Bug #23295288: HANDLE_FATAL_SIGNAL (SIG=11) IN

               GET_SERVER_FROM_TABLE_TO_CACHE

Description:- Server received SIG11 in the function,
"get_server_from_table_to_cache()".

Analysis:- Defining a server with a blank name is not
handled properly.

Fix:- Modified "get_server_from_table_to_cache()" to
take care of blank server name.

sql/sql_yacc.yy

 /*
-   Copyright (c) 2000, 2015, Oracle and/or its affiliates. All rights reserved.
+   Copyright (c) 2000, 2016, Oracle and/or its affiliates. All rights reserved.
 
    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -2148,6 +2148,11 @@ server_def:
           ident_or_text
           OPTIONS_SYM '(' server_options_list ')'
           {
+            if ($2.length == 0)
+            {
+              my_error(ER_WRONG_VALUE, MYF(0), "server name", "");
+              MYSQL_YYABORT;
+            }
             Lex->server_options.server_name= $2.str;
             Lex->server_options.server_name_length= $2.length;
             Lex->server_options.scheme= $6.str;