MDEV-14786: Server crashes in Item_cond::transform on 2nd execution of SP querying from a view

MDEV-14957: JOIN::prepare gets unusable "conds" as argument

Do not touch merged derived (it is irreversible)

Fix first argument of in_optimizer for calls possible before fix_fields()

mysql-test/r/derived.result

@@ -1036,4 +1036,20 @@ SELECT * FROM v1, t2, v3 WHERE a = c AND b = d;
 a	b	c	d
 DROP VIEW v1, v3;
 DROP TABLE t1, t2, t3;
+#
+# MDEV-14786: Server crashes in Item_cond::transform on 2nd
+# execution of SP querying from a view
+#
+create table t1 (i int, row_start timestamp(6) not null default now(),
+row_end timestamp(6) not null default '2030-01-01 0:0:0');
+create view v1 as select i from t1 where i < 5 and (row_end =
+TIMESTAMP'2030-01-01 0:0:0' or row_end is null);
+create procedure pr(x int) select i from v1;
+call pr(1);
+i
+call pr(2);
+i
+drop procedure pr;
+drop view v1;
+drop table t1;
 # end of 5.5

mysql-test/t/derived.test

@@ -888,4 +888,19 @@ SELECT * FROM v1, t2, v3 WHERE a = c AND b = d;
 DROP VIEW v1, v3;
 DROP TABLE t1, t2, t3;
 
+--echo #
+--echo # MDEV-14786: Server crashes in Item_cond::transform on 2nd
+--echo # execution of SP querying from a view
+--echo #
+create table t1 (i int, row_start timestamp(6) not null default now(),
+                 row_end timestamp(6) not null default '2030-01-01 0:0:0');
+create view v1 as select i from t1 where i < 5 and (row_end =
+TIMESTAMP'2030-01-01 0:0:0' or row_end is null);
+create procedure pr(x int) select i from v1;
+call pr(1);
+call pr(2);
+drop procedure pr;
+drop view v1;
+drop table t1;
+
 --echo # end of 5.5

sql/item.cc

@@ -10010,7 +10010,7 @@ const char *dbug_print_item(Item *item)
   if (!item)
     return "(Item*)NULL";
   item->print(&str ,QT_ORDINARY);
-  if (str.c_ptr() == buf)
+  if (str.c_ptr_safe() == buf)
     return buf;
   else
     return "Couldn't fit into buffer";

sql/item.h

@@ -50,6 +50,12 @@ bool trace_unsupported_by_check_vcol_func_processor(const char *where)
   return trace_unsupported_func(where, "check_vcol_func_processor");
 }
 
+#ifdef DBUG_OFF
+static inline const char *dbug_print_item(Item *item) { return NULL; }
+#else
+extern const char *dbug_print_item(Item *item);
+#endif
+
 class Protocol;
 struct TABLE_LIST;
 void item_init(void);			/* Init item functions */

sql/item_cmpfunc.cc

@@ -1420,6 +1420,7 @@ bool Item_in_optimizer::is_top_level_item()
 
 void Item_in_optimizer::fix_after_pullout(st_select_lex *new_parent, Item **ref)
 {
+  DBUG_ASSERT(fixed);
   /* This will re-calculate attributes of our Item_in_subselect: */
   Item_bool_func::fix_after_pullout(new_parent, ref);
 
@@ -1443,6 +1444,33 @@ bool Item_in_optimizer::eval_not_null_tables(uchar *opt_arg)
 }
 
 
+void Item_in_optimizer::print(String *str, enum_query_type query_type)
+{
+   restore_first_argumet();
+   Item_func::print(str, query_type);
+}
+
+
+/**
+  "Restore" first argument before fix_fields() call (after it is harmless).
+
+  @Note: Main pointer to left part of IN/ALL/ANY subselect is subselect's
+  lest_expr (see Item_in_optimizer::fix_left) so changes made during
+  fix_fields will be rolled back there which can make
+  Item_in_optimizer::args[0] unusable on second execution before fix_left()
+  call. This call fix the pointer.
+*/
+
+void Item_in_optimizer::restore_first_argumet()
+{
+  if (args[1]->type() == Item::SUBSELECT_ITEM &&
+      ((Item_subselect *)args[1])->is_in_predicate())
+  {
+    args[0]= ((Item_in_subselect *)args[1])->left_expr;
+  }
+}
+
+
 bool Item_in_optimizer::fix_left(THD *thd, Item **ref)
 {
   DBUG_ENTER("Item_in_optimizer::fix_left");
@@ -1588,6 +1616,8 @@ Item *Item_in_optimizer::expr_cache_insert_transformer(uchar *thd_arg)
 {
   THD *thd= (THD*) thd_arg;
   DBUG_ENTER("Item_in_optimizer::expr_cache_insert_transformer");
+  DBUG_ASSERT(fixed);
+
   if (args[1]->type() != Item::SUBSELECT_ITEM)
     DBUG_RETURN(this); // MAX/MIN transformed => do nothing
 
@@ -1611,6 +1641,7 @@ Item *Item_in_optimizer::expr_cache_insert_transformer(uchar *thd_arg)
 
 void Item_in_optimizer::get_cache_parameters(List<Item> &parameters)
 {
+  DBUG_ASSERT(fixed);
   /* Add left expression to the list of the parameters of the subquery */
   if (args[0]->cols() == 1)
     parameters.add_unique(args[0], &cmp_items);
@@ -1842,6 +1873,7 @@ Item *Item_in_optimizer::transform(Item_transformer transformer, uchar *argument
 {
   Item *new_item;
 
+  DBUG_ASSERT(fixed);
   DBUG_ASSERT(!current_thd->stmt_arena->is_stmt_prepare());
   DBUG_ASSERT(arg_count == 2);
 
@@ -1893,6 +1925,7 @@ Item *Item_in_optimizer::transform(Item_transformer transformer, uchar *argument
 
 bool Item_in_optimizer::is_expensive_processor(uchar *arg)
 {
+  DBUG_ASSERT(fixed);
   return args[0]->is_expensive_processor(arg) ||
          args[1]->is_expensive_processor(arg);
 }
@@ -1900,6 +1933,7 @@ bool Item_in_optimizer::is_expensive_processor(uchar *arg)
 
 bool Item_in_optimizer::is_expensive()
 {
+  DBUG_ASSERT(fixed);
   return args[0]->is_expensive() || args[1]->is_expensive();
 }
 

sql/item_cmpfunc.h

@@ -268,6 +268,8 @@ public:
   bool is_top_level_item();
   bool eval_not_null_tables(uchar *opt_arg);
   void fix_after_pullout(st_select_lex *new_parent, Item **ref);
+  virtual void print(String *str, enum_query_type query_type);
+  void restore_first_argumet();
 };
 
 class Comp_creator

sql/sql_derived.cc

@@ -366,7 +366,11 @@ bool mysql_derived_merge(THD *thd, LEX *lex, TABLE_LIST *derived)
                        derived->get_unit()));
 
   if (derived->merged)
+  {
+
+    DBUG_PRINT("info", ("Irreversibly merged: exit"));
     DBUG_RETURN(FALSE);
+  }
 
   if (dt_select->uncacheable & UNCACHEABLE_RAND)
   {
@@ -667,6 +671,17 @@ bool mysql_derived_prepare(THD *thd, LEX *lex, TABLE_LIST *derived)
 
   unit->derived= derived;
 
+  /*
+    Above cascade call of prepare is important for PS protocol, but after it
+    is called we can check if we really need prepare for this derived
+  */
+  if (derived->merged)
+  {
+    DBUG_PRINT("info", ("Irreversibly merged: exit"));
+    DBUG_RETURN(FALSE);
+  }
+
+
   derived->fill_me= FALSE;
 
   if (!(derived->derived_result= new select_union))
@@ -795,6 +810,11 @@ bool mysql_derived_optimize(THD *thd, LEX *lex, TABLE_LIST *derived)
   DBUG_PRINT("enter", ("Alias: '%s'  Unit: %p",
                        (derived->alias ? derived->alias : "<NULL>"),
                        derived->get_unit()));
+  if (derived->merged)
+  {
+    DBUG_PRINT("info", ("Irreversibly merged: exit"));
+    DBUG_RETURN(FALSE);
+  }
 
   if (unit->optimized)
     DBUG_RETURN(FALSE);

sql/sql_select.cc

@@ -638,6 +638,9 @@ JOIN::prepare(Item ***rref_pointer_array,
   join_list= &select_lex->top_join_list;
   union_part= unit_arg->is_union();
 
+  // simple check that we got usable conds
+  dbug_print_item(conds);
+
   if (select_lex->handle_derived(thd->lex, DT_PREPARE))
     DBUG_RETURN(1);