[PATCH] drivers/char/tty_io.c: Avoid panic when no console is configured.

[Will Newton]

When no console is configured tty_open tries to call kref_get on a NULL
pointer, return ENODEV instead.

Signed-off-by: Will Newton <will.newton@xxxxxxxxx>
---
 drivers/char/tty_io.c |   15 +++++++++------
 1 files changed, 9 insertions(+), 6 deletions(-)

diff --git a/drivers/char/tty_io.c b/drivers/char/tty_io.c
index 59f4721..1412a8d 100644
--- a/drivers/char/tty_io.c
+++ b/drivers/char/tty_io.c
@@ -1795,12 +1795,15 @@ retry_open:
 	}
 #endif
 	if (device == MKDEV(TTYAUX_MAJOR, 1)) {
-		driver = tty_driver_kref_get(console_device(&index));
-		if (driver) {
-			/* Don't let /dev/console block */
-			filp->f_flags |= O_NONBLOCK;
-			noctty = 1;
-			goto got_driver;
+		struct tty_driver *console_driver = console_device(&index);
+		if (console_driver) {
+			driver = tty_driver_kref_get(console_driver);
+			if (driver) {
+				/* Don't let /dev/console block */
+				filp->f_flags |= O_NONBLOCK;
+				noctty = 1;
+				goto got_driver;
+			}
 		}
 		mutex_unlock(&tty_mutex);
 		return -ENODEV;
-- 
1.5.5.2
From 52399d4ddbe920874009cf4dff80a8b08b071167 Mon Sep 17 00:00:00 2001
From: Will Newton <will.newton@xxxxxxxxx>
Date: Thu, 20 Nov 2008 14:19:05 +0000
Subject: [PATCH] drivers/char/tty_io.c: Avoid panic when no console is configured.

When no console is configured tty_open tries to call kref_get on a NULL
pointer, return ENODEV instead.

Signed-off-by: Will Newton <will.newton@xxxxxxxxx>
---
 drivers/char/tty_io.c |   15 +++++++++------
 1 files changed, 9 insertions(+), 6 deletions(-)

diff --git a/drivers/char/tty_io.c b/drivers/char/tty_io.c
index 59f4721..1412a8d 100644
--- a/drivers/char/tty_io.c
+++ b/drivers/char/tty_io.c
@@ -1795,12 +1795,15 @@ retry_open:
 	}
 #endif
 	if (device == MKDEV(TTYAUX_MAJOR, 1)) {
-		driver = tty_driver_kref_get(console_device(&index));
-		if (driver) {
-			/* Don't let /dev/console block */
-			filp->f_flags |= O_NONBLOCK;
-			noctty = 1;
-			goto got_driver;
+		struct tty_driver *console_driver = console_device(&index);
+		if (console_driver) {
+			driver = tty_driver_kref_get(console_driver);
+			if (driver) {
+				/* Don't let /dev/console block */
+				filp->f_flags |= O_NONBLOCK;
+				noctty = 1;
+				goto got_driver;
+			}
 		}
 		mutex_unlock(&tty_mutex);
 		return -ENODEV;
-- 
1.5.5.2