linux-kernel - [PATCH 1/1] fix - ensure we don't use bootconsoles after init has been released

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Message-Id: <200708212314.58656.rgetz@blackfin.uclinux.org>
Date:	Tue, 21 Aug 2007 23:14:58 -0400
From:	Robin Getz <rgetz@...ckfin.uclinux.org>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	torvalds@...ux-foundation.org, linux-kernel@...r.kernel.org,
	"Gerd Hoffmann" <kraxel@...hat.com>,
	"Paul Mundt" <lethal@...ux-sh.org>,
	Mike Frysinger <vapier.adi@...il.com>
Subject: [PATCH 1/1] fix - ensure we don't use bootconsoles after init has been released

From: Robin Getz <rgetz@...ckfin.uclinux.org>

Gerd Hoffmann pointed out that my patch from yesterday can lead 
to a null pointer dereference if the kernel is booted with no
console, and no earlyprintk defined. This fixes that issue.

 printk.c |   10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

Signed-off-by: Robin Getz <rgetz@...ckfin.uclinux.org>

---

Index: linux-2.6.x/kernel/printk.c
===================================================================
--- linux-2.6.x/kernel/printk.c	
+++ linux-2.6.x/kernel/printk.c
@@ -1106,10 +1106,12 @@
 
 static int __init disable_boot_consoles(void)
 {
-	if (console_drivers->flags & CON_BOOT) {
-		printk(KERN_INFO "turn off boot console %s%d\n",
-			console_drivers->name, console_drivers->index);
-		return unregister_console(console_drivers);
+	if (console_drivers != NULL) {
+		if (console_drivers->flags & CON_BOOT) {
+			printk(KERN_INFO "turn off boot console %s%d\n",
+				console_drivers->name, console_drivers->index);
+			return unregister_console(console_drivers);
+		}
 	}
 	return 0;
 }
-
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