Uninitialized tbl_len in dict_acquire_mdl_shared() in purge after DDL

#10 0x0000558a21f88cef in memcpy (__len=<optimized out>, __src=0x14af1c3f0740, __dest=0x14af1c3f0670)

    at /usr/include/x86_64-linux-gnu/bits/string_fortified.h:34

#11 dict_acquire_mdl_shared<false> (table=table@entry=0x14aee838fef0, thd=thd@entry=0x558a24399468, 

    mdl=mdl@entry=0x558a24285b00, table_op=table_op@entry=DICT_TABLE_OP_NORMAL)

    at /test/10.5_opt/storage/innobase/dict/dict0dict.cc:904

#12 0x0000558a21f84110 in dict_table_open_on_id (table_id=98, dict_locked=dict_locked@entry=false, 

    table_op=table_op@entry=DICT_TABLE_OP_NORMAL, thd=0x558a24399468, mdl=mdl@entry=0x558a24285b00)

    at /test/10.5_opt/storage/innobase/dict/dict0dict.cc:946

#13 0x0000558a21e867e6 in row_purge_parse_undo_rec (thr=0x558a24285780, 

    updated_extern=0x14af1c3f0abe, undo_rec=0x558a24357470 "", node=0x558a24285960)

    at /test/10.5_opt/storage/innobase/row/row0purge.cc:933

  size_t db1_len, tbl1_len;

  table->parse_name<!trylock>(db_buf1, tbl_buf1, &db1_len, &tbl1_len);

  if (*mdl)

  {

    if (db_len == db1_len && tbl_len == tbl1_len &&

        !memcmp(db_buf, db_buf1, db_len) &&

        !memcmp(tbl_buf, tbl_buf1, tbl_len))

      return table;

    /* The table was renamed. Release MDL for the old name and

    try to acquire MDL for the new name. */

    mdl_context->release_lock(*mdl);

    *mdl= nullptr;

  }

  db_len= db1_len;

  tbl_len= tbl1_len;

  memcpy(tbl_buf, tbl_buf1, tbl_len + 1);

  memcpy(db_buf, db_buf1, db_len + 1);

  goto retry;

}

diff --git a/storage/innobase/dict/dict0dict.cc b/storage/innobase/dict/dict0dict.cc

index e7cb05307d0..76537b2f41d 100644

--- a/storage/innobase/dict/dict0dict.cc

+++ b/storage/innobase/dict/dict0dict.cc

@@ -758,7 +758,10 @@ bool dict_table_t::parse_name(char (&db_name)[NAME_LEN + 1],

   if (tbl_len > TEMP_FILE_PREFIX_LENGTH

       && !strncmp(tbl_buf, TEMP_FILE_PREFIX, TEMP_FILE_PREFIX_LENGTH))

+  {

+    *tbl_name_len= tbl_len;

     return false;

+  }

   if (char* is_part= strchr(tbl_buf, '#'))

     *is_part= '\0';