Patch "tty: Fix GPF in flush_to_ldisc(), part 2" has been added to the 4.4-stable tree

[<gregkh@linuxfoundation.org>]

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

    tty: Fix GPF in flush_to_ldisc(), part 2

to the 4.4-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:
     tty-fix-gpf-in-flush_to_ldisc-part-2.patch
and it can be found in the queue-4.4 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 f33798deecbd59a2955f40ac0ae2bc7dff54c069 Mon Sep 17 00:00:00 2001
From: Peter Hurley <peter@hurleysoftware.com>
Date: Sun, 10 Jan 2016 20:36:12 -0800
Subject: tty: Fix GPF in flush_to_ldisc(), part 2

From: Peter Hurley <peter@hurleysoftware.com>

commit f33798deecbd59a2955f40ac0ae2bc7dff54c069 upstream.

commit 9ce119f318ba ("tty: Fix GPF in flush_to_ldisc()") fixed a
GPF caused by a line discipline which does not define a receive_buf()
method.

However, the vt driver (and speakup driver also) pushes selection
data directly to the line discipline receive_buf() method via
tty_ldisc_receive_buf(). Fix the same problem in tty_ldisc_receive_buf().

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 include/linux/tty.h |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/include/linux/tty.h
+++ b/include/linux/tty.h
@@ -594,7 +594,7 @@ static inline int tty_ldisc_receive_buf(
 		count = ld->ops->receive_buf2(ld->tty, p, f, count);
 	else {
 		count = min_t(int, count, ld->tty->receive_room);
-		if (count)
+		if (count && ld->ops->receive_buf)
 			ld->ops->receive_buf(ld->tty, p, f, count);
 	}
 	return count;


Patches currently in stable-queue which might be from peter@hurleysoftware.com are

queue-4.4/tty-fix-gpf-in-flush_to_ldisc-part-2.patch
queue-4.4/8250-use-callbacks-to-access-uart_dll-uart_dlm.patch
queue-4.4/net-irda-fix-use-after-free-in-irtty_open.patch