applications/luci-wol: fix XSS

applications/luci-wol/luasrc/model/cbi/wol.lua

@@ -86,7 +86,7 @@ end
 
 function host.write(self, s, val)
 	local host = luci.http.formvalue("cbid.wol.1.mac")
-	if host and #host > 0 then
+	if host and #host > 0 and host:match("^[a-fA-F0-9:]+$") then
 		local cmd
 		local util = luci.http.formvalue("cbid.wol.1.binary") or (
 			has_ewk and "/usr/bin/etherwake" or "/usr/bin/wol"
@@ -127,4 +127,3 @@ end
 
 
 return m
-