u232.c
@@ -114,8 +114,6 @@
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 @@
return -ENOMEM;
spin_lock_init(&priv->lock);
- init_waitqueue_head(&priv->msr_wait);
usb_set_serial_port_data(port, priv);
@@ -601,7 +598,7 @@
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 @@
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);