tty: Prevent tty_port destruction if tty not released
If the tty driver mistakenly drops the last port reference
before the tty has been released, issue a diagnostic and
abort the port destruction.
This will leak memory and may zombify the port, but might
otherwise keep the machine in runnable state.
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/tty/tty_port.c b/drivers/tty/tty_port.c
index f597e88..7efbca4 100644
--- a/drivers/tty/tty_port.c
+++ b/drivers/tty/tty_port.c
@@ -140,6 +140,10 @@
static void tty_port_destructor(struct kref *kref)
{
struct tty_port *port = container_of(kref, struct tty_port, kref);
+
+ /* check if last port ref was dropped before tty release */
+ if (WARN_ON(port->itty))
+ return;
if (port->xmit_buf)
free_page((unsigned long)port->xmit_buf);
tty_port_destroy(port);
