linux-kernel - [PATCH] tty: fix read of tty->pgrp outside of ctrl

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Message-Id: <20190310214347.12015-1-dave@sp4m.net>
Date:   Sun, 10 Mar 2019 21:43:47 +0000
From:   "David Emett" <dave@...m.net>
To:     unlisted-recipients:; (no To-header on input)
Cc:     David Emett <dave@...m.net>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Slaby <jslaby@...e.com>, linux-kernel@...r.kernel.org
Subject: [PATCH] tty: fix read of tty->pgrp outside of ctrl_lock

The intention was clearly to use the tty_pgrp local variable rather than
re-read tty->pgrp outside of ctrl_lock, so do that.

This bug was introduced by commit 2812d9e9fd94 ("tty: Combine
SIGTTOU/SIGTTIN handling").

Signed-off-by: David Emett <dave@...m.net>
---
 drivers/tty/tty_jobctrl.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/tty/tty_jobctrl.c b/drivers/tty/tty_jobctrl.c
index c4ecd66fafef..eac05227588d 100644
--- a/drivers/tty/tty_jobctrl.c
+++ b/drivers/tty/tty_jobctrl.c
@@ -44,7 +44,7 @@ int __tty_check_change(struct tty_struct *tty, int sig)
 	tty_pgrp = tty->pgrp;
 	spin_unlock_irqrestore(&tty->ctrl_lock, flags);
 
-	if (tty_pgrp && pgrp != tty->pgrp) {
+	if (tty_pgrp && pgrp != tty_pgrp) {
 		if (is_ignored(sig)) {
 			if (sig == SIGTTIN)
 				ret = -EIO;
-- 
2.17.1