From a87b197aa8082bdd3c440c76f97088b190dd8dd4 Mon Sep 17 00:00:00 2001
From: Jo-Philipp Wich <jow@openwrt.org>
Date: Fri, 8 Aug 2008 13:45:09 +0000
Subject: [PATCH] * luci/libs:	properly handle overflows in luci.ip.add()

---
 libs/core/luasrc/ip.lua | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/libs/core/luasrc/ip.lua b/libs/core/luasrc/ip.lua
index 2fe71297d..761a78110 100644
--- a/libs/core/luasrc/ip.lua
+++ b/libs/core/luasrc/ip.lua
@@ -382,8 +382,10 @@ function cidr.add( self, amount )
 		local add = ( #shorts > 0 ) and table.remove( shorts, #shorts ) or 0
 		if ( data[pos] + add ) > 0xFFFF then
 			data[pos] = ( data[pos] + add ) % 0xFFFF
-			if pos > 2 then
+			if pos > 1 then
 				data[pos-1] = data[pos-1] + ( add - data[pos] )
+			else
+				return nil
 			end
 		else
 			data[pos] = data[pos] + add
-- 
2.11.0