MDEV-39609 - SIGSEGV in process_i_s_table_temporary_tables after failed ALTER TABLE on temporary TIMESTAMP table with CHECK constraint

Problem:
SELECT * FROM information_schema.tables (and SHOW TABLES) crashed with a SIGSEGV in process_i_s_table_temporary_tables() after a failed strict-mode ALTER TABLE on a TEMPORARY table with a zero-default TIMESTAMP column and a CHECK constraint.

Cause:
The failed ALTER marks the temp table needs_reopen. On reopen, Sql_mode_save_for_frm_handling relaxed only parser flags, not the strict/zero-date ones, so evaluating the stored zero TIMESTAMP default was escalated to ER_WRONG_VALUE. open_temporary_table() then failed, leaving the TMP_TABLE_SHARE in temporary_tables with an empty all_tmp_tables. The I_S iteration walked into that empty share and dereferenced a NULL TABLE. Regression in 11.4.

Fix:
Broadened Sql_mode_save_for_frm_handling to also clear MODE_STRICT_TRANS_TABLES, MODE_STRICT_ALL_TABLES, MODE_NO_ZERO_DATE, and MODE_NO_ZERO_IN_DATE while parsing FRM-stored defaults/expressions. Reopening an already-validated temp table now succeeds in any sql_mode, so the empty share is never created and the crash is gone; strictness still applies when new values are written.

Author: mariadb-PranavTiwari

mysql-test/main/reopen_temp_table.result

@@ -243,3 +243,31 @@ f	b
 NULL	1
 NULL	2
 drop table t1;
+#
+# Start of 11.4 tests
+#
+#
+# MDEV-39609 - SIGSEGV in process_i_s_table_temporary_tables after failed ALTER TABLE on temporary TIMESTAMP table with CHECK constraint
+#
+CREATE TEMPORARY TABLE t (c INT KEY) ENGINE=INNODB;
+ALTER TABLE t MODIFY c TIMESTAMP;
+ALTER TABLE t ADD CHECK(c=0);
+ALTER TABLE t ADD INDEX idx1 (c);
+SET SESSION sql_mode='TRADITIONAL';
+ALTER TABLE t ROW_FORMAT=COMPRESSED;
+ERROR HY000: InnoDB refuses to write tables with ROW_FORMAT=COMPRESSED or KEY_BLOCK_SIZE.
+ALTER TABLE t ANALYZE PARTITION p2;
+ERROR HY000: Partition management on a not partitioned table is not possible
+SELECT table_schema, table_name, table_type, engine, temporary
+FROM information_schema.tables WHERE table_name='t';
+table_schema	table_name	table_type	engine	temporary
+test	t	TEMPORARY	InnoDB	Y
+INSERT INTO t VALUES (0);
+ERROR 22007: Incorrect datetime value: '0' for column `test`.`t`.`c` at row 1
+INSERT INTO t VALUES ('0000-00-00 00:00:00');
+ERROR 22007: Incorrect datetime value: '0000-00-00 00:00:00' for column `test`.`t`.`c` at row 1
+SET SESSION sql_mode=DEFAULT;
+DROP TEMPORARY TABLE t;
+#
+# End of 11.4 tests
+#

mysql-test/main/reopen_temp_table.test

@@ -226,3 +226,37 @@ alter table t1 change if exists a b int, algorithm=inplace;
 check table t1;
 select * from t1;
 drop table t1;
+
+--echo #
+--echo # Start of 11.4 tests
+--echo #
+
+--echo #
+--echo # MDEV-39609 - SIGSEGV in process_i_s_table_temporary_tables after failed ALTER TABLE on temporary TIMESTAMP table with CHECK constraint
+--echo #
+
+CREATE TEMPORARY TABLE t (c INT KEY) ENGINE=INNODB;
+ALTER TABLE t MODIFY c TIMESTAMP;
+ALTER TABLE t ADD CHECK(c=0);
+ALTER TABLE t ADD INDEX idx1 (c);
+SET SESSION sql_mode='TRADITIONAL';
+
+--error ER_UNSUPPORTED_COMPRESSED_TABLE
+ALTER TABLE t ROW_FORMAT=COMPRESSED;
+--error ER_PARTITION_MGMT_ON_NONPARTITIONED
+ALTER TABLE t ANALYZE PARTITION p2;
+
+SELECT table_schema, table_name, table_type, engine, temporary
+FROM information_schema.tables WHERE table_name='t';
+
+--error ER_TRUNCATED_WRONG_VALUE
+INSERT INTO t VALUES (0);
+--error ER_TRUNCATED_WRONG_VALUE
+INSERT INTO t VALUES ('0000-00-00 00:00:00');
+
+SET SESSION sql_mode=DEFAULT;
+DROP TEMPORARY TABLE t;
+
+--echo #
+--echo # End of 11.4 tests
+--echo #

sql/sql_class.h

@@ -8168,10 +8168,23 @@ class Sql_mode_save_for_frm_handling: public Sql_mode_save
       ? MODE_NO_AUTO_VALUE_ON_ZERO    affect UPDATEs
       + MODE_NO_BACKSLASH_ESCAPES     affect expression parsing
       + MODE_EMPTY_STRING_IS_NULL     affect expression parsing
+      + MODE_STRICT_TRANS_TABLES      affect stored default/expr validation
+      + MODE_STRICT_ALL_TABLES        affect stored default/expr validation
+      + MODE_NO_ZERO_DATE             affect stored default/expr validation
+      + MODE_NO_ZERO_IN_DATE          affect stored default/expr validation
+
+      The last four affect execution, not parsing, but must also be switched
+      off here: re-evaluating already-validated FRM defaults/CHECK expressions
+      when reopening a table (e.g. after a failed ALTER) must not turn a stored
+      zero DATE/TIMESTAMP into ER_WRONG_VALUE. Strictness applies only to newly
+      written values.
     */
     thd->variables.sql_mode&= ~(MODE_PIPES_AS_CONCAT | MODE_ANSI_QUOTES |
                                 MODE_IGNORE_SPACE | MODE_NO_BACKSLASH_ESCAPES |
-                                MODE_ORACLE | MODE_EMPTY_STRING_IS_NULL);
+                                MODE_ORACLE | MODE_EMPTY_STRING_IS_NULL |
+                                MODE_STRICT_TRANS_TABLES | MODE_STRICT_ALL_TABLES |
+                                MODE_NO_ZERO_DATE | MODE_NO_ZERO_IN_DATE);
+
   };
 
   ~Sql_mode_save_for_frm_handling()