Index: programs/Xserver/hw/xfree86/common/xf86MiscExt.c
===================================================================
RCS file: /home/eich/cvs/xc/programs/Xserver/hw/xfree86/common/xf86MiscExt.c,v
retrieving revision 1.1.1.15
diff -u -r1.1.1.15 xf86MiscExt.c
--- programs/Xserver/hw/xfree86/common/xf86MiscExt.c	6 Jul 2004 15:12:40 -0000	1.1.1.15
+++ programs/Xserver/hw/xfree86/common/xf86MiscExt.c	17 Mar 2005 18:39:52 -0000
@@ -166,6 +166,11 @@
 	*devname = xf86FindOptionValue(pInfo->options, "Device");
 	pMse = pInfo->private;
 
+	if (pMse->magic != MOUSE_MAGIC
+	    || pMse->size != sizeof(*pMse))
+	    return FALSE;
+	    
+
 	mseptr->type =		MapMseProtoToMisc(pMse->protocolID);
 	mseptr->baudrate =	pMse->baudRate;
 	mseptr->samplerate =	pMse->sampleRate;
@@ -533,6 +538,11 @@
 
 	pInfo = mse->private;
 	pMse = pInfo->private;
+
+	if (pMse->magic != MOUSE_MAGIC
+	    || pMse->size != sizeof(*pMse))
+	    return MISC_RET_NOMODULE;
+	    
 	oldflags = pMse->mouseFlags;
 	
 	newProtocol = MapMseMiscToProto(mse->type);
Index: programs/Xserver/hw/xfree86/os-support/xf86OSmouse.h
===================================================================
RCS file: /home/eich/cvs/xc/programs/Xserver/hw/xfree86/os-support/xf86OSmouse.h,v
retrieving revision 1.1.1.21
diff -u -r1.1.1.21 xf86OSmouse.h
--- programs/Xserver/hw/xfree86/os-support/xf86OSmouse.h	1 Nov 2004 16:46:39 -0000	1.1.1.21
+++ programs/Xserver/hw/xfree86/os-support/xf86OSmouse.h	17 Mar 2005 18:39:52 -0000
@@ -204,7 +204,11 @@
 			      int dx, int dy, int dz, int dw);
 typedef void (*MouseCommonOptProc)(InputInfoPtr pInfo);
 
+#define MOUSE_MAGIC 15031995
+
 typedef struct _MouseDevRec {
+    unsigned long	magic;
+    int			size;
     PtrCtrlProcPtr	Ctrl;
     PostMseEventProc	PostEvent;
     MouseCommonOptProc	CommonOptions;