MSAN: use-of-uninitialized-value in process_dbl_arg on SELECT when optimizer_trace is active

SET SESSION optimizer_trace=1;

CREATE TABLE t (c INT) ENGINE=InnoDB;

SELECT * FROM t;

==440042==WARNING: MemorySanitizer: use-of-uninitialized-value

    #0 0x5ac2161d6980 in process_dbl_arg /test/11.8_dbg_san/strings/my_vsnprintf.c:314:10

    #1 0x5ac2161d6980 in my_vsnprintf_ex /test/11.8_dbg_san/strings/my_vsnprintf.c:727:11

    #2 0x5ac2161d771b in my_vsnprintf /test/11.8_dbg_san/strings/my_vsnprintf.c:798:10

    #3 0x5ac2161d771b in my_snprintf /test/11.8_dbg_san/strings/my_vsnprintf.c:807:11

    #4 0x5ac21511ea88 in Json_writer::add_double(double) /test/11.8_dbg_san/sql/my_json_writer.cc:234:15

    #5 0x5ac2152799ea in Json_value_helper::add_double(double) /test/11.8_dbg_san/sql/my_json_writer.h:348:15

    #6 0x5ac2152799ea in Json_writer_object::add(char const*, double) /test/11.8_dbg_san/sql/my_json_writer.h:509:15

    #7 0x5ac2152799ea in add_table_scan_values_to_trace(THD*, st_join_table*) /test/11.8_dbg_san/sql/opt_trace.cc:635:5

    #8 0x5ac214b54299 in make_join_statistics(JOIN*, List<TABLE_LIST>&, st_dynamic_array*) /test/11.8_dbg_san/sql/sql_select.cc:6315:11

    #9 0x5ac214b42f73 in JOIN::optimize_inner() /test/11.8_dbg_san/sql/sql_select.cc:2728:7

    #10 0x5ac214b365a2 in JOIN::optimize() /test/11.8_dbg_san/sql/sql_select.cc:2010:10

    #11 0x5ac214b1de46 in mysql_select(THD*, TABLE_LIST*, List<Item>&, Item*, unsigned int, st_order*, st_order*, Item*, st_order*, unsigned long long, select_result*, st_select_lex_unit*, st_select_lex*) /test/11.8_dbg_san/sql/sql_select.cc:5373:19

    #12 0x5ac214b1d58a in handle_select(THD*, LEX*, select_result*, unsigned long long) /test/11.8_dbg_san/sql/sql_select.cc:633:10

    #13 0x5ac214a5a860 in execute_sqlcom_select(THD*, TABLE_LIST*) /test/11.8_dbg_san/sql/sql_parse.cc:6190:12

    #14 0x5ac214a480d3 in mysql_execute_command(THD*, bool) /test/11.8_dbg_san/sql/sql_parse.cc:3975:12

    #15 0x5ac214a368af in mysql_parse(THD*, char*, unsigned int, Parser_state*) /test/11.8_dbg_san/sql/sql_parse.cc:7905:18

    #16 0x5ac214a2f74f in dispatch_command(enum_server_command, THD*, char*, unsigned int, bool) /test/11.8_dbg_san/sql/sql_parse.cc:1903:7

    #17 0x5ac214a37733 in do_command(THD*, bool) /test/11.8_dbg_san/sql/sql_parse.cc:1416:17

    #18 0x5ac214f47a6c in do_handle_one_connection(CONNECT*, bool) /test/11.8_dbg_san/sql/sql_connect.cc:1415:11

    #19 0x5ac214f473e6 in handle_one_connection /test/11.8_dbg_san/sql/sql_connect.cc:1327:5

    #20 0x7e8f7789ca93 in start_thread nptl/pthread_create.c:447:8

    #21 0x7e8f77929c3b in clone3 misc/../sysdeps/unix/sysv/linux/x86_64/clone3.S:78

  Uninitialized value was stored to memory at

    #0 0x5ac2161d6979 in my_vsnprintf_ex /test/11.8_dbg_san/strings/my_vsnprintf.c:726:10

    #1 0x5ac2161d771b in my_vsnprintf /test/11.8_dbg_san/strings/my_vsnprintf.c:798:10

    #2 0x5ac2161d771b in my_snprintf /test/11.8_dbg_san/strings/my_vsnprintf.c:807:11

    #3 0x5ac21511ea88 in Json_writer::add_double(double) /test/11.8_dbg_san/sql/my_json_writer.cc:234:15

    #4 0x5ac2152799ea in Json_value_helper::add_double(double) /test/11.8_dbg_san/sql/my_json_writer.h:348:15

    #5 0x5ac2152799ea in Json_writer_object::add(char const*, double) /test/11.8_dbg_san/sql/my_json_writer.h:509:15

    #6 0x5ac2152799ea in add_table_scan_values_to_trace(THD*, st_join_table*) /test/11.8_dbg_san/sql/opt_trace.cc:635:5

    #7 0x5ac214b54299 in make_join_statistics(JOIN*, List<TABLE_LIST>&, st_dynamic_array*) /test/11.8_dbg_san/sql/sql_select.cc:6315:11

    #8 0x5ac214b42f73 in JOIN::optimize_inner() /test/11.8_dbg_san/sql/sql_select.cc:2728:7

    #9 0x5ac214b365a2 in JOIN::optimize() /test/11.8_dbg_san/sql/sql_select.cc:2010:10

    #10 0x5ac214b1de46 in mysql_select(THD*, TABLE_LIST*, List<Item>&, Item*, unsigned int, st_order*, st_order*, Item*, st_order*, unsigned long long, select_result*, st_select_lex_unit*, st_select_lex*) /test/11.8_dbg_san/sql/sql_select.cc:5373:19

    #11 0x5ac214b1d58a in handle_select(THD*, LEX*, select_result*, unsigned long long) /test/11.8_dbg_san/sql/sql_select.cc:633:10

    #12 0x5ac214a5a860 in execute_sqlcom_select(THD*, TABLE_LIST*) /test/11.8_dbg_san/sql/sql_parse.cc:6190:12

    #13 0x5ac214a480d3 in mysql_execute_command(THD*, bool) /test/11.8_dbg_san/sql/sql_parse.cc:3975:12

    #14 0x5ac214a368af in mysql_parse(THD*, char*, unsigned int, Parser_state*) /test/11.8_dbg_san/sql/sql_parse.cc:7905:18

    #15 0x5ac214a2f74f in dispatch_command(enum_server_command, THD*, char*, unsigned int, bool) /test/11.8_dbg_san/sql/sql_parse.cc:1903:7

    #16 0x5ac214a37733 in do_command(THD*, bool) /test/11.8_dbg_san/sql/sql_parse.cc:1416:17

    #17 0x5ac214f47a6c in do_handle_one_connection(CONNECT*, bool) /test/11.8_dbg_san/sql/sql_connect.cc:1415:11

    #18 0x5ac214f473e6 in handle_one_connection /test/11.8_dbg_san/sql/sql_connect.cc:1327:5

    #19 0x7e8f7789ca93 in start_thread nptl/pthread_create.c:447:8

  Uninitialized value was created by an allocation of 'path' in the stack frame

    #0 0x5ac2156d8905 in ha_innobase::info_low(unsigned int, bool) /test/11.8_dbg_san/storage/innobase/handler/ha_innodb.cc:14800:2

SUMMARY: MemorySanitizer: use-of-uninitialized-value /test/11.8_dbg_san/strings/my_vsnprintf.c:314:10 in process_dbl_arg