stack-use-after-scope in reinit_io_cache() detected by ASan

./mysql-test/mtr --debug-server innodb_bug12661768

==11845==ERROR: AddressSanitizer: stack-use-after-scope on address 0x7f6f48198250 at pc 0x5642cb4ab9c7 bp 0x7f6f48197950 sp 0x7f6f48197940
READ of size 8 at 0x7f6f48198250 thread T17
    #0 0x5642cb4ab9c6 in reinit_io_cache /mnt/hgfs/repos/percona-server/mysys/mf_iocache.c:342
    #1 0x5642cb39a502 in init_read_record(READ_RECORD*, THD*, TABLE*, SQL_SELECT*, int, bool, bool) /mnt/hgfs/repos/percona-server/sql/records.cc:232
    #2 0x5642caea11cd in mysql_update(THD*, TABLE_LIST*, List<Item>&, List<Item>&, Item*, unsigned int, st_order*, unsigned long long, enum_duplicates, bool, unsigned long long*, unsigned long long*) /mnt/hgfs/repos/percona-server/sql/sql_update.cc:621
    #3 0x5642cacd168c in mysql_execute_command(THD*) /mnt/hgfs/repos/percona-server/sql/sql_parse.cc:3098
    #4 0x5642cace2114 in mysql_parse(THD*, char*, unsigned int, Parser_state*) /mnt/hgfs/repos/percona-server/sql/sql_parse.cc:6116
    #5 0x5642cace7a2e in dispatch_command(enum_server_command, THD*, char*, unsigned int) /mnt/hgfs/repos/percona-server/sql/sql_parse.cc:1112
    #6 0x5642cacecfd4 in do_command(THD*) /mnt/hgfs/repos/percona-server/sql/sql_parse.cc:792
    #7 0x5642caf64d35 in do_handle_one_connection(THD*) /mnt/hgfs/repos/percona-server/sql/sql_connect.cc:1478
    #8 0x5642caf6503a in handle_one_connection /mnt/hgfs/repos/percona-server/sql/sql_connect.cc:1385
    #9 0x5642cb525c79 in pfs_spawn_thread /mnt/hgfs/repos/percona-server/storage/perfschema/pfs.cc:1015
    #10 0x7f6f580516da in start_thread (/lib/x86_64-linux-gnu/libpthread.so.0+0x76da)
    #11 0x7f6f56b3088e in __clone (/lib/x86_64-linux-gnu/libc.so.6+0x12188e)

Address 0x7f6f48198250 is located in stack of thread T17 at offset 1328 in frame
    #0 0x5642cae9f10b in mysql_update(THD*, TABLE_LIST*, List<Item>&, List<Item>&, Item*, unsigned int, st_order*, unsigned long long, enum_duplicates, bool, unsigned long long*, unsigned long long*) /mnt/hgfs/repos/percona-server/sql/sql_update.cc:260

  This frame has 20 object(s):
    [32, 33) 'need_sort'
    [96, 97) 'reverse'
    [160, 164) 'error'
    [224, 228) 'dup_key_found'
    [288, 292) 'table_count'
    [352, 356) 'cond_value'
    [416, 420) 'length'
    [480, 488) 'old_covering_keys'
    [544, 552) 'table'
    [608, 616) 'examined_rows'
    [672, 680) 'prelocking_strategy'
    [736, 744) 'tmp'
    [800, 808) 'table_list'
    [864, 872) 'conds'
    [928, 952) 'all_fields'
    [992, 1024) '_db_stack_frame_'
    [1056, 1088) '_db_stack_frame_'
    [1120, 1280) 'info'
    [1312, 1592) 'tempfile' <== Memory access at offset 1328 is inside this variable
    [1632, 2144) 'buff'
HINT: this may be a false positive if your program uses some custom stack unwind mechanism or swapcontext
      (longjmp and C++ exceptions *are* supported)
Thread T17 created by T0 here:
    #0 0x7f6f586d3043 in pthread_create (/usr/lib/x86_64-linux-gnu/libasan.so.5+0x4b043)
    #1 0x5642cb529535 in spawn_thread_v1 /mnt/hgfs/repos/percona-server/storage/perfschema/pfs.cc:1038
    #2 0x5642cab14c56 in inline_mysql_thread_create /mnt/hgfs/repos/percona-server/include/mysql/psi/mysql_thread.h:1049
    #3 0x5642cab14c56 in create_thread_to_handle_connection(THD*) /mnt/hgfs/repos/percona-server/sql/mysqld.cc:5334
    #4 0x5642cab16964 in create_new_thread /mnt/hgfs/repos/percona-server/sql/mysqld.cc:5432
    #5 0x5642cab16964 in handle_connections_sockets() /mnt/hgfs/repos/percona-server/sql/mysqld.cc:5692
    #6 0x5642cab1dc04 in mysqld_main(int, char**) /mnt/hgfs/repos/percona-server/sql/mysqld.cc:4946
    #7 0x5642cab02351 in main /mnt/hgfs/repos/percona-server/sql/main.cc:25
    #8 0x7f6f56a30b96 in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x21b96)

SUMMARY: AddressSanitizer: stack-use-after-scope /mnt/hgfs/repos/percona-server/mysys/mf_iocache.c:342 in reinit_io_cache
Shadow bytes around the buggy address:
  0x0fee6902aff0: 00 f2 f2 f2 f2 f2 f2 f2 f8 f2 f2 f2 f2 f2 f2 f2
  0x0fee6902b000: 00 f2 f2 f2 f2 f2 f2 f2 00 f2 f2 f2 f2 f2 f2 f2
  0x0fee6902b010: 00 f2 f2 f2 f2 f2 f2 f2 00 00 00 f2 f2 f2 f2 f2
  0x0fee6902b020: 00 00 00 00 f2 f2 f2 f2 00 00 00 00 f2 f2 f2 f2
  0x0fee6902b030: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
=>0x0fee6902b040: 00 00 00 00 f2 f2 f2 f2 f8 f8[f8]f8 f8 f8 f8 f8
  0x0fee6902b050: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
  0x0fee6902b060: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f2 f2 f2 f2 f2
  0x0fee6902b070: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x0fee6902b080: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x0fee6902b090: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
Shadow byte legend (one shadow byte represents 8 application bytes):
  Addressable:           00
  Partially addressable: 01 02 03 04 05 06 07
  Heap left redzone:       fa
  Freed heap region:       fd
  Stack left redzone:      f1
  Stack mid redzone:       f2
  Stack right redzone:     f3
  Stack after return:      f5
  Stack use after scope:   f8
  Global redzone:          f9
  Global init order:       f6
  Poisoned by user:        f7
  Container overflow:      fc
  Array cookie:            ac
  Intra object redzone:    bb
  ASan internal:           fe
  Left alloca redzone:     ca
  Right alloca redzone:    cb
==11845==ABORTING