From 7ce3ce4be46087f9cc57cb415875abaaa961f734 Mon Sep 17 00:00:00 2001
From: Alan Coopersmith <alan.coopersmith@oracle.com>
Date: Sat, 4 May 2013 09:21:14 -0700
Subject: Use _XEatDataWords to avoid overflow of _XEatData calculations

rep.length is a CARD32, so rep.length << 2 could overflow in 32-bit builds

Signed-off-by: Alan Coopersmith <alan.coopersmith@oracle.com>
---
 configure.ac   |  6 ++++++
 src/Xinerama.c | 19 ++++++++++++++++++-
 2 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/configure.ac b/configure.ac
index e335508..046a1aa 100644
--- a/configure.ac
+++ b/configure.ac
@@ -42,6 +42,12 @@ XORG_CHECK_MALLOC_ZERO
 # Obtain compiler/linker options for depedencies
 PKG_CHECK_MODULES(XINERAMA, x11 xext xextproto [xineramaproto >= 1.1.99.1])
 
+# Check for _XEatDataWords function that may be patched into older Xlib releases
+SAVE_LIBS="$LIBS"
+LIBS="$XINERAMA_LIBS"
+AC_CHECK_FUNCS([_XEatDataWords])
+LIBS="$SAVE_LIBS"
+
 # Allow checking code with lint, sparse, etc.
 XORG_WITH_LINT
 LINT_FLAGS="${LINT_FLAGS} ${XINERAMA_CFLAGS}"
diff --git a/src/Xinerama.c b/src/Xinerama.c
index 7d7e4d8..04189b6 100644
--- a/src/Xinerama.c
+++ b/src/Xinerama.c
@@ -23,6 +23,10 @@ dealings in this Software without prior written authorization from Digital
 Equipment Corporation.
 ******************************************************************/
 
+#ifdef HAVE_CONFIG_H
+# include "config.h"
+#endif
+
 #include <X11/Xlibint.h>
 #include <X11/Xutil.h>
 #include <X11/extensions/Xext.h>
@@ -31,6 +35,19 @@ Equipment Corporation.
 #include <X11/extensions/panoramiXproto.h>
 #include <X11/extensions/Xinerama.h>
 
+#ifndef HAVE__XEATDATAWORDS
+#include <X11/Xmd.h>  /* for LONG64 on 64-bit platforms */
+#include <limits.h>
+
+static inline void _XEatDataWords(Display *dpy, unsigned long n)
+{
+# ifndef LONG64
+    if (n >= (ULONG_MAX >> 2))
+        _XIOError(dpy);
+# endif
+    _XEatData (dpy, n << 2);
+}
+#endif
 
 static XExtensionInfo _panoramiX_ext_info_data;
 static XExtensionInfo *panoramiX_ext_info = &_panoramiX_ext_info_data;
@@ -302,7 +319,7 @@ XineramaQueryScreens(
 
 	    *number = rep.number;
 	} else
-	    _XEatData(dpy, rep.length << 2);
+	    _XEatDataWords(dpy, rep.length);
     } else {
 	*number = 0;
     }
-- 
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