ASAN global-buffer-overflow in ma_net_write_buff / libmariadb

perl ./mtr unit.conc_errors

==7774==ERROR: AddressSanitizer: global-buffer-overflow on address 0x555f8b359d00 at pc 0x555f8b34f66e bp 0x7ffe05183c10 sp 0x7ffe05183c08

READ of size 100 at 0x555f8b359d00 thread T0

    #0 0x555f8b34f66d in ma_net_write_buff /data/src/10.2-bug/libmariadb/libmariadb/ma_net.c:287

    #1 0x555f8b34f09e in ma_net_write_command /data/src/10.2-bug/libmariadb/libmariadb/ma_net.c:241

    #2 0x555f8b2cf5e9 in mthd_my_send_cmd /data/src/10.2-bug/libmariadb/libmariadb/mariadb_lib.c:396

    #3 0x555f8b300023 in mysql_stmt_prepare /data/src/10.2-bug/libmariadb/libmariadb/mariadb_stmt.c:1616

    #4 0x555f8b2cc78d in test_parse_error_and_bad_length /data/src/10.2-bug/libmariadb/unittest/libmariadb/errors.c:257

    #5 0x555f8b2cb03f in run_tests /data/src/10.2-bug/libmariadb/unittest/libmariadb/my_test.h:579

    #6 0x555f8b2cc813 in main /data/src/10.2-bug/libmariadb/unittest/libmariadb/errors.c:284

    #7 0x7fd7120d32b0 in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x202b0)

    #8 0x555f8b2c93c9 in _start (/data/src/10.2-bug/libmariadb/unittest/libmariadb/errors+0x243c9)

0x555f8b359d0f is located 0 bytes to the right of global variable '*.LC87' from '/data/src/10.2-bug/libmariadb/unittest/libmariadb/errors.c' (0x555f8b359d00) of size 15

  '*.LC87' is ascii string 'SHOW DATABASES'

SUMMARY: AddressSanitizer: global-buffer-overflow /data/src/10.2-bug/libmariadb/libmariadb/ma_net.c:287 ma_net_write_buff

Shadow bytes around the buggy address:

  0x0aac71663350: 00 00 00 00 00 02 f9 f9 f9 f9 f9 f9 00 06 f9 f9

  0x0aac71663360: f9 f9 f9 f9 00 00 00 00 f9 f9 f9 f9 00 06 f9 f9

  0x0aac71663370: f9 f9 f9 f9 00 06 f9 f9 f9 f9 f9 f9 00 00 00 00

  0x0aac71663380: 00 f9 f9 f9 f9 f9 f9 f9 00 00 02 f9 f9 f9 f9 f9

  0x0aac71663390: 00 07 f9 f9 f9 f9 f9 f9 00 00 03 f9 f9 f9 f9 f9

=>0x0aac716633a0:[00]07 f9 f9 f9 f9 f9 f9 00 00 05 f9 f9 f9 f9 f9

  0x0aac716633b0: 00 00 00 f9 f9 f9 f9 f9 00 00 05 f9 f9 f9 f9 f9

  0x0aac716633c0: 00 00 03 f9 f9 f9 f9 f9 00 00 06 f9 f9 f9 f9 f9

  0x0aac716633d0: 00 00 03 f9 f9 f9 f9 f9 00 00 01 f9 f9 f9 f9 f9

  0x0aac716633e0: 00 06 f9 f9 f9 f9 f9 f9 00 00 f9 f9 f9 f9 f9 f9

  0x0aac716633f0: 00 00 00 00 f9 f9 f9 f9 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

  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

==7774==ABORTING