From: Matthias Reichl hias@horus.com
commit 4466d6d2f80c1193e0845d110277c56da77a6418 upstream.
Commit 2ae0b31e0face ("tty: don't crash in tty_init_dev when missing tty_port") didn't fully prevent the crash as the cleanup path in tty_init_dev() calls release_tty() which dereferences tty->port without checking it for non-null.
Add tty->port checks to release_tty to avoid the kernel crash.
Fixes: 2ae0b31e0face ("tty: don't crash in tty_init_dev when missing tty_port") Signed-off-by: Matthias Reichl hias@horus.com Link: https://lore.kernel.org/r/20201105123432.4448-1-hias@horus.com Cc: stable stable@vger.kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/tty/tty_io.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)
--- a/drivers/tty/tty_io.c +++ b/drivers/tty/tty_io.c @@ -1514,10 +1514,12 @@ static void release_tty(struct tty_struc tty->ops->shutdown(tty); tty_save_termios(tty); tty_driver_remove_tty(tty->driver, tty); - tty->port->itty = NULL; + if (tty->port) + tty->port->itty = NULL; if (tty->link) tty->link->port->itty = NULL; - tty_buffer_cancel_work(tty->port); + if (tty->port) + tty_buffer_cancel_work(tty->port); if (tty->link) tty_buffer_cancel_work(tty->link->port);