Fix for bug #20204: "order by" changes the results returned

Item_substr's results are improperly stored in a temporary table due to       
wrongly calculated max_length value for multi-byte charsets if two            
arguments specified.                                                          

1 files changed, 2 insertions, 1 deletions

diff --git a/sql/item_strfunc.cc b/sql/item_strfunc.cc
index 1ef11945bd5..98888226e58 100644
--- a/sql/item_strfunc.cc
+++ b/sql/item_strfunc.cc
@@ -1109,12 +1109,13 @@ void Item_func_substr::fix_length_and_dec()
   }
   if (arg_count == 3 && args[2]->const_item())
   {
-    int32 length= (int32) args[2]->val_int() * collation.collation->mbmaxlen;
+    int32 length= (int32) args[2]->val_int();
     if (length <= 0)
       max_length=0; /* purecov: inspected */
     else
       set_if_smaller(max_length,(uint) length);
   }
+  max_length*= collation.collation->mbmaxlen;
 }