ASAN heap-use-after-free in my_strnncoll_binary upon a mix of char functions

SELECT BIT_AND(NULL) AS f FROM DUAL ORDER BY GREATEST( CAST( CONVERT( 'foo' USING latin1 ) AS BINARY(1) ), CHARSET('foo') );

==23747==ERROR: AddressSanitizer: heap-use-after-free on address 0x60c000028eb0 at pc 0x564fd6a93d76 bp 0x7f38d33468e0 sp 0x7f38d33468d8

READ of size 1 at 0x60c000028eb0 thread T6

    #0 0x564fd6a93d75 in my_strnncoll_binary /data/src/10.1/strings/ctype-bin.c:85

    #1 0x564fd6a93e0b in my_strnncollsp_binary /data/src/10.1/strings/ctype-bin.c:126

    #2 0x564fd589ed80 in sortcmp(String const*, String const*, charset_info_st const*) /data/src/10.1/sql/sql_string.cc:771

    #3 0x564fd5d494d9 in Item_func_min_max::val_str(String*) /data/src/10.1/sql/item_func.cc:2977

    #4 0x564fd5c59c97 in Item_copy_string::copy() /data/src/10.1/sql/item.cc:4063

    #5 0x564fd57e4cfb in copy_fields(TMP_TABLE_PARAM*) /data/src/10.1/sql/sql_select.cc:23163

    #6 0x564fd57f2e35 in end_send_group(JOIN*, st_join_table*, bool) /data/src/10.1/sql/sql_select.cc:19816

    #7 0x564fd57dd27d in do_select /data/src/10.1/sql/sql_select.cc:18091

    #8 0x564fd582226e in JOIN::exec_inner() /data/src/10.1/sql/sql_select.cc:3275

    #9 0x564fd5823556 in JOIN::exec() /data/src/10.1/sql/sql_select.cc:2562

    #10 0x564fd5817da9 in mysql_select(THD*, Item***, TABLE_LIST*, unsigned int, List<Item>&, Item*, unsigned int, st_order*, st_order*, Item*, st_order*, unsigned long long, select_result*, st_select_lex_unit*, st_select_lex*) /data/src/10.1/sql/sql_select.cc:3499

    #11 0x564fd5818597 in handle_select(THD*, LEX*, select_result*, unsigned long) /data/src/10.1/sql/sql_select.cc:388

    #12 0x564fd56e7603 in execute_sqlcom_select /data/src/10.1/sql/sql_parse.cc:5991

    #13 0x564fd570194d in mysql_execute_command(THD*) /data/src/10.1/sql/sql_parse.cc:3042

    #14 0x564fd5719af0 in mysql_parse(THD*, char*, unsigned int, Parser_state*) /data/src/10.1/sql/sql_parse.cc:7509

    #15 0x564fd57208a2 in dispatch_command(enum_server_command, THD*, char*, unsigned int) /data/src/10.1/sql/sql_parse.cc:1496

    #16 0x564fd5727074 in do_command(THD*) /data/src/10.1/sql/sql_parse.cc:1124

    #17 0x564fd59cf5e7 in do_handle_one_connection(THD*) /data/src/10.1/sql/sql_connect.cc:1330

    #18 0x564fd59cfaf8 in handle_one_connection /data/src/10.1/sql/sql_connect.cc:1242

    #19 0x564fd629f24e in pfs_spawn_thread /data/src/10.1/storage/perfschema/pfs.cc:1861

    #20 0x7f38dfab1493 in start_thread (/lib/x86_64-linux-gnu/libpthread.so.0+0x7493)

    #21 0x7f38dde6a93e in __clone (/lib/x86_64-linux-gnu/libc.so.6+0xe893e)

0x60c000028eb0 is located 112 bytes inside of 124-byte region [0x60c000028e40,0x60c000028ebc)

freed by thread T6 here:

    #0 0x7f38dfd1b527 in __interceptor_free (/usr/lib/x86_64-linux-gnu/libasan.so.1+0x54527)

    #1 0x564fd6a6b7cf in free_memory /data/src/10.1/mysys/safemalloc.c:276

previously allocated by thread T6 here:

    #0 0x7f38dfd1b73f in malloc (/usr/lib/x86_64-linux-gnu/libasan.so.1+0x5473f)

    #1 0x564fd6a6b8a0 in sf_malloc /data/src/10.1/mysys/safemalloc.c:115

    #2 0x564fd6b642da (/data/bld/10.1-asan/bin/mysqld+0x1da02da)

Thread T6 created by T0 here:

    #0 0x7f38dfceabba in pthread_create (/usr/lib/x86_64-linux-gnu/libasan.so.1+0x23bba)

    #1 0x564fd62aaaa5 in spawn_thread_v1 /data/src/10.1/storage/perfschema/pfs.cc:1911

SUMMARY: AddressSanitizer: heap-use-after-free /data/src/10.1/strings/ctype-bin.c:85 my_strnncoll_binary

Shadow bytes around the buggy address:

  0x0c187fffd180: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa

  0x0c187fffd190: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa

  0x0c187fffd1a0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa

  0x0c187fffd1b0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa

  0x0c187fffd1c0: fa fa fa fa fa fa fa fa fd fd fd fd fd fd fd fd

=>0x0c187fffd1d0: fd fd fd fd fd fd[fd]fd fa fa fa fa fa fa fa fa

  0x0c187fffd1e0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 04

  0x0c187fffd1f0: fa fa fa fa fa fa fa fa 00 00 00 00 00 00 00 00

  0x0c187fffd200: 00 00 00 00 00 00 00 04 fa fa fa fa fa fa fa fa

  0x0c187fffd210: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd

  0x0c187fffd220: fa fa fa fa fa fa fa fa fd fd fd fd fd fd fd fd

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

  Heap right redzone:      fb

  Freed heap region:       fd

  Stack left redzone:      f1

  Stack mid redzone:       f2

  Stack right redzone:     f3

  Stack partial redzone:   f4

  Stack after return:      f5

  Stack use after scope:   f8

  Global redzone:          f9

  Global init order:       f6

  Poisoned by user:        f7

  Contiguous container OOB:fc

  ASan internal:           fe

==23747==ABORTING

f

18446744073709551615

Warnings:

Warning	1292	Truncated incorrect BINARY(1) value: 'foo'