From 4f0755d6d41055be091d3dea477697a2617e1505 Mon Sep 17 00:00:00 2001
From: Jesse Barnes <jbarnes@jbarnes-t61.(none)>
Date: Mon, 17 Mar 2008 08:33:01 -0700
Subject: [PATCH] Fail CRTC configuration if !vtSema

Unless we check for vtSema before calling into the CRTC and output callbacks,
we may end up trying to access video memory that no longer exists, leading to a
crash.  So if we don't have vtSema, return FALSE to the caller, indicating that
we didn't do anything.

Fixes #14444.
(cherry picked from commit bee2ddf35f75086cee951142098637f2c756b96b)
---
 hw/xfree86/modes/xf86RandR12.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/hw/xfree86/modes/xf86RandR12.c b/hw/xfree86/modes/xf86RandR12.c
index 96718399b..14c2d41c1 100644
--- a/hw/xfree86/modes/xf86RandR12.c
+++ b/hw/xfree86/modes/xf86RandR12.c
@@ -717,6 +717,9 @@ xf86RandR12CrtcSet (ScreenPtr	pScreen,
     xf86CrtcPtr		*save_crtcs;
     Bool		save_enabled = crtc->enabled;
 
+    if (!crtc->scrn->vtSema)
+	return FALSE;
+
     save_crtcs = xalloc(config->num_output * sizeof (xf86CrtcPtr));
     if ((randr_mode != NULL) != crtc->enabled)
 	changed = TRUE;