Patch "serdev: ttyport: fix tty locking in close" has been added to the 4.14-stable tree

Patch "serdev: ttyport: fix tty locking in close" has been added to the 4.14-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    serdev: ttyport: fix tty locking in close

to the 4.14-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     serdev-ttyport-fix-tty-locking-in-close.patch
and it can be found in the queue-4.14 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 90dbad8cd6efccbdce109d5ef0724f8434a6cdde Mon Sep 17 00:00:00 2001
From: Johan Hovold <johan@kernel.org>
Date: Fri, 3 Nov 2017 15:30:56 +0100
Subject: serdev: ttyport: fix tty locking in close

From: Johan Hovold <johan@kernel.org>

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>

---
 drivers/tty/serdev/serdev-ttyport.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/drivers/tty/serdev/serdev-ttyport.c
+++ b/drivers/tty/serdev/serdev-ttyport.c
@@ -149,8 +149,10 @@ static void ttyport_close(struct serdev_
 
 	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);
 }


Patches currently in stable-queue which might be from johan@kernel.org are

queue-4.14/serdev-ttyport-fix-null-deref-on-hangup.patch
queue-4.14/serdev-ttyport-fix-tty-locking-in-close.patch
queue-4.14/serdev-ttyport-add-missing-receive_buf-sanity-checks.patch