From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Message-Id: <20130325010532.919206744@decadent.org.uk> Date: Mon, 25 Mar 2013 01:06:51 +0000 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: akpm@linux-foundation.org, Johan Hovold , Greg Kroah-Hartman Subject: [ 087/104] USB: cypress_m8: fix use-after-free in TIOCMIWAIT Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit In-Reply-To: <20130325010524.240972766@decadent.org.uk> Sender: linux-kernel-owner@vger.kernel.org List-ID: 3.2-stable review patch. If anyone has any objections, please let me know. ------------------ From: Johan Hovold commit 356050d8b1e526db093e9d2c78daf49d6bf418e3 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. Also remove bogus test for private data pointer being NULL as it is never assigned in the loop. Signed-off-by: Johan Hovold Signed-off-by: Greg Kroah-Hartman Signed-off-by: Ben Hutchings --- drivers/usb/serial/cypress_m8.c | 14 ++++++++------ 1 file changed, 8 insertions(+), 6 deletions(-) --- a/drivers/usb/serial/cypress_m8.c +++ b/drivers/usb/serial/cypress_m8.c @@ -150,7 +150,6 @@ struct cypress_private { int baud_rate; /* stores current baud rate in integer form */ int isthrottled; /* if throttled, discard reads */ - wait_queue_head_t delta_msr_wait; /* used for TIOCMIWAIT */ char prev_status, diff_status; /* used for TIOCMIWAIT */ /* we pass a pointer to this as the argument sent to cypress_set_termios old_termios */ @@ -488,7 +487,6 @@ static int generic_startup(struct usb_se kfree(priv); return -ENOMEM; } - init_waitqueue_head(&priv->delta_msr_wait); usb_reset_configuration(serial->dev); @@ -928,12 +926,16 @@ static int cypress_ioctl(struct tty_stru switch (cmd) { /* This code comes from drivers/char/serial.c and ftdi_sio.c */ case TIOCMIWAIT: - while (priv != NULL) { - interruptible_sleep_on(&priv->delta_msr_wait); + for (;;) { + interruptible_sleep_on(&port->delta_msr_wait); /* see if a signal did it */ if (signal_pending(current)) return -ERESTARTSYS; - else { + + if (port->serial->disconnected) + return -EIO; + + { char diff = priv->diff_status; if (diff == 0) return -EIO; /* no change => error */ @@ -1261,7 +1263,7 @@ static void cypress_read_int_callback(st if (priv->current_status != priv->prev_status) { priv->diff_status |= priv->current_status ^ priv->prev_status; - wake_up_interruptible(&priv->delta_msr_wait); + wake_up_interruptible(&port->delta_msr_wait); priv->prev_status = priv->current_status; } spin_unlock_irqrestore(&priv->lock, flags);