From: Matthew Dillon <dillon@apollo.backplane.com>
Date: Tue, 29 Jan 2013 19:19:22 +0000 (-0800)
Subject: kernel - Attempt to fix NULL pointer dereference during console switch
X-Git-Tag: v3.4.0rc~415
X-Git-Url: http://gitweb.dragonflybsd.org/dragonfly.git/commitdiff_plain/8aefdd25a3f794c7099ac77056d8fa74c28e7bcc

kernel - Attempt to fix NULL pointer dereference during console switch

* Attempt to fix NULL pointer dereference during console switch.
  Bug 2481.

Reported-by: marino
---

diff --git a/sys/dev/misc/syscons/syscons.c b/sys/dev/misc/syscons/syscons.c
index c6a6cb5..afc9bbc 100644
--- a/sys/dev/misc/syscons/syscons.c
+++ b/sys/dev/misc/syscons/syscons.c
@@ -1093,8 +1093,14 @@ scioctl(struct dev_ioctl_args *ap)
 	    lwkt_reltoken(&tty_token);
 	    return error;
 	}
+
+	/*
+	 * scp might be NULL, we aren't sure why.  Check for NULL.
+	 *
+	 * http://bugs.dragonflybsd.org/issues/2481
+	 */
 	scp = SC_STAT(SC_DEV(sc, i));
-	if (scp == scp->sc->cur_scp) {
+	if (scp == NULL || scp == scp->sc->cur_scp) {
 	    lwkt_reltoken(&tty_token);
 	    return 0;
 	}