Memory not freed or Assertion `old_flags == ((my_flags & 0x10000U) ? 1 : 0)' failed in my_realloc upon ALTER on Aria table with GIS column

--source include/have_sequence.inc

CREATE TABLE t1 (pk INT PRIMARY KEY, a POINT DEFAULT ST_GEOMFROMTEXT('Point(1 1)')) ENGINE=Aria;

INSERT INTO t1 (pk) SELECT seq FROM seq_1_to_100;

SET SESSION ARIA_REPAIR_THREADS= 2;

ALTER TABLE t1 ROW_FORMAT=DYNAMIC;

# Cleanup

DROP TABLE t1;

mariadbd: /data/src/10.6/mysys/my_malloc.c:148: my_realloc: Assertion `old_flags == ((my_flags & 0x10000U) ? 1 : 0)' failed.

210615 11:30:08 [ERROR] mysqld got signal 6 ;

#7  0x00007f1f3cbf9f36 in __GI___assert_fail (assertion=0x561dd490de20 "old_flags == ((my_flags & 0x10000U) ? 1 : 0)", file=0x561dd490dce0 "/data/src/10.6/mysys/my_malloc.c", line=148, function=0x561dd490de78 <__PRETTY_FUNCTION__.15053> "my_realloc") at assert.c:101

#8  0x0000561dd4398f01 in my_realloc (key=0, old_point=0x7f1f1c082958, size=131, my_flags=64) at /data/src/10.6/mysys/my_malloc.c:148

#9  0x0000561dd3d5eaa3 in _ma_alloc_buffer (old_addr=0x7f1f1c082598, old_size=0x7f1f1c082860, new_size=131, flag=0) at /data/src/10.6/storage/maria/ma_open.c:1253

#10 0x0000561dd3dbb59d in sort_get_next_record (sort_param=0x7f1f1c0820c8) at /data/src/10.6/storage/maria/ma_check.c:5248

#11 0x0000561dd3dba161 in sort_key_read (sort_param=0x7f1f1c0820c8, key=0x7f1f200010e8 '\245' <repeats 200 times>...) at /data/src/10.6/storage/maria/ma_check.c:4811

#12 0x0000561dd3dc3b54 in _ma_thr_find_all_keys_exec (sort_param=0x7f1f1c0820c8) at /data/src/10.6/storage/maria/ma_sort.c:471

#13 0x0000561dd3dc3cdc in _ma_thr_find_all_keys (arg=0x7f1f1c0820c8) at /data/src/10.6/storage/maria/ma_sort.c:526

#14 0x0000561dd3e08ed9 in pfs_spawn_thread (arg=0x561dd799aab8) at /data/src/10.6/storage/perfschema/pfs.cc:2201

#15 0x00007f1f3d111609 in start_thread (arg=<optimized out>) at pthread_create.c:477

#16 0x00007f1f3cce5293 in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95

Warning: Memory not freed: 16

commit cc125bebfe9d06870cf1b66bd42c730398c8aa30

Author: Monty <monty@mariadb.org>

Date:   Wed Apr 14 13:40:36 2021 +0300

    Fix all warnings given by UBSAN