linux-kernel - [PATCH 1/2] drivers/char/tty_io.c: Avoid panic when no console is configured.

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Date:	Mon, 01 Dec 2008 11:36:06 +0000
From:	Alan Cox <alan@...rguk.ukuu.org.uk>
To:	torvalds@...ux-foundation.org, linux-kernel@...r.kernel.org
Subject: [PATCH 1/2] drivers/char/tty_io.c: Avoid panic when no console is
	configured.

From: \"Will Newton\" <will.newton@...il.com>

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@...il.com>
Signed-off-by: Alan Cox <alan@...hat.com>
---

 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 966be86..ac73fd9 100644
--- a/drivers/char/tty_io.c
+++ b/drivers/char/tty_io.c
@@ -1793,12 +1793,15 @@ 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;

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