(Variant #2 of the patch, which keeps the sp_head object inside the
MEM_ROOT that sp_head object owns)
(10.3 requires extra work due to sp_package, will commit a separate
patch for it)

sp_head::operator new() and operator delete() were dereferencing sp_head*
pointers to memory that didn't hold a valid sp_head object (it was
not created/already destroyed).
This caused UBSan to crash when looking up type information.

Fixed by providing static sp_head::create() and sp_head::destroy() methods.

Problem:
========
SHOW BINLOG EVENTS FROM <pos> reports following ASAN error.

AddressSanitizer: heap-buffer-overflow on address
READ of size 1 at 0x60e00009cf71 thread T28
#0 0x55e37e034ae2 in net_field_length

Fix:
===
**Part10: Avoid reading out of buffer**

Problem:
========
SHOW BINLOG EVENTS FROM <pos> reports following assert when ASAN is enabled.

Query_log_event::Query_log_event(const char*, uint,
    const Format_description_log_event*, Log_event_type):
  Assertion `(pos) + (6) <= (end)' failed

Fix:
===
**Part9: Removed additional DBUG_ASSERT**

Problem:
========
SHOW BINLOG EVENTS FROM <pos> reports following ASAN error

AddressSanitizer: SEGV on unknown address
The signal is caused by a READ memory access.
User_var_log_event::User_var_log_event(char const*, unsigned int,
    Format_description_log_event const*)

Implemented part of upstream patch.
commit: mysql/mysql-server@a3a497ccf7ecacc900551fb1e47ea4078b45c351

Fix:
===
**Part8: added checks to avoid reading out of buffer limits**

Problem:
========
SHOW BINLOG EVENTS FROM <pos> reports following ASAN error
"heap-buffer-overflow on address" and some times it asserts.

Table_map_log_event::Table_map_log_event(const char*, uint,
    const Format_description_log_event*)
Assertion `m_field_metadata_size <= (m_colcnt * 2)' failed.

Fix:
===
**Part7: Avoid reading out of buffer**


Converted debug assert to error handler code.

Problem:
========
SHOW BINLOG EVENTS FROM <pos> reports following ASAN error

AddressSanitizer: heap-buffer-overflow on address 0x60400002acb8
Load_log_event::copy_log_event(char const*, unsigned long, int,
    Format_description_log_event const*)

Fix:
===
**Part6: Moved the event_len validation to the begin of copy_log_event function**

Problem:
========
SHOW BINLOG EVENTS FROM <pos> reports following ASAN error

AddressSanitizer: heap-buffer-overflow on address
String::append(char const*, unsigned int)
Query_log_event::pack_info(Protocol*)

Fix:
===
**Part5: Added check to catch buffer overflow**

Problem:
========
SHOW BINLOG EVENTS FROM <pos> reports following ASAN error

heap-buffer-overflow within "my_strndup" in Rotate_log_event

my_strndup /mysys/my_malloc.c:254
Rotate_log_event::Rotate_log_event(char const*, unsigned int,
    Format_description_log_event const*)

Fix:
===
**Part4: Improved the check for event_len validation**

Problem:
========
SHOW BINLOG EVENTS FROM <pos> reports following crash when ASAN is enabled.

SEGV on unknown address
in inline_mysql_mutex_destroy
in my_bitmap_free
in Update_rows_log_event::~Update_rows_log_event()

Fix:
===
**Part3: Initialize m_cols_ai.bitmap to NULL**

Problem:
========
SHOW BINLOG EVENTS FROM <pos> reports following assert when ASAN is enabled.

Rows_log_event::Rows_log_event(const char*, uint,
    const Format_description_log_event*):
Assertion `var_header_len >= 2'

Implemented part of upstream patch.
commit: mysql/mysql-server@a3a497ccf7ecacc900551fb1e47ea4078b45c351

Fix:
===
**Part2: Avoid reading out of buffer limits**

Problem:
========
SHOW BINLOG EVENTS FROM <pos> causes a variety of failures, some of which are
listed below. It is not a race condition issue, but there is some
non-determinism in it.

Analysis:
========
"show binlog events from <pos>" code considers the user given position as a
valid event start position. The code starts reading data from this event start
position onwards and tries to map it to a set of known events. Each event has
a specific event structure and asserts have been added to ensure that read
event data satisfies the event specific requirements. When a random position
is supplied to "show binlog events command" the event structure specific
checks will fail and they result in assert.

Fix:
====
The fix is split into different parts. Each part addresses either an ASAN
issue or an assert/crash.

**Part1: Checksum based position validation when checksum is enabled**


Using checksum validate the very first event read at the user specified
position. If there is a checksum mismatch report an appropriate error for the
invalid event.

Moved to the next problematic year (2038).

For Item_direct_view_ref , get value from val_* methods
instead of result* family
The val_* methods gets value from the item on which it is referred.

MDEV-19680:: Assertion `!table || (!table->read_set || bitmap_is_set(table->read_set, field_index) || (!(ptr >= table->record[0] && ptr < table->record[0] + table->s->reclength)))' or alike failed upon SELECT with mix of functions from simple view

Set read_set bitmap for view from the JOIN::all_fields list instead of JOIN::fields_list
as split_sum_func would have added items to the all_fields list.

in 10.1+ one should use

MY_CHECK_AND_SET_COMPILER_FLAG("-Wno-address-of-packed-member")

and it's already done in storage/tokudb/PerconaFT/CMakeLists.txt

Item_ref::val_(datetime|time)_packed() erroneously called
(*ref)->val_(datetime|time)_packed().

- Fixing to call (*ref)->val_(datetime|time)_packed_result().
- Backporting Item::val_(datetime|time)_packed_result() from 10.3.
- Fixing Item_field::get_date_result() to handle null_value in the same
  way how Item_field::get_date() does.

do not fallback to malloc(), always return properly aligned buffer

One may not call memcpy(dst, src=NULL, size), even if size==0.

Remove Query_tables_list::lock_tables_state - it is not used and it causes
errors like this:

sql_lex.h:1675:7: runtime error: load of value 2779096485, which is not a
valid value for type 'enum_lock_tables_state'

Fix wrong typecast

Fixed the condition for waking up/creating another thread.

If there is some work to do (if the request queue is not empty),
a thread should be woken or created.

The condition was incorrect since 18c9b345

crashes on Debian 10

Problem:
=======
Test "binlog.binlog_parallel_replication_marks_row" fails sporadically due to
result length mismatch.

Analysis:
=========
Test generates a binary log and it looks for certain words within the binary
log file and prints them. For example word like "GTID,BEGIN,COMMIT ...".
Binary log output contains base64 encoded characters. Occasionally the encoded
characters match with the above words and results in test failure.

+XwoFWxMBAAAALgAAAGEDAAAAAB8AAAAAAAEABHRlc3QAAnQxAAIDAwACFGTIDQ==
+AAAAAAAAAAAEEwQADQgICAoKCgGTIDw9

Fix:
===
Improve the regular expression to match exact words.

Let MTR check for error existence after running a test and return it back to user.

Error reporting itset might be much better, but first of all we need to see that
something went wrong.

wsrep_on parameter can be visible even when wsrep_on is set OFF
so we need to check variable_value from I_S also.

Set an explicit start and stop timeout of 900 seconds for the
MariaDB Server systemd service

Set an explicit start and stop timeout of 900 seconds for the
MariaDB Server systemd service

It is C++, not Java, the order of includes is often important.

It is C++, not Java, the order of includes is often important.