TTY: pty, fix tty buffers leak

After commit "TTY: move tty buffers to tty_port", the tty buffers are
not freed in some drivers. This is because tty_port_destructor is not
called whenever a tty_port is freed. This was an assumption I counted
with but was unfortunately untrue. So fix the drivers to fulfil this
assumption.

PTY is one of those, here we just need to use tty_port_put instead of
kfree. (Assuming tty_port_destructor does not need port->ops to be set
which we change here too.)

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

2 files changed, 2 insertions, 2 deletions

diff --git a/drivers/tty/pty.c b/drivers/tty/pty.c
index 0ce0b3ec2bb0..a541ec875932 100644
--- a/drivers/tty/pty.c
+++ b/drivers/tty/pty.c
@@ -408,7 +408,7 @@ static void pty_unix98_shutdown(struct tty_struct *tty)
 static void pty_cleanup(struct tty_struct *tty)
 {
         tty->port->itty = NULL;
-        kfree(tty->port);
+        tty_port_put(tty->port);
 }
 
 /* Traditional BSD devices */
diff --git a/drivers/tty/tty_port.c b/drivers/tty/tty_port.c
index 416b42f7c346..fdc42c2d565f 100644
--- a/drivers/tty/tty_port.c
+++ b/drivers/tty/tty_port.c
@@ -128,7 +128,7 @@ static void tty_port_destructor(struct kref *kref)
         if (port->xmit_buf)
                 free_page((unsigned long)port->xmit_buf);
         tty_buffer_free_all(port);
-        if (port->ops->destruct)
+        if (port->ops && port->ops->destruct)
                 port->ops->destruct(port);
         else
                 kfree(port);