MDEV-11780 Crash with PREPARE + SP out parameter + literal

Before "MDEV-10709 Expressions as parameters to Dynamic SQL" only
user variables were syntactically allowed as EXECUTE parameters.
User variables were OK as both IN and OUT parameters.
When Item_param was bound to an actual parameter (a user variable),
it automatically meant that the bound Item was settable.
The DBUG_ASSERT() in Protocol_text::send_out_parameters() guarded that
the actual parameter is really settable.

After MDEV-10709, any kind of expressions are allowed as EXECUTE IN parameters.
But the patch for MDEV-10709 forgot to check that only descendants of
Settable_routine_parameter should be allowed as OUT parameters.
So an attempt to pass a non-settable parameter as an OUT parameter
made server crash on the above mentioned DBUG_ASSERT.

This patch changes Item_param::get_settable_routine_parameter(),
which previously always returned "this". Now, when Item_param is bound
to some Item, it caches if the bound Item is settable.
Item_param::get_settable_routine_parameter() now returns "this" only
if the bound actual parameter is settable, and returns NULL otherwise.

mysql-test/r/ps.result

@@ -4747,3 +4747,26 @@ INSERT INTO t1 VALUES (1),(2),(3);
 EXECUTE IMMEDIATE 'EXPLAIN EXTENDED SELECT * FROM t1 WHERE ?+a<=>?+a' USING DEFAULT,DEFAULT;
 ERROR HY000: Default/ignore value is not supported for such parameter usage
 DROP TABLE t1;
+#
+# MDEV-11780 Crash with PREPARE + SP out parameter + literal
+#
+CREATE OR REPLACE PROCEDURE p1(OUT a INT)
+BEGIN
+SET a=10;
+END;
+$$
+PREPARE stmt FROM 'CALL p1(?)';
+EXECUTE stmt USING 10;
+ERROR 42000: OUT or INOUT argument 1 for routine test.p1 is not a variable or NEW pseudo-variable in BEFORE trigger
+EXECUTE stmt USING DEFAULT;
+ERROR 42000: OUT or INOUT argument 1 for routine test.p1 is not a variable or NEW pseudo-variable in BEFORE trigger
+EXECUTE stmt USING IGNORE;
+ERROR 42000: OUT or INOUT argument 1 for routine test.p1 is not a variable or NEW pseudo-variable in BEFORE trigger
+DEALLOCATE PREPARE stmt;
+EXECUTE IMMEDIATE 'CALL p1(?)' USING 10;
+ERROR 42000: OUT or INOUT argument 1 for routine test.p1 is not a variable or NEW pseudo-variable in BEFORE trigger
+EXECUTE IMMEDIATE 'CALL p1(?)' USING DEFAULT;
+ERROR 42000: OUT or INOUT argument 1 for routine test.p1 is not a variable or NEW pseudo-variable in BEFORE trigger
+EXECUTE IMMEDIATE 'CALL p1(?)' USING IGNORE;
+ERROR 42000: OUT or INOUT argument 1 for routine test.p1 is not a variable or NEW pseudo-variable in BEFORE trigger
+DROP PROCEDURE p1;

mysql-test/t/ps.test

@@ -4287,3 +4287,32 @@ INSERT INTO t1 VALUES (1),(2),(3);
 --error ER_INVALID_DEFAULT_PARAM
 EXECUTE IMMEDIATE 'EXPLAIN EXTENDED SELECT * FROM t1 WHERE ?+a<=>?+a' USING DEFAULT,DEFAULT;
 DROP TABLE t1;
+
+--echo #
+--echo # MDEV-11780 Crash with PREPARE + SP out parameter + literal
+--echo #
+
+DELIMITER $$;
+CREATE OR REPLACE PROCEDURE p1(OUT a INT)
+BEGIN
+  SET a=10;
+END;
+$$
+DELIMITER ;$$
+
+PREPARE stmt FROM 'CALL p1(?)';
+--error ER_SP_NOT_VAR_ARG
+EXECUTE stmt USING 10;
+--error ER_SP_NOT_VAR_ARG
+EXECUTE stmt USING DEFAULT;
+--error ER_SP_NOT_VAR_ARG
+EXECUTE stmt USING IGNORE;
+DEALLOCATE PREPARE stmt;
+
+--error ER_SP_NOT_VAR_ARG
+EXECUTE IMMEDIATE 'CALL p1(?)' USING 10;
+--error ER_SP_NOT_VAR_ARG
+EXECUTE IMMEDIATE 'CALL p1(?)' USING DEFAULT;
+--error ER_SP_NOT_VAR_ARG
+EXECUTE IMMEDIATE 'CALL p1(?)' USING IGNORE;
+DROP PROCEDURE p1;

sql/item.cc

@@ -3313,7 +3313,15 @@ Item_param::Item_param(THD *thd, uint pos_in_query_arg):
   item_type(PARAM_ITEM),
   indicators(0), indicator(STMT_INDICATOR_NONE),
   set_param_func(default_set_param_func),
-  m_out_param_info(NULL)
+  m_out_param_info(NULL),
+  /*
+    Set m_is_settable_routine_parameter to "true" by default.
+    This is needed for client-server protocol,
+    whose parameters are always settable.
+    For dynamic SQL, settability depends on the type of Item passed
+    as an actual parameter. See Item_param::set_from_item().
+  */
+  m_is_settable_routine_parameter(true)
 {
   name= (char*) "?";
   /* 
@@ -3557,6 +3565,7 @@ bool Item_param::CONVERSION_INFO::convert(THD *thd, String *str)
 bool Item_param::set_from_item(THD *thd, Item *item)
 {
   DBUG_ENTER("Item_param::set_from_item");
+  m_is_settable_routine_parameter= item->get_settable_routine_parameter();
   if (limit_clause_param)
   {
     longlong val= item->val_int();
@@ -4132,6 +4141,7 @@ Item_param::set_param_type_and_swap_value(Item_param *src)
 
 void Item_param::set_default()
 {
+  m_is_settable_routine_parameter= false;
   state= DEFAULT_VALUE;
   fixed= true;
   /*
@@ -4147,6 +4157,7 @@ void Item_param::set_default()
 
 void Item_param::set_ignore()
 {
+  m_is_settable_routine_parameter= false;
   state= IGNORE_VALUE;
   fixed= true;
   null_value= true;

sql/item.h

@@ -2982,7 +2982,7 @@ class Item_param :public Item_basic_value,
   Rewritable_query_parameter *get_rewritable_query_parameter()
   { return this; }
   Settable_routine_parameter *get_settable_routine_parameter()
-  { return this; }
+  { return m_is_settable_routine_parameter ? this : NULL; }
 
   bool append_for_log(THD *thd, String *str);
   bool check_vcol_func_processor(void *int_arg) {return FALSE;}
@@ -3002,6 +3002,7 @@ class Item_param :public Item_basic_value,
 
 private:
   Send_field *m_out_param_info;
+  bool m_is_settable_routine_parameter;
 };