From: Johan Hovold <johan@kernel.org>
Date: Fri, 3 Nov 2017 14:30:56 +0000 (+0100)
Subject: serdev: ttyport: fix tty locking in close
X-Git-Tag: v4.14.6~147
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=ce42ed5ae8982360dba581acfafdaff88f2b3fbe;p=users%2Fjedix%2Flinux-maple.git

serdev: ttyport: fix tty locking in close

commit 90dbad8cd6efccbdce109d5ef0724f8434a6cdde upstream.

Make sure to hold the tty lock as required when calling tty-driver
close() (e.g. to avoid racing with hangup()).

Note that the serport active flag is currently set under the lock at
controller open, but really isn't protected by it.

Fixes: cd6484e1830b ("serdev: Introduce new bus for serial attached devices")
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/drivers/tty/serdev/serdev-ttyport.c b/drivers/tty/serdev/serdev-ttyport.c
index ce7fc44f2fe2..7f785d77ba7f 100644
--- a/drivers/tty/serdev/serdev-ttyport.c
+++ b/drivers/tty/serdev/serdev-ttyport.c
@@ -149,8 +149,10 @@ static void ttyport_close(struct serdev_controller *ctrl)
 
 	clear_bit(SERPORT_ACTIVE, &serport->flags);
 
+	tty_lock(tty);
 	if (tty->ops->close)
 		tty->ops->close(tty, NULL);
+	tty_unlock(tty);
 
 	tty_release_struct(tty, serport->tty_idx);
 }