Server crash in key_copy / get_matching_chain_by_join_key or valgrind warnings

CREATE TABLE t1 (a VARCHAR(10)) ENGINE=MyISAM;

CREATE OR REPLACE ALGORITHM=TEMPTABLE VIEW v1 AS SELECT * FROM t1;

INSERT INTO t1 VALUES ('foo'),('bar');

CREATE TABLE t2 (b integer auto_increment primary key) ENGINE=MyISAM;

INSERT INTO t2 VALUES (NULL),(NULL);

CREATE TABLE t3 (c VARCHAR(1024) CHARACTER SET utf8, d INT) ENGINE=MyISAM;

CREATE OR REPLACE ALGORITHM=TEMPTABLE VIEW v3 AS SELECT * FROM t3;

INSERT INTO t3 VALUES ('abc',NULL),('def',4);

SET join_cache_level= 8;

SELECT * FROM v1, t2, v3 WHERE a = c AND b = d;

# Cleanup

DROP VIEW v1, v3;

DROP TABLE t1, t2, t3;

#2  <signal handler called>

#3  key_copy (to_key=0x7f1931dcda25 "", from_record=0x7f1931cfa018 "\375\003", key_info=<optimized out>, key_length=3070, with_zerofill=with_zerofill@entry=true) at /home/buildbot/buildbot/build/sql/key.cc:155

#4  0x0000000000679c8c in get_matching_chain_by_join_key (this=0x7f1931dcd870) at /home/buildbot/buildbot/build/sql/sql_join_cache.cc:3640

#5  JOIN_CACHE_BNLH::prepare_look_for_matches (this=0x7f1931dcd870, skip_last=<optimized out>) at /home/buildbot/buildbot/build/sql/sql_join_cache.cc:3677

#6  0x0000000000678e69 in JOIN_CACHE::join_matching_records (this=0x7f1931dcd870, skip_last=false) at /home/buildbot/buildbot/build/sql/sql_join_cache.cc:2277

#7  0x0000000000678948 in JOIN_CACHE::join_records (this=this@entry=0x7f1931dcd870, skip_last=skip_last@entry=false) at /home/buildbot/buildbot/build/sql/sql_join_cache.cc:2091

#8  0x00000000005c381a in sub_select_cache (join=0x7f1931cf2018, join_tab=0x7f1931d63918, end_of_records=<optimized out>) at /home/buildbot/buildbot/build/sql/sql_select.cc:16768

#9  0x00000000005da513 in sub_select (join_tab=0x7f1931d635f8, join=0x7f1931cf2018, end_of_records=<optimized out>) at /home/buildbot/buildbot/build/sql/sql_select.cc:16938

#10 do_select (join=join@entry=0x7f1931cf2018, fields=fields@entry=0x7f1932603980, table=table@entry=0x0, procedure=0x0) at /home/buildbot/buildbot/build/sql/sql_select.cc:16649

#11 0x00000000005efd94 in JOIN::exec (this=this@entry=0x7f1931cf2018) at /home/buildbot/buildbot/build/sql/sql_select.cc:2878

#12 0x00000000005eb0a5 in mysql_select (thd=thd@entry=0x7f1932600000, rref_pointer_array=rref_pointer_array@entry=0x7f1932603ad8, tables=0x7f1931d02238, wild_num=<optimized out>, fields=..., conds=<optimized out>, og_num=0, order=0x0, group=0x0, having=0x0, proc_param=0x0, select_options=2147748608, result=result@entry=0x7f1931cf7f00, unit=0x7f1932603188, select_lex=select_lex@entry=0x7f1932603868) at /home/buildbot/buildbot/build/sql/sql_select.cc:3099

#13 0x00000000005f1cc3 in handle_select (thd=thd@entry=0x7f1932600000, lex=lex@entry=0x7f19326030d8, result=result@entry=0x7f1931cf7f00, setup_tables_done_option=setup_tables_done_option@entry=0) at /home/buildbot/buildbot/build/sql/sql_select.cc:319

#14 0x000000000059bd18 in execute_sqlcom_select (thd=thd@entry=0x7f1932600000, all_tables=0x7f1931d02238) at /home/buildbot/buildbot/build/sql/sql_parse.cc:4686

#15 0x00000000005a3ba3 in mysql_execute_command (thd=thd@entry=0x7f1932600000) at /home/buildbot/buildbot/build/sql/sql_parse.cc:2234

#16 0x00000000005a74c4 in mysql_parse (thd=thd@entry=0x7f1932600000, parser_state=parser_state@entry=0x7f19384bc6e0, length=<optimized out>, rawbuf=<optimized out>) at /home/buildbot/buildbot/build/sql/sql_parse.cc:5931

#17 0x00000000005a9983 in dispatch_command (command=COM_QUERY, thd=0x7f1932600000, packet=<optimized out>, packet_length=46) at /home/buildbot/buildbot/build/sql/sql_parse.cc:1245

#18 0x00000000005a9afe in do_command (thd=<optimized out>) at /home/buildbot/buildbot/build/sql/sql_parse.cc:793

#19 0x000000000065c58b in do_handle_one_connection (thd_arg=thd_arg@entry=0x7f1932600000) at /home/buildbot/buildbot/build/sql/sql_connect.cc:1268

#20 0x000000000065c60c in handle_one_connection (arg=arg@entry=0x7f1932600000) at /home/buildbot/buildbot/build/sql/sql_connect.cc:1184

#21 0x0000000000979828 in pfs_spawn_thread (arg=0x7f1936441d30) at /home/buildbot/buildbot/build/storage/perfschema/pfs.cc:1015

#22 0x00007f1937aaa494 in start_thread (arg=0x7f19384bd700) at pthread_create.c:333

#23 0x00007f193716793f in clone () from /lib/x86_64-linux-gnu/libc.so.6

==29579== Thread 4:

==29579== Invalid read of size 1

==29579==    at 0x87E2CA: key_copy(unsigned char*, unsigned char*, st_key*, unsigned int, bool) (key.cc:124)

==29579==    by 0x73B9A2: JOIN_CACHE_BNLH::get_matching_chain_by_join_key() (sql_join_cache.cc:3640)

==29579==    by 0x73BA33: JOIN_CACHE_BNLH::prepare_look_for_matches(bool) (sql_join_cache.cc:3677)

==29579==    by 0x739A68: JOIN_CACHE::join_matching_records(bool) (sql_join_cache.cc:2277)

==29579==    by 0x739532: JOIN_CACHE::join_records(bool) (sql_join_cache.cc:2091)

==29579==    by 0x660045: sub_select_cache(JOIN*, st_join_table*, bool) (sql_select.cc:16843)

==29579==    by 0x660250: sub_select(JOIN*, st_join_table*, bool) (sql_select.cc:17013)

==29579==    by 0x65FD39: do_select(JOIN*, List<Item>*, TABLE*, Procedure*) (sql_select.cc:16724)

==29579==    by 0x63DF57: JOIN::exec() (sql_select.cc:2882)

==29579==    by 0x63E735: 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*) (sql_select.cc:3103)

==29579==    by 0x634DD9: handle_select(THD*, LEX*, select_result*, unsigned long) (sql_select.cc:319)

==29579==    by 0x60D4D0: execute_sqlcom_select(THD*, TABLE_LIST*) (sql_parse.cc:4685)

==29579==    by 0x606843: mysql_execute_command(THD*) (sql_parse.cc:2233)

==29579==    by 0x6100B9: mysql_parse(THD*, char*, unsigned int, Parser_state*) (sql_parse.cc:5930)

==29579==    by 0x603D9E: dispatch_command(enum_server_command, THD*, char*, unsigned int) (sql_parse.cc:1075)

==29579==    by 0x602FAA: do_command(THD*) (sql_parse.cc:793)

==29579==  Address 0xa957353 is 19 bytes after a block of size 64 in arena "client"