Land #11497, file: RHOSTS fix for exploits

lib/msf/ui/console/command_dispatcher/exploit.rb

@@ -165,9 +165,12 @@ class Exploit
     end
 
     rhosts = mod.datastore['RHOSTS']
-    rhosts_range = Rex::Socket::RangeWalker.new(rhosts)
+    if rhosts
+      rhosts_opt = Msf::OptAddressRange.new('RHOSTS')
+      rhosts_range = Rex::Socket::RangeWalker.new(rhosts_opt.normalize(rhosts))
+    end
     # For multiple targets exploit attempts.
-    if rhosts && rhosts_range.length.to_i > 1
+    if rhosts_range && rhosts_range.length > 1
       opts[:multi] = true
       rhosts_range.each do |rhost|
         nmod = mod.replicant
@@ -196,7 +199,7 @@ class Exploit
     # For single target or no rhosts option.
     else
       # avoid bug when the cidr of rhosts is 32, like 8.8.8.8/32
-      if rhosts_range.length == 1
+      if rhosts_range && rhosts_range.length == 1
         mod.datastore['RHOST'] = (Rex::Socket.addr_itoa(rhosts_range.ranges.first.start))
       end
       session = exploit_single(mod, opts)