From owner-freebsd-stable  Sat Apr  7 14:25:47 2001
Delivered-To: freebsd-stable@freebsd.org
Received: from bazooka.unixfreak.org (bazooka.unixfreak.org [63.198.170.138])
	by hub.freebsd.org (Postfix) with ESMTP
	id 8BB8037B424; Sat,  7 Apr 2001 14:25:42 -0700 (PDT)
	(envelope-from dima@unixfreak.org)
Received: from spike.unixfreak.org (spike [63.198.170.139])
	by bazooka.unixfreak.org (Postfix) with ESMTP
	id 2418A3E09; Sat,  7 Apr 2001 14:25:42 -0700 (PDT)
To: current@freebsd.org
Cc: stable@freebsd.org
Subject: syscons panic in userconfig mode (with patch)
Date: Sat, 07 Apr 2001 14:25:42 -0700
From: Dima Dorfman <dima@unixfreak.org>
Message-Id: <20010407212542.2418A3E09@bazooka.unixfreak.org>
Sender: owner-freebsd-stable@FreeBSD.ORG
Precedence: bulk
X-Loop: FreeBSD.ORG

[ cc'd to -stable since that's affected, too ]

Attempting to switch VTYs in userconfig mode will lead to a null
dereference in syscons.  I saw some messages about this on -current,
-stable, or -bugs recently, but I can't find them now.  This is pretty
easy to reproduce: simply boot the kernel with the -c flag
(userconfig), and press ALT+F2 (i386).  As far as I can tell, this
isn't a new bug.

The patch is also pretty trivial.  It just changes the VIRTUAL_TTY
macro not to blindly assume sc->dev[x] is a valid pointer.  It is safe
to have it "return" NULL because any code that uses it must (and does)
already check for that condition since si_tty may also be NULL in some
cases (or at least that's the way I understand it).

Could someone please look it over and, if it's okay, commit it?

Thanks,

					Dima Dorfman
					dima@unixfreak.org


Index: syscons.c
===================================================================
RCS file: /st/src/FreeBSD/src/sys/dev/syscons/syscons.c,v
retrieving revision 1.355
diff -u -r1.355 syscons.c
--- syscons.c	2001/03/26 12:40:39	1.355
+++ syscons.c	2001/04/07 21:02:31
@@ -122,7 +122,8 @@
 
 #define SC_CONSOLECTL	255
 
-#define VIRTUAL_TTY(sc, x) (SC_DEV((sc), (x))->si_tty)
+#define VIRTUAL_TTY(sc, x) (SC_DEV((sc), (x)) != NULL ?	\
+	SC_DEV((sc), (x))->si_tty : NULL)
 
 static	int		debugger;
 

To Unsubscribe: send mail to majordomo@FreeBSD.org
with "unsubscribe freebsd-stable" in the body of the message