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From 30c077f228f563e4e1f4115b345577d9fd393b68 Mon Sep 17 00:00:00 2001
From: Peter Hutterer <peter.hutterer@redhat.com>
Date: Fri, 24 Oct 2008 15:06:49 +1030
Subject: [PATCH] dix: extra sanity-checks against potential NULL-dereferences. #434807

Two minor code paths could potentially crash the server:
- if scr is NULL, we shouldn't try to dereference it.
- if GPE is called with buttons != 0 but the event is not a
  ButtonPress or ButtonRelease, the button mapping may dereference a NULL
  pointer.

Admittedly the second should never happen, but better to guard against it.
---
 dix/getevents.c |    6 ++++++
 1 files changed, 6 insertions(+), 0 deletions(-)

diff --git a/dix/getevents.c b/dix/getevents.c
index 1e0edbf..923744d 100644
--- a/dix/getevents.c
+++ b/dix/getevents.c
@@ -537,6 +537,9 @@ GetPointerEvents(xEvent *events, DeviceIntPtr pDev, int type, int buttons,
     ScreenPtr scr = miPointerGetScreen(pDev);
 
     /* Sanity checks. */
+    if (!scr)
+        return 0;
+
     if (type != MotionNotify && type != ButtonPress && type != ButtonRelease)
         return 0;
 
@@ -548,6 +551,9 @@ GetPointerEvents(xEvent *events, DeviceIntPtr pDev, int type, int buttons,
     if (!pDev->valuator)
         return 0;
 
+    if (buttons && !pDev->button)
+        return 0;
+
     if (!coreOnly && pDev->coreEvents)
         num_events = 2;
     else
-- 
1.6.0.3