ASAN errors in st_select_lex::print / With_element::print with optimizer trace on 2nd execution of PS

CREATE TABLE t (a INT);

INSERT INTO t VALUES (1),(2);

SET SESSION optimizer_trace = 'enabled=on';

PREPARE stmt FROM 'EXPLAIN EXTENDED WITH cte AS (SELECT CASE a WHEN 2 THEN 0 END AS f FROM t) SELECT * FROM cte';

EXECUTE stmt;

EXECUTE stmt;

# Cleanup

DROP TABLE t;

==1813883==ERROR: AddressSanitizer: use-after-poison on address 0x629000097340 at pc 0x562c3c9225b8 bp 0x7fbc220054c0 sp 0x7fbc220054b8

READ of size 8 at 0x629000097340 thread T5

    #0 0x562c3c9225b7 in st_select_lex::print(THD*, String*, enum_query_type) /data/src/10.7/sql/sql_select.cc:28482

    #1 0x562c3c71aade in st_select_lex_unit::print(String*, enum_query_type) /data/src/10.7/sql/sql_lex.cc:3729

    #2 0x562c3cd644e5 in With_element::print(THD*, String*, enum_query_type) /data/src/10.7/sql/sql_cte.cc:1701

    #3 0x562c3cd64b18 in With_clause::print(THD*, String*, enum_query_type) /data/src/10.7/sql/sql_cte.cc:1657

    #4 0x562c3c71aa3c in st_select_lex_unit::print(String*, enum_query_type) /data/src/10.7/sql/sql_lex.cc:3704

    #5 0x562c3c78c7d2 in execute_sqlcom_select /data/src/10.7/sql/sql_parse.cc:6218

    #6 0x562c3c7b444a in mysql_execute_command(THD*, bool) /data/src/10.7/sql/sql_parse.cc:3943

    #7 0x562c3c825ad9 in Prepared_statement::execute(String*, bool) /data/src/10.7/sql/sql_prepare.cc:5221

    #8 0x562c3c82634e in Prepared_statement::execute_loop(String*, bool, unsigned char*, unsigned char*) /data/src/10.7/sql/sql_prepare.cc:4644

    #9 0x562c3c827071 in mysql_sql_stmt_execute(THD*) /data/src/10.7/sql/sql_prepare.cc:3688

    #10 0x562c3c7b1475 in mysql_execute_command(THD*, bool) /data/src/10.7/sql/sql_parse.cc:3959

    #11 0x562c3c7b925a in mysql_parse(THD*, char*, unsigned int, Parser_state*) /data/src/10.7/sql/sql_parse.cc:8027

    #12 0x562c3c7be8c4 in dispatch_command(enum_server_command, THD*, char*, unsigned int, bool) /data/src/10.7/sql/sql_parse.cc:1894

    #13 0x562c3c7c42c5 in do_command(THD*, bool) /data/src/10.7/sql/sql_parse.cc:1407

    #14 0x562c3cb7b0cd in do_handle_one_connection(CONNECT*, bool) /data/src/10.7/sql/sql_connect.cc:1418

    #15 0x562c3cb7b60c in handle_one_connection /data/src/10.7/sql/sql_connect.cc:1312

    #16 0x562c3d64ad4b in pfs_spawn_thread /data/src/10.7/storage/perfschema/pfs.cc:2201

    #17 0x7fbc2b39dea6 in start_thread nptl/pthread_create.c:477

    #18 0x7fbc2af9cdee in __clone (/lib/x86_64-linux-gnu/libc.so.6+0xfddee)

0x629000097340 is located 4416 bytes inside of 16400-byte region [0x629000096200,0x62900009a210)

allocated by thread T5 here:

    #0 0x7fbc2b8a3e8f in __interceptor_malloc ../../../../src/libsanitizer/asan/asan_malloc_linux.cpp:145

    #1 0x562c3df3f238 in my_malloc /data/src/10.7/mysys/my_malloc.c:90

    #2 0x562c3df2bdeb in reset_root_defaults /data/src/10.7/mysys/my_alloc.c:243

    #3 0x562c3c66e673 in THD::init_for_queries() /data/src/10.7/sql/sql_class.cc:1387

    #4 0x562c3cb79092 in prepare_new_connection_state(THD*) /data/src/10.7/sql/sql_connect.cc:1240

    #5 0x562c3cb79947 in thd_prepare_connection(THD*) /data/src/10.7/sql/sql_connect.cc:1333

    #6 0x562c3cb79947 in thd_prepare_connection(THD*) /data/src/10.7/sql/sql_connect.cc:1322

    #7 0x562c3cb7b079 in do_handle_one_connection(CONNECT*, bool) /data/src/10.7/sql/sql_connect.cc:1408

    #8 0x562c3cb7b60c in handle_one_connection /data/src/10.7/sql/sql_connect.cc:1312

    #9 0x562c3d64ad4b in pfs_spawn_thread /data/src/10.7/storage/perfschema/pfs.cc:2201

    #10 0x7fbc2b39dea6 in start_thread nptl/pthread_create.c:477

Thread T5 created by T0 here:

    #0 0x7fbc2b84f2a2 in __interceptor_pthread_create ../../../../src/libsanitizer/asan/asan_interceptors.cpp:214

    #1 0x562c3d64afc9 in my_thread_create /data/src/10.7/storage/perfschema/my_thread.h:52

    #2 0x562c3d64afc9 in pfs_spawn_thread_v1 /data/src/10.7/storage/perfschema/pfs.cc:2252

    #3 0x562c3c48a47d in inline_mysql_thread_create /data/src/10.7/include/mysql/psi/mysql_thread.h:1139

    #4 0x562c3c48a47d in create_thread_to_handle_connection(CONNECT*) /data/src/10.7/sql/mysqld.cc:6008

    #5 0x562c3c496227 in handle_accepted_socket(st_mysql_socket, st_mysql_socket) /data/src/10.7/sql/mysqld.cc:6129

    #6 0x562c3c496d9f in handle_connections_sockets() /data/src/10.7/sql/mysqld.cc:6253

    #7 0x562c3c4986b0 in mysqld_main(int, char**) /data/src/10.7/sql/mysqld.cc:5903

    #8 0x7fbc2aec5d09 in __libc_start_main ../csu/libc-start.c:308

SUMMARY: AddressSanitizer: use-after-poison /data/src/10.7/sql/sql_select.cc:28482 in st_select_lex::print(THD*, String*, enum_query_type)

Shadow bytes around the buggy address:

  0x0c528000ae10: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00

  0x0c528000ae20: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00

  0x0c528000ae30: 00 00 00 00 00 f7 00 00 f7 00 00 00 00 f7 00 f7

  0x0c528000ae40: 00 00 f7 00 00 00 00 00 00 00 00 00 00 00 00 00

  0x0c528000ae50: 00 00 00 00 00 00 00 f7 00 00 00 00 00 00 00 00

=>0x0c528000ae60: 00 00 00 00 00 00 00 00[f7]00 00 00 00 00 00 00

  0x0c528000ae70: 00 00 00 00 00 00 00 00 00 f7 00 00 00 00 00 00

  0x0c528000ae80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00

  0x0c528000ae90: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00

  0x0c528000aea0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00

  0x0c528000aeb0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00

Shadow byte legend (one shadow byte represents 8 application bytes):

  Addressable:           00

  Partially addressable: 01 02 03 04 05 06 07 

  Heap left redzone:       fa

  Freed heap region:       fd

  Stack left redzone:      f1

  Stack mid redzone:       f2

  Stack right redzone:     f3

  Stack after return:      f5

  Stack use after scope:   f8

  Global redzone:          f9

  Global init order:       f6

  Poisoned by user:        f7

  Container overflow:      fc

  Array cookie:            ac

  Intra object redzone:    bb

  ASan internal:           fe

  Left alloca redzone:     ca

  Right alloca redzone:    cb

  Shadow gap:              cc

==1813883==ABORTING

commit 401ff6994d842a4072b7b155e5a958e178e6497a

Author: Eric Herman

Date:   Fri Sep 3 06:38:54 2021 +0200

    MDEV-26221: DYNAMIC_ARRAY use size_t for sizes