Commit 4ab4631b authored by unknown's avatar unknown
Browse files

Bug#19136: Crashing log-bin and uninitialized user variables in a derived table 

The reason of the bug is in that `get_var_with_binlog' performs missed
assingment of
the variables as side-effect. Doing that it eventually calls
`free_underlaid_joins' to pass as an argument `thd->lex->select_lex' of the lex
which belongs to the user query, not 
to one which is emulated i.e SET @var1:=NULL.


`get_var_with_binlog' is refined to supply a temporary lex to sql_set_variables's stack.


mysql-test/r/rpl_user_variables.result:
  results changed
mysql-test/t/rpl_user_variables.test:
  a problematic query to be binlogged is added
sql/item_func.cc:
  BUG#19136: Crashing log-bin and uninitialized user variables
  
  The reason of the bug is in that how `get_var_with_binlog' performs missed
  assingment of the variables: `free_underlaid_joins' gets as an argument `thd->lex->select_lex'
  which belongs to the user query, not to one which is emulated i.e SET @var1:=NULL.
  
  `get_var_with_binlog' is refined to supply a temporary lex to sql_set_variables's stack.
parent e38edaef

mysql-test/r/rpl_user_variables.result

+1 −0
Original line number Diff line number Diff line
@@ -105,5 +105,6 @@ slave-bin.000001 1370 User var 2 1370 @`a`=5 
slave-bin.000001	1412	Query	1	1412	use `test`; insert into t1 values (@a),(@a)

slave-bin.000001	1478	User var	2	1478	@`a`=NULL

slave-bin.000001	1503	Query	1	1503	use `test`; insert into t1 values (@a),(@a),(@a*5)

insert into t1 select * FROM (select @var1 union  select @var2) AS t2;

drop table t1;

stop slave;

mysql-test/t/rpl_user_variables.test

+6 −0
Original line number Diff line number Diff line
@@ -47,9 +47,15 @@ connection slave; 
sync_with_master;

select * from t1;

show binlog events from 141;



#

# BUG19136: Crashing log-bin and uninitialized user variables in a derived table

# just to check nothing bad happens anymore

connection master;

insert into t1 select * FROM (select @var1 union  select @var2) AS t2;

drop table t1;

save_master_pos;



connection slave;

sync_with_master;

stop slave;

sql/item_func.cc

+10 −0
Original line number Diff line number Diff line
@@ -2733,14 +2733,24 @@ int get_var_with_binlog(THD *thd, LEX_STRING &name, 
      sql_set_variables(), we could instead manually call check() and update();

      this would save memory and time; but calling sql_set_variables() makes

      one unique place to maintain (sql_set_variables()). 



      Manipulation with lex is necessary since free_underlaid_joins

      is going to release memory belonging to the main query.

    */



    List<set_var_base> tmp_var_list;

    LEX *sav_lex= thd->lex, lex_tmp;

    thd->lex= &lex_tmp;

    lex_start(thd, NULL, 0);

    tmp_var_list.push_back(new set_var_user(new Item_func_set_user_var(name,

                                                                       new Item_null())));

    /* Create the variable */

    if (sql_set_variables(thd, &tmp_var_list))

    {

      thd->lex= sav_lex;

      goto err;

    }

    thd->lex= sav_lex;

    if (!(var_entry= get_variable(&thd->user_vars, name, 0)))

      goto err;

  }