bk commit into 5.1 tree (anozdrin:1.2600) BUG#31111

From: Alexander Nozdrin <alik(at)mysql.com>
Date: Wed Oct 17 2007 - 02:05:55 EDT

Below is the list of changes that have just been committed into a local 5.1 repository of alik. When alik does a push these changes will be propagated to the main repository and, within 24 hours after the push, to the public repository.
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ChangeSet@1.2600, 2007-10-17 10:05:50+04:00, anozdrin@station. +7 -0   Patch for BUG#31111: --read-only crashes MySQL (events fail to load).   

  There actually were several problems here:

• WRITE-lock is required to load events from the mysql.event table, but in the read-only mode an ordinary user can not acquire it;
• Security_context::master_access attribute was not properly initialized in Security_context::init(), which led to differences in behavior with and without debug configure options.
• if the server failed to load events from mysql.event, it:
  • forgot to close the mysql.event table, that led to the coredump, described in the bug report;
  • did not deinitialize the replication module, that lead to memory-lost warning on exit.

  The patch is to fix all these problems:

• Use the super-user to acquire WRITE-lock on the mysql.even table;
• The WRITE-lock is acquired by the event scheduler in two cases:
  • on initial loading of events from the database;
  • when an event has been executed, so its attributes should be updated. Other cases when WRITE-lock is needed for the mysql.event table happen under the user account. So, nothing should be changed there: The user is able to create/update/drop an event only if he is a super-user.
• Initialize Security_context::master_access;
• Close the mysql.event table in case something went wrong;
• Deinitialize the replication module on exit.

  mysql-test/r/bug31111.result@1.1, 2007-10-17 10:05:48+04:00, anozdrin@station. +53 -0     Result file.

  mysql-test/r/bug31111.result@1.0, 2007-10-17 10:05:48+04:00, anozdrin@station. +0 -0

  mysql-test/t/bug31111-master.opt@1.1, 2007-10-17 10:05:48+04:00, anozdrin@station. +1 -0     A test case for BUG#31111.

  mysql-test/t/bug31111-master.opt@1.0, 2007-10-17 10:05:48+04:00, anozdrin@station. +0 -0

  mysql-test/t/bug31111.test@1.1, 2007-10-17 10:05:48+04:00, anozdrin@station. +101 -0     A test case for BUG#31111.

  mysql-test/t/bug31111.test@1.0, 2007-10-17 10:05:48+04:00, anozdrin@station. +0 -0

  sql/event_db_repository.cc@1.37, 2007-10-17 10:05:48+04:00, anozdrin@station. +23 -3

1. Close tables if something went wrong in simple_open_n_lock_tables();
2. Open the mysql.event table as the super user to be able to acquire WRITE-lock in the read-only mode.

  sql/events.cc@1.85, 2007-10-17 10:05:48+04:00, anozdrin@station. +15 -1     Open the mysql.event table as the super user to be able to acquire     WRITE-lock in the read-only mode.

  sql/mysqld.cc@1.670, 2007-10-17 10:05:48+04:00, anozdrin@station. +3 -0     If something went wrong with event loading, we the replication     module should be deinitialized prior to general exit procedure.

  sql/sql_class.cc@1.351, 2007-10-17 10:05:48+04:00, anozdrin@station. +1 -0     Initialize Security_context::master_acces.

diff -Nrup a/mysql-test/r/bug31111.result b/mysql-test/r/bug31111.result

--- /dev/null	Wed Dec 31 16:00:00 196900

+++ b/mysql-test/r/bug31111.result	2007-10-17 10:05:48 +04:00

@@ -0,0 +1,53 @@
+SELECT @@global.read_only;
+@@global.read_only
+1
+
+GRANT EVENT ON *.* TO u1@localhost;
+
+#
+# Connection: con1 (u1@localhost/test).
+#
+
+CREATE EVENT e1 ON SCHEDULE AT '2020-01-01 00:00:00' DO SET @a = 1;
+ERROR HY000: The MySQL server is running with the --read-only option so it cannot execute this statement
+
+ALTER EVENT e1 COMMENT 'comment';
+ERROR HY000: The MySQL server is running with the --read-only option so it cannot execute this statement
+
+DROP EVENT e1;
+ERROR HY000: The MySQL server is running with the --read-only option so it cannot execute this statement
+
+#
+# Connection: default.
+#
+
+CREATE EVENT e1 ON SCHEDULE AT '2020-01-01 00:00:00' DO SET @a = 1;
+
+ALTER EVENT e1 COMMENT 'comment';
+
+DROP EVENT e1;
+
+CREATE EVENT e1 ON SCHEDULE AT CURRENT_TIMESTAMP + INTERVAL 1 SECOND DO SET @a = 1;
+CREATE EVENT e2 ON SCHEDULE EVERY 1 SECOND DO SET @a = 1;
+
+SELECT name, last_executed IS NULL FROM mysql.event;
+name last_executed IS NULL
+e1 1
+e2 1
+
+SET GLOBAL EVENT_SCHEDULER = ON;
+
+# Sleeping for 3 seconds...
+
+SELECT name, last_executed IS NULL FROM mysql.event;
+name last_executed IS NULL
+e2 0
+
+SET GLOBAL EVENT_SCHEDULER = OFF;
+
+DROP EVENT e1;
+ERROR HY000: Unknown event 'e1'
+
+DROP EVENT e2;
+
+# That is it.

diff -Nrup a/mysql-test/t/bug31111-master.opt b/mysql-test/t/bug31111-master.opt

--- /dev/null	Wed Dec 31 16:00:00 196900

+++ b/mysql-test/t/bug31111-master.opt	2007-10-17 10:05:48 +04:00

@@ -0,0 +1 @@
+--read-only

diff -Nrup a/mysql-test/t/bug31111.test b/mysql-test/t/bug31111.test

--- /dev/null	Wed Dec 31 16:00:00 196900

+++ b/mysql-test/t/bug31111.test	2007-10-17 10:05:48 +04:00

@@ -0,0 +1,101 @@
+#
+# BUG#31111: --read-only crashes MySQL (events fail to load).
+#
+# It actually does not matter what SQL statements are here. The thing is being
+# tested is that the server is able to start.
+#
+
+SELECT @@global.read_only;
+
+--echo
+
+# Check that an ordinary user can not create/update/drop events.
+
+GRANT EVENT ON *.* TO u1@localhost;
+
+--echo
+
+--echo #
+--echo # Connection: con1 (u1@localhost/test).
+--echo #
+
+--connect(con1,localhost,u1,,test)
+
+--echo
+
+--error ER_OPTION_PREVENTS_STATEMENT
+CREATE EVENT e1 ON SCHEDULE AT '2020-01-01 00:00:00' DO SET @a = 1;
+
+--echo
+
+--error ER_OPTION_PREVENTS_STATEMENT
+ALTER EVENT e1 COMMENT 'comment';
+
+--echo
+
+--error ER_OPTION_PREVENTS_STATEMENT
+DROP EVENT e1;
+
+--echo
+
+--disconnect con1
+
+--echo #
+--echo # Connection: default.
+--echo #
+
+--connection default
+
+# Check that the super user still can create/update/drop events.
+
+--echo
+
+CREATE EVENT e1 ON SCHEDULE AT '2020-01-01 00:00:00' DO SET @a = 1;
+
+--echo
+
+ALTER EVENT e1 COMMENT 'comment';
+
+--echo
+
+DROP EVENT e1;
+
+--echo
+
+# Check that the scheduler is able to update event.
+
+CREATE EVENT e1 ON SCHEDULE AT CURRENT_TIMESTAMP + INTERVAL 1 SECOND DO SET @a = 1;
+CREATE EVENT e2 ON SCHEDULE EVERY 1 SECOND DO SET @a = 1;
+
+--echo
+
+SELECT name, last_executed IS NULL FROM mysql.event;
+
+--echo
+
+SET GLOBAL EVENT_SCHEDULER = ON;
+
+--echo
+
+--echo # Sleeping for 3 seconds...
+--sleep 3
+
+--echo
+
+SELECT name, last_executed IS NULL FROM mysql.event;
+
+--echo
+
+SET GLOBAL EVENT_SCHEDULER = OFF;
+
+--echo
+
+--error ER_EVENT_DOES_NOT_EXIST
+DROP EVENT e1;
+
+--echo
+
+DROP EVENT e2;
+
+--echo
+--echo # That is it.

diff -Nrup a/sql/event_db_repository.cc b/sql/event_db_repository.cc

--- a/sql/event_db_repository.cc	2007-08-25 12:43:10 +04:00

+++ b/sql/event_db_repository.cc	2007-10-17 10:05:48 +04:00

@@ -525,6 +525,9 @@ Event_db_repository::fill_schema_events(

• whether this open mode would work under LOCK TABLES, or inside a stored function or trigger.

+ Note, if the table can not be open, this operation will clean out all
+ table-related objects from the memory.
+

   @param[in]  thd  Thread context
   @param[in]  lock_type  How to lock the table
   @param[out] table  We will store the open table here

@@ -544,7 +547,10 @@ Event_db_repository::open_event_table(TH

   tables.init_one_table("mysql", "event", lock_type);  

   if (simple_open_n_lock_tables(thd, &tables))
+ {
+ close_thread_tables(thd, FALSE, FALSE);

     DBUG_RETURN(TRUE);
+ }
 

   *table= tables.table;
   tables.table->use_all_columns();
@@ -984,7 +990,8 @@ update_timing_fields_for_event(THD *thd,  {
   TABLE *table= NULL;
   Field **fields;
- int ret= 1;
+ bool ret= TRUE;
+ ulong saved_master_access;
 

   DBUG_ENTER("Event_db_repository::update_timing_fields_for_event");  

@@ -995,7 +1002,20 @@ update_timing_fields_for_event(THD *thd,
   if (thd->current_stmt_binlog_row_based)
     thd->clear_current_stmt_binlog_row_based();
 

• if (open_event_table(thd, TL_WRITE, &table))
  + /*
  + NOTE: even if we run in read-only mode, we should be able to lock the
  + mysql.event table for writing. In order to achieve this, we should call
  + mysql_lock_tables() under the super user.
  + */
  +
  + saved_master_access= thd->security_ctx->master_access;
  + thd->security_ctx->master_access |= SUPER_ACL;
  +
  + ret= open_event_table(thd, TL_WRITE, &table);
  +
  + thd->security_ctx->master_access= saved_master_access;
  +
  + if (ret)
  goto end;

   fields= table->field;
@@ -1028,7 +1048,7 @@ update_timing_fields_for_event(THD *thd,

     goto end;
   }  

• ret= 0;
  + ret= FALSE;
  

 end:
   if (table)
diff -Nrup a/sql/events.cc b/sql/events.cc

--- a/sql/events.cc	2007-08-15 19:08:40 +04:00

+++ b/sql/events.cc	2007-10-17 10:05:48 +04:00

@@ -1124,11 +1124,25 @@ Events::load_events_from_db(THD *thd)

   READ_RECORD read_record_info;
   bool ret= TRUE;
   uint count= 0;
+ ulong saved_master_access;
 

   DBUG_ENTER("Events::load_events_from_db");    DBUG_PRINT("enter", ("thd: 0x%lx", (long) thd));  

• if (db_repository->open_event_table(thd, TL_WRITE, &table))
  + /*
  + NOTE: even if we run in read-only mode, we should be able to lock the
  + mysql.event table for writing. In order to achieve this, we should call
  + mysql_lock_tables() under the super user.
  + */
  +
  + saved_master_access= thd->security_ctx->master_access;
  + thd->security_ctx->master_access |= SUPER_ACL;
  +
  + ret= db_repository->open_event_table(thd, TL_WRITE, &table);
  +
  + thd->security_ctx->master_access= saved_master_access;
  +
  + if (ret)
  { sql_print_error("Event Scheduler: Failed to open table mysql.event"); DBUG_RETURN(TRUE); diff -Nrup a/sql/mysqld.cc b/sql/mysqld.cc --- a/sql/mysqld.cc 2007-08-28 11:02:53 +04:00
  +++ b/sql/mysqld.cc 2007-10-17 10:05:48 +04:00
  @@ -3930,7 +3930,10 @@ we force server id to 2, but this MySQL create_maintenance_thread();

   if (Events::init(opt_noacl))
+ {
+ end_slave();

     unireg_abort(1);
+ }
 

   sql_print_information(ER(ER_STARTUP),my_progname,server_version,

                         ((unix_sock == INVALID_SOCKET) ? (char*) ""
diff -Nrup a/sql/sql_class.cc b/sql/sql_class.cc
--- a/sql/sql_class.cc	2007-10-15 16:42:39 +04:00

+++ b/sql/sql_class.cc	2007-10-17 10:05:48 +04:00

@@ -2404,6 +2404,7 @@ void Security_context::init()

   host= user= priv_user= ip= 0;
   host_or_ip= "connecting host";
   priv_host[0]= '\0';
+ master_access= 0;

 #ifndef NO_EMBEDDED_ACCESS_CHECKS
   db_access= NO_ACCESS;
 #endif

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Received on Wed Oct 17 02:05:08 2007