Hi,

I obtained a segfault when trying to alter a table in mariadb 10.13.
It's not reproduced 100% of the time but roughly 50% of the time, and looks similar to https://jira.mariadb.org/browse/MDEV-17177 .

1. mysqld --version
   /usr/sbin/mysqld Ver 10.4.13-MariaDB-1:10.4.13+maria~bionic for debian-linux-gnu on x86_64 (mariadb.org binary distribution)

When launching from gdb I obtained the following backtrace :
{{
Thread 43 "mysqld" received signal SIGSEGV, Segmentation fault.
[Switching to Thread 0x7ffff03e2700 (LWP 27295)]
0x0000555555eea267 in Item_func_in::cleanup() ()
(gdb) bt
#0 0x0000555555eea267 in Item_func_in::cleanup() ()
#1 0x0000555555b69c2d in Query_arena::free_items() ()
#2 0x0000555555b6bb4b in THD::cleanup_after_query() ()
#3 0x0000555555bbc02b in mysql_parse(THD*, char*, unsigned int, Parser_state*, bool, bool) ()
#4 0x0000555555bbe705 in dispatch_command(enum_server_command, THD*, char*, unsigned int, bool, bool) ()
#5 0x0000555555bbfbb4 in do_command(THD*) ()
#6 0x0000555555c9c23e in do_handle_one_connection(CONNECT*) ()
#7 0x0000555555c9c2fd in handle_one_connection ()
#8 0x00007ffff70d86db in start_thread (arg=0x7ffff03e2700) at pthread_create.c:463
#9 0x00007ffff5afaa3f in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95
}}

The errors happens when altering a table to add or remove a column, here my command was
ALTER TABLE nodegroup DROP COLUMN stack_id;