MDEV-12725 select on federated table crashes server

NET can only store current_thd if this NET (or its MYSQL) is not
moved between threads. In FederatedX MYSQL is part of the TABLE,
and a TABLE can migrate between threads.

Fix: associate NET with THD in txn->acquire() , and dissociate
in txn->release()

mysql-test/suite/federated/net_thd_crash-12725.result

+SET GLOBAL query_cache_size= 16*1024*1024;
+SET GLOBAL query_cache_type= 1;
+CREATE TABLE t1 (i INT);
+CREATE TABLE t2 (i INT) ENGINE=FEDERATED CONNECTION="mysql://root@localhost:MASTER_MYPORT/test/t1";
+ALTER TABLE t2 DISABLE KEYS;
+ERROR HY000: Storage engine FEDERATED of the table `test`.`t2` doesn't have this option
+CREATE TABLE t3 (i INT) ENGINE=FEDERATED CONNECTION="mysql://root@localhost:MASTER_MYPORT/test/t1";
+SET GLOBAL query_cache_size= default;
+SET GLOBAL query_cache_type= default;
+drop table t1, t2, t3;

mysql-test/suite/federated/net_thd_crash-12725.test

+#
+# MDEV-12725 select on federated table crashes server
+# 
+#
+SET GLOBAL query_cache_size= 16*1024*1024;
+SET GLOBAL query_cache_type= 1;
+CREATE TABLE t1 (i INT);
+--replace_result $MASTER_MYPORT MASTER_MYPORT
+eval CREATE TABLE t2 (i INT) ENGINE=FEDERATED CONNECTION="mysql://root@localhost:$MASTER_MYPORT/test/t1";
+--error ER_ILLEGAL_HA
+ALTER TABLE t2 DISABLE KEYS;
+--replace_result $MASTER_MYPORT MASTER_MYPORT
+eval CREATE TABLE t3 (i INT) ENGINE=FEDERATED CONNECTION="mysql://root@localhost:$MASTER_MYPORT/test/t1";
+source include/restart_mysqld.inc;
+SET GLOBAL query_cache_size= default;
+SET GLOBAL query_cache_type= default;
+drop table t1, t2, t3;

storage/federatedx/federatedx_io_mysql.cc

@@ -120,6 +120,7 @@ class federatedx_io_mysql :public federatedx_io
                              void *ref);
   virtual int seek_position(FEDERATEDX_IO_RESULT **io_result,
                             const void *ref);
+  virtual void set_thd(void *thd);
 };
 
 
@@ -648,3 +649,7 @@ int federatedx_io_mysql::seek_position(FEDERATEDX_IO_RESULT **io_result,
   return 0;
 }
 
+void federatedx_io_mysql::set_thd(void *thd)
+{
+  mysql.net.thd= thd;
+}

storage/federatedx/federatedx_txn.cc

@@ -93,8 +93,8 @@ void federatedx_txn::close(FEDERATEDX_SERVER *server)
 }
 
 
-int federatedx_txn::acquire(FEDERATEDX_SHARE *share, bool readonly,
-                            federatedx_io **ioptr)
+int federatedx_txn::acquire(FEDERATEDX_SHARE *share, void *thd,
+                            bool readonly, federatedx_io **ioptr)
 {
   federatedx_io *io;
   FEDERATEDX_SERVER *server= share->s;
@@ -131,6 +131,7 @@ int federatedx_txn::acquire(FEDERATEDX_SHARE *share, bool readonly,
     
     io->busy= TRUE;
     io->owner_ptr= ioptr;
+    io->set_thd(thd);
   }
   
   DBUG_ASSERT(io->busy && io->server == server);
@@ -157,7 +158,10 @@ void federatedx_txn::release(federatedx_io **ioptr)
                 	io->active, io->is_autocommit()));
 
     if (io->is_autocommit())
+    {
+      io->set_thd(NULL);
       io->active= FALSE;
+    }
   }
 
   release_scan();

storage/federatedx/ha_federatedx.cc

@@ -1764,7 +1764,7 @@ int ha_federatedx::open(const char *name, int mode, uint test_if_locked)
 
   txn= get_txn(thd);
 
-  if ((error= txn->acquire(share, TRUE, &io)))
+  if ((error= txn->acquire(share, thd, TRUE, &io)))
   {
     free_share(txn, share);
     DBUG_RETURN(error);
@@ -2049,7 +2049,7 @@ int ha_federatedx::write_row(uchar *buf)
   /* we always want to append this, even if there aren't any fields */
   values_string.append(STRING_WITH_LEN(") "));
 
-  if ((error= txn->acquire(share, FALSE, &io)))
+  if ((error= txn->acquire(share, ha_thd(), FALSE, &io)))
     DBUG_RETURN(error);
 
   if (use_bulk_insert)
@@ -2138,7 +2138,7 @@ void ha_federatedx::start_bulk_insert(ha_rows rows, uint flags)
     Make sure we have an open connection so that we know the 
     maximum packet size.
   */
-  if (txn->acquire(share, FALSE, &io))
+  if (txn->acquire(share, ha_thd(), FALSE, &io))
     DBUG_VOID_RETURN;
 
   page_size= (uint) my_getpagesize();
@@ -2169,7 +2169,7 @@ int ha_federatedx::end_bulk_insert()
   
   if (bulk_insert.str && bulk_insert.length && !table_will_be_deleted)
   {
-    if ((error= txn->acquire(share, FALSE, &io)))
+    if ((error= txn->acquire(share, ha_thd(), FALSE, &io)))
       DBUG_RETURN(error);
     if (io->query(bulk_insert.str, bulk_insert.length))
       error= stash_remote_error();
@@ -2221,7 +2221,7 @@ int ha_federatedx::optimize(THD* thd, HA_CHECK_OPT* check_opt)
 
   DBUG_ASSERT(txn == get_txn(thd));
 
-  if ((error= txn->acquire(share, FALSE, &io)))
+  if ((error= txn->acquire(share, thd, FALSE, &io)))
     DBUG_RETURN(error);
 
   if (io->query(query.ptr(), query.length()))
@@ -2253,7 +2253,7 @@ int ha_federatedx::repair(THD* thd, HA_CHECK_OPT* check_opt)
 
   DBUG_ASSERT(txn == get_txn(thd));
 
-  if ((error= txn->acquire(share, FALSE, &io)))
+  if ((error= txn->acquire(share, thd, FALSE, &io)))
     DBUG_RETURN(error);
 
   if (io->query(query.ptr(), query.length()))
@@ -2412,7 +2412,7 @@ int ha_federatedx::update_row(const uchar *old_data, uchar *new_data)
   if (!has_a_primary_key)
     update_string.append(STRING_WITH_LEN(" LIMIT 1"));
 
-  if ((error= txn->acquire(share, FALSE, &io)))
+  if ((error= txn->acquire(share, ha_thd(), FALSE, &io)))
     DBUG_RETURN(error);
 
   if (io->query(update_string.ptr(), update_string.length()))
@@ -2490,7 +2490,7 @@ int ha_federatedx::delete_row(const uchar *buf)
   DBUG_PRINT("info",
              ("Delete sql: %s", delete_string.c_ptr_quick()));
 
-  if ((error= txn->acquire(share, FALSE, &io)))
+  if ((error= txn->acquire(share, ha_thd(), FALSE, &io)))
     DBUG_RETURN(error);
 
   if (io->query(delete_string.ptr(), delete_string.length()))
@@ -2599,7 +2599,7 @@ int ha_federatedx::index_read_idx_with_result_set(uchar *buf, uint index,
                         NULL, 0, 0);
   sql_query.append(index_string);
 
-  if ((retval= txn->acquire(share, TRUE, &io)))
+  if ((retval= txn->acquire(share, ha_thd(), TRUE, &io)))
     DBUG_RETURN(retval);
 
   if (io->query(sql_query.ptr(), sql_query.length()))
@@ -2679,7 +2679,7 @@ int ha_federatedx::read_range_first(const key_range *start_key,
                         &table->key_info[active_index],
                         start_key, end_key, 0, eq_range_arg);
 
-  if ((retval= txn->acquire(share, TRUE, &io)))
+  if ((retval= txn->acquire(share, ha_thd(), TRUE, &io)))
     DBUG_RETURN(retval);
 
   if (stored_result)
@@ -2779,7 +2779,7 @@ int ha_federatedx::rnd_init(bool scan)
   {
     int error;
 
-    if ((error= txn->acquire(share, TRUE, &io)))
+    if ((error= txn->acquire(share, ha_thd(), TRUE, &io)))
       DBUG_RETURN(error);
 
     if (stored_result)
@@ -2826,7 +2826,7 @@ int ha_federatedx::free_result()
   else
   {
     federatedx_io *tmp_io= 0, **iop;
-    if (!*(iop= &io) && (error= txn->acquire(share, TRUE, (iop= &tmp_io))))
+    if (!*(iop= &io) && (error= txn->acquire(share, ha_thd(), TRUE, (iop= &tmp_io))))
     {
       DBUG_ASSERT(0);                             // Fail when testing
       insert_dynamic(&results, (uchar*) &stored_result);
@@ -2906,7 +2906,7 @@ int ha_federatedx::read_next(uchar *buf, FEDERATEDX_IO_RESULT *result)
   FEDERATEDX_IO_ROW *row;
   DBUG_ENTER("ha_federatedx::read_next");
 
-  if ((retval= txn->acquire(share, TRUE, &io)))
+  if ((retval= txn->acquire(share, ha_thd(), TRUE, &io)))
     DBUG_RETURN(retval);
 
   /* Fetch a row, insert it back in a row format. */
@@ -2951,7 +2951,7 @@ void ha_federatedx::position(const uchar *record __attribute__ ((unused)))
     DBUG_VOID_RETURN;
   }
 
-  if (txn->acquire(share, TRUE, &io))
+  if (txn->acquire(share, ha_thd(), TRUE, &io))
     DBUG_VOID_RETURN;
 
   io->mark_position(stored_result, ref);
@@ -2980,7 +2980,7 @@ int ha_federatedx::rnd_pos(uchar *buf, uchar *pos)
   /* We have to move this to 'ref' to get things aligned */
   bmove(ref, pos, ref_length);
 
-  if ((retval= txn->acquire(share, TRUE, &io)))
+  if ((retval= txn->acquire(share, ha_thd(), TRUE, &io)))
     goto error;
 
   if ((retval= io->seek_position(&result, ref)))
@@ -3054,7 +3054,7 @@ int ha_federatedx::info(uint flag)
   /* we want not to show table status if not needed to do so */
   if (flag & (HA_STATUS_VARIABLE | HA_STATUS_CONST | HA_STATUS_AUTO))
   {
-    if (!*(iop= &io) && (error_code= tmp_txn->acquire(share, TRUE, (iop= &tmp_io))))
+    if (!*(iop= &io) && (error_code= tmp_txn->acquire(share, thd, TRUE, (iop= &tmp_io))))
       goto fail;
   }
 
@@ -3155,6 +3155,7 @@ int ha_federatedx::extra(ha_extra_function operation)
 
 int ha_federatedx::reset(void)
 {
+  THD *thd= ha_thd();
   int error = 0;
 
   insert_dup_update= FALSE;
@@ -3172,9 +3173,9 @@ int ha_federatedx::reset(void)
     federatedx_io *tmp_io= 0, **iop;
 
     // external_lock may not have been called so txn may not be set
-    tmp_txn= get_txn(ha_thd());
+    tmp_txn= get_txn(thd);
 
-    if (!*(iop= &io) && (error= tmp_txn->acquire(share, TRUE, (iop= &tmp_io))))
+    if (!*(iop= &io) && (error= tmp_txn->acquire(share, thd, TRUE, (iop= &tmp_io))))
     {
       DBUG_ASSERT(0);                             // Fail when testing
       return error;
@@ -3208,6 +3209,7 @@ int ha_federatedx::reset(void)
 
 int ha_federatedx::delete_all_rows()
 {
+  THD *thd= ha_thd();
   char query_buffer[FEDERATEDX_QUERY_BUFFER_SIZE];
   String query(query_buffer, sizeof(query_buffer), &my_charset_bin);
   int error;
@@ -3221,14 +3223,14 @@ int ha_federatedx::delete_all_rows()
                ident_quote_char);
 
   /* no need for savepoint in autocommit mode */
-  if (!(ha_thd()->variables.option_bits & (OPTION_NOT_AUTOCOMMIT | OPTION_BEGIN)))
+  if (!(thd->variables.option_bits & (OPTION_NOT_AUTOCOMMIT | OPTION_BEGIN)))
     txn->stmt_autocommit();
 
   /*
     TRUNCATE won't return anything in mysql_affected_rows
   */
 
-  if ((error= txn->acquire(share, FALSE, &io)))
+  if ((error= txn->acquire(share, thd, FALSE, &io)))
     DBUG_RETURN(error);
 
   if (io->query(query.ptr(), query.length()))
@@ -3373,7 +3375,7 @@ int ha_federatedx::create(const char *name, TABLE *table_arg,
   if (tmp_share.s)
   {
     tmp_txn= get_txn(thd);
-    if (!(retval= tmp_txn->acquire(&tmp_share, TRUE, &tmp_io)))
+    if (!(retval= tmp_txn->acquire(&tmp_share, thd, TRUE, &tmp_io)))
     {
       retval= test_connection(thd, tmp_io, &tmp_share);
       tmp_txn->release(&tmp_io);
@@ -3470,7 +3472,7 @@ int ha_federatedx::external_lock(MYSQL_THD thd, int lock_type)
   {
     table_will_be_deleted = FALSE;
     txn= get_txn(thd);  
-    if (!(error= txn->acquire(share, lock_type == F_RDLCK, &io)) &&
+    if (!(error= txn->acquire(share, ha_thd(), lock_type == F_RDLCK, &io)) &&
         (lock_type == F_WRLCK || !io->is_autocommit()))
     {
       if (!thd_test_options(thd, (OPTION_NOT_AUTOCOMMIT | OPTION_BEGIN)))

storage/federatedx/ha_federatedx.h

@@ -215,6 +215,7 @@ class federatedx_io
                              void *ref)=0;
   virtual int seek_position(FEDERATEDX_IO_RESULT **io_result,
                             const void *ref)=0;
+  virtual void set_thd(void *thd) { }
 
 };
 
@@ -233,7 +234,7 @@ class federatedx_txn
 
   bool has_connections() const { return txn_list != NULL; }
   bool in_transaction() const { return savepoint_next != 0; }
-  int acquire(FEDERATEDX_SHARE *share, bool readonly, federatedx_io **io);
+  int acquire(FEDERATEDX_SHARE *share, void *thd, bool readonly, federatedx_io **io);
   void release(federatedx_io **io);
   void close(FEDERATEDX_SERVER *);