MSAN use-of-uninitialized-value in build_frm_image()

CURRENT_TEST: innodb.innodb-online-alter-gis

mysqltest: At line 29: query 'ALTER TABLE t1 ADD COLUMN b LINESTRING DEFAULT POINT(1,1)' failed with wrong errno 2013: 'Lost connection to MySQL server during query', instead of 1366...

…

----------SERVER LOG START-----------

==1438499==WARNING: MemorySanitizer: use-of-uninitialized-value

    #0 0x55b800771577 in Binary_string::c_ptr() /mariadb/10.5m/sql/sql_string.h:606:9

    #1 0x55b800771577 in Field_geom::store(char const*, unsigned long, charset_info_st const*) /mariadb/10.5m/sql/sql_type_geom.cc:875:13

    #2 0x55b800bf16e7 in Item::save_str_in_field(Field*, bool) /mariadb/10.5m/sql/item.cc:6527:21

    #3 0x55b800bf28ab in Item::save_in_field(Field*, bool) /mariadb/10.5m/sql/item.cc:6565:30

    #4 0x55b800a95bae in Field_blob::make_empty_rec_store_default_value(THD*, Item*) /mariadb/10.5m/sql/field.cc:8782:18

    #5 0x55b8003ead07 in make_empty_rec_store_default(THD*, Field*, Virtual_column_info*) /mariadb/10.5m/sql/unireg.cc:1096:19

    #6 0x55b8003ead07 in make_empty_rec(THD*, unsigned char*, unsigned int, List<Create_field>&, unsigned int, unsigned long) /mariadb/10.5m/sql/unireg.cc:1171:12

    #7 0x55b8003ead07 in build_frm_image(THD*, st_mysql_const_lex_string const&, HA_CREATE_INFO*, List<Create_field>&, unsigned int, st_key*, handler*) /mariadb/10.5m/sql/unireg.cc:534:7

    #8 0x55b8002385e2 in mysql_create_frm_image(THD*, st_mysql_const_lex_string const&, st_mysql_const_lex_string const&, HA_CREATE_INFO*, Alter_info*, int, st_key**, unsigned int*, st_mysql_const_unsigned_lex_string*) /mariadb/10.5m/sql/sql_table.cc:4870:9

    #9 0x55b80023d7da in create_table_impl(THD*, st_mysql_const_lex_string const&, st_mysql_const_lex_string const&, st_mysql_const_lex_string const&, st_mysql_const_lex_string const&, char const*, DDL_options_st, HA_CREATE_INFO*, Alter_info*, int, bool*, st_key**, unsigned int*, st_mysql_const_unsigned_lex_string*) /mariadb/10.5m/sql/sql_table.cc:5120:11

    #10 0x55b80026b736 in mysql_alter_table(THD*, st_mysql_const_lex_string const*, st_mysql_const_lex_string const*, HA_CREATE_INFO*, TABLE_LIST*, Alter_info*, unsigned int, st_order*, bool, bool) /mariadb/10.5m/sql/sql_table.cc:10214:10

    #11 0x55b8004cfb11 in Sql_cmd_alter_table::execute(THD*) /mariadb/10.5m/sql/sql_alter.cc:522:11

    #12 0x55b7ffeac1d1 in mysql_execute_command(THD*) /mariadb/10.5m/sql/sql_parse.cc:5908:26

    #13 0x55b7ffe9417e in mysql_parse(THD*, char*, unsigned int, Parser_state*, bool, bool) /mariadb/10.5m/sql/sql_parse.cc:7953:18

    #14 0x55b7ffe86543 in dispatch_command(enum_server_command, THD*, char*, unsigned int, bool, bool) /mariadb/10.5m/sql/sql_parse.cc:1839:7

    #15 0x55b7ffe96c74 in do_command(THD*) /mariadb/10.5m/sql/sql_parse.cc:1358:17

    #16 0x55b8004af6fb in do_handle_one_connection(CONNECT*, bool) /mariadb/10.5m/sql/sql_connect.cc:1422:11

    #17 0x55b8004aed66 in handle_one_connection /mariadb/10.5m/sql/sql_connect.cc:1319:5

    #18 0x55b801949287 in pfs_spawn_thread /mariadb/10.5m/storage/perfschema/pfs.cc:2201:3

    #19 0x7f28135d5f26 in start_thread /build/glibc-WZtAaN/glibc-2.30/nptl/pthread_create.c:479:8

    #20 0x7f28130b42ee in clone /build/glibc-WZtAaN/glibc-2.30/misc/../sysdeps/unix/sysv/linux/x86_64/clone.S:95

  Memory was marked as uninitialized

    #0 0x55b7ff9413ae in __msan_allocated_memory (/dev/shm/10.5m/sql/mariadbd+0x6fe3ae)

    #1 0x55b802fe5f75 in my_malloc /mariadb/10.5m/mysys/my_malloc.c:111:7