MDEV-22134: handle_fatal_signal (sig=11) in __strlen_avx2 on START SLAVE |...

MDEV-22134: handle_fatal_signal (sig=11) in __strlen_avx2 on START SLAVE | Assertion `global_system_variables.session_track_system_variables' failed in Session_sysvars_tracker::init | *** buffer overflow detected *** (on optimized builds)

Prohibit assigning NULL as for other system variables.

mysql-test/main/mysqltest_tracking_info.result

@@ -45,3 +45,15 @@ Warning	1681	'engine_condition_pushdown=on' is deprecated and will be removed in
 set @@optimizer_switch=@save_optimizer_switch;
 SET @@session.session_track_system_variables= @save_session_track_system_variables;
 # End of 10.2 tests
+#
+# MDEV-22134 handle_fatal_signal (sig=11) in __strlen_avx2 on START
+# SLAVE | Assertion
+# `global_system_variables.session_track_system_variables' failed in
+# Session_sysvars_tracker::init | *** buffer overflow detected ***
+# (on optimized builds)
+#
+SET @@GLOBAL.session_track_system_variables=NULL;
+ERROR 42000: Variable 'session_track_system_variables' can't be set to the value of 'NULL'
+SET SESSION session_track_system_variables=NULL;
+ERROR 42000: Variable 'session_track_system_variables' can't be set to the value of 'NULL'
+# End of 10.3 tests

mysql-test/main/mysqltest_tracking_info.test

@@ -45,3 +45,18 @@ set @@optimizer_switch=@save_optimizer_switch;
 SET @@session.session_track_system_variables= @save_session_track_system_variables;
 
 --echo # End of 10.2 tests
+
+--echo #
+--echo # MDEV-22134 handle_fatal_signal (sig=11) in __strlen_avx2 on START
+--echo # SLAVE | Assertion
+--echo # `global_system_variables.session_track_system_variables' failed in
+--echo # Session_sysvars_tracker::init | *** buffer overflow detected ***
+--echo # (on optimized builds)
+--echo #
+
+--error ER_WRONG_VALUE_FOR_VAR
+SET @@GLOBAL.session_track_system_variables=NULL;
+--error ER_WRONG_VALUE_FOR_VAR
+SET SESSION session_track_system_variables=NULL;
+
+--echo # End of 10.3 tests

mysql-test/suite/sys_vars/r/session_track_system_variables_basic.result

@@ -110,15 +110,9 @@ autocommit,character_set_client,character_set_connection,character_set_results,t
 connection default;
 # Testing NULL
 SET @@global.session_track_system_variables = NULL;
+ERROR 42000: Variable 'session_track_system_variables' can't be set to the value of 'NULL'
 SET @@session.session_track_system_variables = NULL;
-# Global - expect "" instead of NULL
-SELECT @@global.session_track_system_variables;
-@@global.session_track_system_variables
-NULL
-# Session - expect "" instead of NULL
-SELECT @@session.session_track_system_variables;
-@@session.session_track_system_variables
-
+ERROR 42000: Variable 'session_track_system_variables' can't be set to the value of 'NULL'
 # testing with duplicate entries.
 SET @@global.session_track_system_variables= "time_zone";
 SET @@session.session_track_system_variables= "time_zone";

mysql-test/suite/sys_vars/t/session_track_system_variables_basic.test

@@ -85,14 +85,11 @@ SELECT @@session.session_track_system_variables;
 connection default;
 
 --echo # Testing NULL
+--error ER_WRONG_VALUE_FOR_VAR
 SET @@global.session_track_system_variables = NULL;
+--error ER_WRONG_VALUE_FOR_VAR
 SET @@session.session_track_system_variables = NULL;
 
---echo # Global - expect "" instead of NULL
-SELECT @@global.session_track_system_variables;
---echo # Session - expect "" instead of NULL
-SELECT @@session.session_track_system_variables;
-
 --echo # testing with duplicate entries.
 # Lets first set it to some valid value.
 SET @@global.session_track_system_variables= "time_zone";

sql/session_tracker.cc

@@ -189,7 +189,13 @@ bool sysvartrack_validate_value(THD *thd, const char *str, size_t len)
   char *token, *lasts= NULL;
   size_t rest= var_list.length;
 
-  if (!var_list.str || var_list.length == 0 ||
+  if (!var_list.str)
+  {
+    my_error(ER_WRONG_VALUE_FOR_VAR, MYF(0),
+             "session_track_system_variables", "NULL");
+    return false;
+  }
+  if (var_list.length == 0 ||
       !strcmp(var_list.str, "*"))
   {
     return false;