Bug#26174 Server Crash:INSERT ... SELECT ... FROM I_S.GLOBAL_STATUS in Event

- Some variables in I_S.GLOBAL_STATUS were depending on a network
  connection in order to evaluate. Since no network connection is 
  present during the execution of an event, this caused the server
  to crash.
- The variable function hooks does now verify that the vio-
  object is valid before attempting to use it.


mysql-test/r/information_schema.result:
  Added test case.
mysql-test/t/information_schema.test:
  Added test case.

mysql-test/r/information_schema.result

@@ -1408,4 +1408,32 @@ select user,db from information_schema.processlist;
 user	db
 user3148	test
 drop user user3148@localhost;
+DROP TABLE IF EXISTS thread_status;
+CREATE TABLE thread_status (variable_name VARCHAR(64),
+variable_value DECIMAL(22,7));
+CREATE TABLE server_status (variable_name VARCHAR(64),
+variable_value DECIMAL(22,7));
+DROP EVENT IF EXISTS log_status;
+CREATE EVENT log_status
+ON SCHEDULE EVERY 1 SECOND
+DO
+BEGIN
+INSERT INTO thread_status SELECT variable_name, variable_value FROM
+information_schema.session_status;
+INSERT INTO server_status SELECT variable_name, variable_value FROM
+information_schema.global_status;
+END$$
+SET GLOBAL event_scheduler=1;
+SELECT * FROM thread_status WHERE variable_name LIKE 'SSL%' LIMIT 1,2;
+variable_name	variable_value
+SSL_ACCEPTS	0.0000000
+SSL_CALLBACK_CACHE_HITS	0.0000000
+SELECT variable_name FROM server_status LIMIT 1,2;
+variable_name
+ABORTED_CONNECTS
+BINLOG_CACHE_DISK_USE
+DROP EVENT log_status;
+DROP TABLE thread_status;
+DROP TABLE server_status;
+SET GLOBAL event_scheduler=0;
 End of 5.1 tests.

mysql-test/t/information_schema.test

@@ -1042,5 +1042,45 @@ select user,db from information_schema.processlist;
 connection default;
 drop user user3148@localhost;
 
+
+
+#
+# Bug #26174 Server Crash: INSERT ... SELECT ... FROM I_S.GLOBAL_STATUS in Event
+#
+--disable_warnings
+DROP TABLE IF EXISTS thread_status;
+CREATE TABLE thread_status (variable_name VARCHAR(64),
+variable_value DECIMAL(22,7));
+CREATE TABLE server_status (variable_name VARCHAR(64),
+variable_value DECIMAL(22,7));
+DROP EVENT IF EXISTS log_status;
+--enable_warnings
+
+DELIMITER $$;
+
+CREATE EVENT log_status
+ ON SCHEDULE EVERY 1 SECOND
+ DO
+ BEGIN
+  INSERT INTO thread_status SELECT variable_name, variable_value FROM
+information_schema.session_status;
+  INSERT INTO server_status SELECT variable_name, variable_value FROM
+information_schema.global_status;
+ END$$
+
+DELIMITER ;$$
+
+SET GLOBAL event_scheduler=1;
+sleep 1;
+SELECT * FROM thread_status WHERE variable_name LIKE 'SSL%' LIMIT 1,2;
+SELECT variable_name FROM server_status LIMIT 1,2;
+
+
+
+DROP EVENT log_status;
+DROP TABLE thread_status;
+DROP TABLE server_status;
+SET GLOBAL event_scheduler=0;
+
 --echo End of 5.1 tests.
 

sql/mysqld.cc

@@ -3803,6 +3803,8 @@ we force server id to 2, but this MySQL server will not act as a slave.");
   {
     if (Events::get_instance()->init())
       unireg_abort(1);
+  } else {
+    Events::opt_event_scheduler= Events::EVENTS_DISABLED;
   }
 
   /* Signal threads waiting for server to be started */
@@ -6662,12 +6664,20 @@ static int show_ssl_ctx_get_session_cache_mode(THD *thd, SHOW_VAR *var, char *bu
   return 0;
 }
 
-/* Functions relying on SSL */
+/*
+   Functions relying on SSL 
+   Note: In the show_ssl_* functions, we need to check if we have a
+         valid vio-object since this isn't always true, specifically
+         when session_status or global_status is requested from
+         inside an Event.
+ */
 static int show_ssl_get_version(THD *thd, SHOW_VAR *var, char *buff)
 {
   var->type= SHOW_CHAR;
-  var->value= const_cast<char*>(thd->net.vio->ssl_arg ?
-        SSL_get_version((SSL*) thd->net.vio->ssl_arg) : "");
+  if( thd->vio_ok() && thd->net.vio->ssl_arg )
+    var->value= const_cast<char*>(SSL_get_version((SSL*) thd->net.vio->ssl_arg));
+  else
+    var->value= "";
   return 0;
 }
 
@@ -6675,9 +6685,10 @@ static int show_ssl_session_reused(THD *thd, SHOW_VAR *var, char *buff)
 {
   var->type= SHOW_LONG;
   var->value= buff;
-  *((long *)buff)= (long)thd->net.vio->ssl_arg ?
-                         SSL_session_reused((SSL*) thd->net.vio->ssl_arg) :
-                         0;
+  if( thd->vio_ok() && thd->net.vio->ssl_arg )
+    *((long *)buff)= (long)SSL_session_reused((SSL*) thd->net.vio->ssl_arg);
+  else
+    *((long *)buff)= 0;
   return 0;
 }
 
@@ -6685,9 +6696,10 @@ static int show_ssl_get_default_timeout(THD *thd, SHOW_VAR *var, char *buff)
 {
   var->type= SHOW_LONG;
   var->value= buff;
-  *((long *)buff)= (long)thd->net.vio->ssl_arg ?
-                         SSL_get_default_timeout((SSL*)thd->net.vio->ssl_arg) :
-                         0;
+  if( thd->vio_ok() && thd->net.vio->ssl_arg )
+    *((long *)buff)= (long)SSL_get_default_timeout((SSL*)thd->net.vio->ssl_arg);
+  else
+    *((long *)buff)= 0;
   return 0;
 }
 
@@ -6695,9 +6707,10 @@ static int show_ssl_get_verify_mode(THD *thd, SHOW_VAR *var, char *buff)
 {
   var->type= SHOW_LONG;
   var->value= buff;
-  *((long *)buff)= (long)thd->net.vio->ssl_arg ?
-                         SSL_get_verify_mode((SSL*)thd->net.vio->ssl_arg) :
-                         0;
+  if( thd->net.vio && thd->net.vio->ssl_arg )
+    *((long *)buff)= (long)SSL_get_verify_mode((SSL*)thd->net.vio->ssl_arg);
+  else
+    *((long *)buff)= 0;
   return 0;
 }
 
@@ -6705,17 +6718,20 @@ static int show_ssl_get_verify_depth(THD *thd, SHOW_VAR *var, char *buff)
 {
   var->type= SHOW_LONG;
   var->value= buff;
-  *((long *)buff)= (long)thd->net.vio->ssl_arg ?
-                         SSL_get_verify_depth((SSL*)thd->net.vio->ssl_arg) :
-                         0;
+  if( thd->vio_ok() && thd->net.vio->ssl_arg )
+    *((long *)buff)= (long)SSL_get_verify_depth((SSL*)thd->net.vio->ssl_arg);
+  else
+    *((long *)buff)= 0;
   return 0;
 }
 
 static int show_ssl_get_cipher(THD *thd, SHOW_VAR *var, char *buff)
 {
   var->type= SHOW_CHAR;
-  var->value= const_cast<char*>(thd->net.vio->ssl_arg ?
-              SSL_get_cipher((SSL*) thd->net.vio->ssl_arg) : "");
+  if( thd->vio_ok() && thd->net.vio->ssl_arg )
+    var->value= const_cast<char*>(SSL_get_cipher((SSL*) thd->net.vio->ssl_arg));
+  else
+    var->value= "";
   return 0;
 }
 
@@ -6723,7 +6739,7 @@ static int show_ssl_get_cipher_list(THD *thd, SHOW_VAR *var, char *buff)
 {
   var->type= SHOW_CHAR;
   var->value= buff;
-  if (thd->net.vio->ssl_arg)
+  if (thd->vio_ok() && thd->net.vio->ssl_arg)
   {
     int i;
     const char *p;

sql/set_var.cc

@@ -4000,7 +4000,7 @@ sys_var_event_scheduler::update(THD *thd, set_var *var)
   DBUG_ENTER("sys_var_event_scheduler::update");
   if (Events::opt_event_scheduler == Events::EVENTS_DISABLED)
   {
-    my_error(ER_OPTION_PREVENTS_STATEMENT, MYF(0), "--event-scheduler=DISABLED");
+    my_error(ER_OPTION_PREVENTS_STATEMENT, MYF(0), "--event-scheduler=DISABLED or --skip-grant-tables");
     DBUG_RETURN(TRUE);
   }