From af31e2c55d569de343b2b855131e73c0138e7c2d Mon Sep 17 00:00:00 2001
From: Monty <monty@mariadb.org>
Date: Sun, 14 Feb 2021 17:42:19 +0200
Subject: [PATCH] MDEV-23843 Assertions in Diagnostics_area upon table
 operations under FTWRL

2 different problems:
- MYSQL_BIN_LOG::write() did not check if mdl_context.acquire_lock() failed
- Sql_cmd_optimize_table::execute() and Sql_cmd_repair_table::execute()
  called write_bin_log(), which could fail if sql_admin() had already
  called my_eof()

Fixed by adding check for aquire_lock() return status and protect
write_bin_log() in the above two functions with set_overwrite_status().
---
 mysql-test/main/flush_and_binlog.result | 22 +++++++++++++++++++
 mysql-test/main/flush_and_binlog.test   | 29 +++++++++++++++++++++++++
 sql/log.cc                              |  5 +++--
 sql/sql_admin.cc                        |  4 ++++
 4 files changed, 58 insertions(+), 2 deletions(-)
 create mode 100644 mysql-test/main/flush_and_binlog.result
 create mode 100644 mysql-test/main/flush_and_binlog.test

diff --git a/mysql-test/main/flush_and_binlog.result b/mysql-test/main/flush_and_binlog.result
new file mode 100644
index 00000000000..b9560964046
--- /dev/null
+++ b/mysql-test/main/flush_and_binlog.result
@@ -0,0 +1,22 @@
+#
+# MDEV-23843 Assertions in Diagnostics_area upon table operations under
+# FTWRL
+#
+CREATE TABLE t1 (a INT);
+FLUSH TABLES WITH READ LOCK;
+connect  con1,localhost,root,,;
+SET lock_wait_timeout= 1;
+OPTIMIZE TABLE t1;
+ERROR HY000: Lock wait timeout exceeded; try restarting transaction
+disconnect con1;
+connection default;
+UNLOCK TABLES;
+DROP TABLE t1;
+FLUSH TABLES WITH READ LOCK;
+connect  con1,localhost,root,,test;
+SET lock_wait_timeout= 1;
+FLUSH TABLES;
+ERROR HY000: Lock wait timeout exceeded; try restarting transaction
+connection default;
+disconnect con1;
+unlock tables;
diff --git a/mysql-test/main/flush_and_binlog.test b/mysql-test/main/flush_and_binlog.test
new file mode 100644
index 00000000000..373b900b451
--- /dev/null
+++ b/mysql-test/main/flush_and_binlog.test
@@ -0,0 +1,29 @@
+--source include/have_log_bin.inc
+
+--echo #
+--echo # MDEV-23843 Assertions in Diagnostics_area upon table operations under
+--echo # FTWRL
+--echo #
+
+CREATE TABLE t1 (a INT);
+FLUSH TABLES WITH READ LOCK;
+--connect (con1,localhost,root,,)
+SET lock_wait_timeout= 1;
+--error ER_LOCK_WAIT_TIMEOUT
+OPTIMIZE TABLE t1;
+# Cleanup
+--disconnect con1
+--connection default
+UNLOCK TABLES;
+DROP TABLE t1;
+#
+# Second test case from MDEV_23843
+#
+FLUSH TABLES WITH READ LOCK;
+--connect (con1,localhost,root,,test)
+SET lock_wait_timeout= 1;
+--error ER_LOCK_WAIT_TIMEOUT
+FLUSH TABLES;
+--connection default
+--disconnect con1
+unlock tables;
diff --git a/sql/log.cc b/sql/log.cc
index 480e3b696cc..2a1142d8391 100644
--- a/sql/log.cc
+++ b/sql/log.cc
@@ -6390,8 +6390,9 @@ bool MYSQL_BIN_LOG::write(Log_event *event_info, my_bool *with_annotate)
       DBUG_ASSERT(!thd->backup_commit_lock);
 
       mdl_request.init(MDL_key::BACKUP, "", "", MDL_BACKUP_COMMIT, MDL_EXPLICIT);
-      thd->mdl_context.acquire_lock(&mdl_request,
-                                    thd->variables.lock_wait_timeout);
+      if (thd->mdl_context.acquire_lock(&mdl_request,
+                                        thd->variables.lock_wait_timeout))
+        DBUG_RETURN(1);
       thd->backup_commit_lock= &mdl_request;
 
       if ((res= thd->wait_for_prior_commit()))
diff --git a/sql/sql_admin.cc b/sql/sql_admin.cc
index 0a6e76d117f..c9185045315 100644
--- a/sql/sql_admin.cc
+++ b/sql/sql_admin.cc
@@ -1455,7 +1455,9 @@ bool Sql_cmd_optimize_table::execute(THD *thd)
     /*
       Presumably, OPTIMIZE and binlog writing doesn't require synchronization
     */
+    thd->get_stmt_da()->set_overwrite_status(true);
     res= write_bin_log(thd, TRUE, thd->query(), thd->query_length());
+    thd->get_stmt_da()->set_overwrite_status(false);
   }
   m_lex->first_select_lex()->table_list.first= first_table;
   m_lex->query_tables= first_table;
@@ -1487,7 +1489,9 @@ bool Sql_cmd_repair_table::execute(THD *thd)
     /*
       Presumably, REPAIR and binlog writing doesn't require synchronization
     */
+    thd->get_stmt_da()->set_overwrite_status(true);
     res= write_bin_log(thd, TRUE, thd->query(), thd->query_length());
+    thd->get_stmt_da()->set_overwrite_status(false);
   }
   m_lex->first_select_lex()->table_list.first= first_table;
   m_lex->query_tables= first_table;