$OpenBSD: patch-libproxy_modules_ignore_ip_cpp,v 1.1 2016/04/18 17:44:40 awolk Exp $
https://github.com/libproxy/libproxy/issues/24
--- libproxy/modules/ignore_ip.cpp.orig	Mon Apr 18 18:14:53 2016
+++ libproxy/modules/ignore_ip.cpp	Mon Apr 18 18:15:26 2016
@@ -147,7 +147,7 @@ class ip_ignore_extension : public ignore_extension { 
 			else
 			{
 				/* If CIDR notation was used, get the netmask */
-				if (sscanf(mask.c_str(), "%d", &cidr) == 1)
+				if (ign_ip && sscanf(mask.c_str(), "%d", &cidr) == 1)
 					net_ip = sockaddr_from_cidr(ign_ip->sa_family, cidr);
 			}
 
