We can arrive here early on, before the filter is set.  Check for a null
filter.

reactos/drivers/net/ndis/ndis

diff -u -r1.2 -r1.3
--- efilter.c	23 Nov 2004 18:58:47 -0000	1.2
+++ efilter.c	16 Dec 2004 07:50:06 -0000	1.3
@@ -83,6 +83,10 @@

  *     PacketSize          = Total size of received packet
  */
 {

+    /* Not sure if this is a valid thing to do, but we do arrive here early
+     * in the boot process with Filter NULL.  We need to investigate whether
+     * this should be handled or not allowed. */
+    if( !Filter ) return;

     MiniIndicateData((PLOGICAL_ADAPTER)Filter->Miniport,
 		     MacReceiveContext,
 		     HeaderBuffer,