Index: sys/netpfil/pf/pf_if.c
===================================================================
--- sys/netpfil/pf/pf_if.c
+++ sys/netpfil/pf/pf_if.c
@@ -841,6 +841,14 @@
 	kif->pfik_flags = kkif->pfik_flags;
 	kif->pfik_tzero = kkif->pfik_tzero;
 	kif->pfik_rulerefs = kkif->pfik_rulerefs;
+	/*
+	 * Userspace relies on this pointer to decide if this is a group or
+	 * not. We don't want to share the actual pointer, because it's
+	 * useless to userspace and leaks kernel memory layout information.
+	 * So instead we provide 0xdeadc0de as 'true' and NULL as 'false'.
+	 */
+	kif->pfik_group =
+	    kkif->pfik_group ? (struct ifg_group *)0xdeadc0de : NULL;
 }
 
 void