tty: handle NULL parameters in free_tty_struct()

We sometimes pass NULL pointers to free_tty_struct().  One example where
it can happen is in the error handling code in pty_common_install().

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
index 6087499..6784aae 100644 (file)
--- a/drivers/tty/tty_io.c
+++ b/drivers/tty/tty_io.c
@@ -181,6 +181,8 @@ struct tty_struct *alloc_tty_struct(void)
 
 void free_tty_struct(struct tty_struct *tty)
 {
+       if (!tty)
+               return;
        if (tty->dev)
                put_device(tty->dev);
        kfree(tty->write_buf);