linux-kernel - [PATCH] tty: Fix unreasonable write toward closed pty.

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Date:	Wed, 19 Dec 2012 22:59:19 +0400
From:	Ilya Zykov <ilya@...x.ru>
To:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
CC:	Alan Cox <alan@...ux.intel.com>, Jiri Slaby <jslaby@...e.cz>,
	Peter Hurley <peter@...leysoftware.com>,
	Sasha Levin <levinsasha928@...il.com>,
	linux-serial@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] tty: Fix unreasonable write toward closed pty.

We should not write toward the closed pty. 
Now it happens, if one side close last file descriptor,
and other side in this moment write to it.
It also prevents scheduling unnecessary work.

Signed-off-by: Ilya Zykov <ilya@...x.ru>
---
 drivers/tty/pty.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)

diff --git a/drivers/tty/pty.c b/drivers/tty/pty.c
index a82b399..1ce1362 100644
--- a/drivers/tty/pty.c
+++ b/drivers/tty/pty.c
@@ -116,6 +116,8 @@ static int pty_space(struct tty_struct *to)
 
 static int pty_write(struct tty_struct *tty, const unsigned char *buf, int c)
 {
+	if (test_bit(TTY_OTHER_CLOSED, &tty->flags))
+		return -EIO;
 	struct tty_struct *to = tty->link;
 
 	if (tty->stopped)
--
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