From 28159eff6badf6181b255f26d1f444abe81c05b7 Mon Sep 17 00:00:00 2001
From: Jason Gerecke <killertofu@gmail.com>
Date: Thu, 30 Apr 2015 18:06:14 -0700
Subject: xfree86: Return NULL from xf86CompatOutput if no compat_output is
 defined

If no compat_output is defined, we inadvertently (attempt to) return
whatever data is at index -1. Instead, return NULL since that's what
callers are expecting.

Reviewed-by: Adam Jackson <ajax@redhat.com>
Signed-off-by: Jason Gerecke <jason.gerecke@wacom.com>
---
 hw/xfree86/modes/xf86Crtc.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/hw/xfree86/modes/xf86Crtc.h b/hw/xfree86/modes/xf86Crtc.h
index 3c5bbcfd5..8b0160845 100644
--- a/hw/xfree86/modes/xf86Crtc.h
+++ b/hw/xfree86/modes/xf86Crtc.h
@@ -745,6 +745,8 @@ xf86CompatOutput(ScrnInfoPtr pScrn)
 {
     xf86CrtcConfigPtr config = XF86_CRTC_CONFIG_PTR(pScrn);
 
+    if (config->compat_output < 0)
+        return NULL;
     return config->output[config->compat_output];
 }
 
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