pty: Hold ctrl_lock for packet mode updates

Updates to the packet mode enable require holding the ctrl_lock;
the serialization prevents corruption of adjacent fields.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Reviewed-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 2 insertions, 0 deletions

diff --git a/drivers/tty/pty.c b/drivers/tty/pty.c
index bcec4c71a408..7a1a53819e22 100644
--- a/drivers/tty/pty.c
+++ b/drivers/tty/pty.c
@@ -47,7 +47,9 @@ static void pty_close(struct tty_struct *tty, struct file *filp)
         set_bit(TTY_IO_ERROR, &tty->flags);
         wake_up_interruptible(&tty->read_wait);
         wake_up_interruptible(&tty->write_wait);
+        spin_lock_irq(&tty->ctrl_lock);
         tty->packet = 0;
+        spin_unlock_irq(&tty->ctrl_lock);
         /* Review - krefs on tty_link ?? */
         if (!tty->link)
                 return;