From 098b7d6add425aadb0cfe5af34c5d88d5320d33f Mon Sep 17 00:00:00 2001
From: Jo-Philipp Wich <jow@openwrt.org>
Date: Tue, 18 Jun 2013 16:11:56 +0200
Subject: [PATCH] Fix processing of CIDRs with mask 0

---
 iptables.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/iptables.c b/iptables.c
index df0d704..7d91452 100644
--- a/iptables.c
+++ b/iptables.c
@@ -609,7 +609,10 @@ fw3_ipt_rule_in_out(struct fw3_ipt_rule *r,
 static void
 ip4prefix2mask(int prefix, struct in_addr *mask)
 {
-	mask->s_addr = htonl(~((1 << (32 - prefix)) - 1));
+	if (prefix > 0)
+		mask->s_addr = htonl(~((1 << (32 - prefix)) - 1));
+	else
+		mask->s_addr = 0;
 }
 
 #ifndef DISABLE_IPV6
-- 
2.25.1