Bug#47627 SET @@{global.session}.local_variable in stored routine causes crash

This patch borrows ideas, text and code from Kristofer
Pettersson's patch.

An assignment of a system variable sharing the same base
name as a declared stored procedure variable in the same
context could lead to a crash.

The reason was that during the parsing of the syntactic
rule 'option_value' an uninitialized set_var object was
pushed to the parameter stack of the SET statement. The
parent rule 'option_type_value' interpreted the existence
of variables on the parameter stack as an assignment and
wrapped it in a sp_instr_set object.

As the procedure later was executed an attempt was made
to run the method 'check()' on an uninitialized member
object (NULL value) belonging to the previously created
but uninitialized object.

This patch refactors the 'internal_variable_name' rule and
copies the semantic analysis part to the depending parent
rule: 'option_value'. This makes it possible to account
for any prefixes affecting the interpretation of the
internal_variable_name.

mysql-test/r/sp.result:
  Add test case result.
mysql-test/t/sp.test:
  Add test case for bug.
sql/sql_yacc.yy:
  - Reduce churn in rule sys_option_value by moving to
    specialized functions.
  - Comment the the lookup in the rule internel_variable_name
    is a best effort operation.
  - Lookup for a system variable in the option_value if one was
    not found (the variable could have been shadowed)

2 files changed, 125 insertions, 0 deletions

diff --git a/mysql-test/r/sp.result b/mysql-test/r/sp.result
index 67514c314f4..83ad7545685 100644
--- a/mysql-test/r/sp.result
+++ b/mysql-test/r/sp.result
@@ -6979,6 +6979,64 @@ CALL p1;
 ERROR 42S22: Unknown column 'A.b' in 'IN/ALL/ANY subquery'
 DROP PROCEDURE p1;
 DROP TABLE t1, t2;
+#
+# Bug#47627: SET @@{global.session}.local_variable in stored routine causes crash
+# Bug#48626: Crash or lost connection using SET for declared variables with @@
+#
+DROP PROCEDURE IF EXISTS p1;
+DROP PROCEDURE IF EXISTS p2;
+DROP PROCEDURE IF EXISTS p3;
+CREATE PROCEDURE p1()
+BEGIN
+DECLARE v INT DEFAULT 0;
+SET @@SESSION.v= 10;
+END//
+ERROR HY000: Unknown system variable 'v'
+CREATE PROCEDURE p2()
+BEGIN
+DECLARE v INT DEFAULT 0;
+SET v= 10;
+END//
+call p2()//
+CREATE PROCEDURE p3()
+BEGIN
+DECLARE v INT DEFAULT 0;
+SELECT @@SESSION.v;
+END//
+ERROR HY000: Unknown system variable 'v'
+CREATE PROCEDURE p4()
+BEGIN
+DECLARE v INT DEFAULT 0;
+SET @@GLOBAL.v= 10;
+END//
+ERROR HY000: Unknown system variable 'v'
+CREATE PROCEDURE p5()
+BEGIN
+DECLARE init_connect INT DEFAULT 0;
+SET init_connect= 10;
+SET @@GLOBAL.init_connect= 'SELECT 1';
+SET @@SESSION.IDENTITY= 1;
+SELECT @@SESSION.IDENTITY;
+SELECT @@GLOBAL.init_connect;
+SELECT init_connect;
+END//
+CREATE PROCEDURE p6()
+BEGIN
+DECLARE v INT DEFAULT 0;
+SET @@v= 0;
+END//
+ERROR HY000: Unknown system variable 'v'
+SET @old_init_connect= @@GLOBAL.init_connect;
+CALL p5();
+@@SESSION.IDENTITY
+1
+@@GLOBAL.init_connect
+SELECT 1
+init_connect
+10
+SET @@GLOBAL.init_connect= @old_init_connect;
+DROP PROCEDURE p2;
+DROP PROCEDURE p5;
 # ------------------------------------------------------------------
 # -- End of 5.1 tests
 # ------------------------------------------------------------------
diff --git a/mysql-test/t/sp.test b/mysql-test/t/sp.test
index 44c4556340e..73ba62612b8 100644
--- a/mysql-test/t/sp.test
+++ b/mysql-test/t/sp.test
@@ -8263,6 +8263,73 @@ CALL p1;
 DROP PROCEDURE p1;
 DROP TABLE t1, t2;
 
+--echo #
+--echo # Bug#47627: SET @@{global.session}.local_variable in stored routine causes crash
+--echo # Bug#48626: Crash or lost connection using SET for declared variables with @@
+--echo #
+
+--disable_warnings
+DROP PROCEDURE IF EXISTS p1;
+DROP PROCEDURE IF EXISTS p2;
+DROP PROCEDURE IF EXISTS p3;
+--enable_warnings
+
+delimiter //;
+
+--error ER_UNKNOWN_SYSTEM_VARIABLE
+CREATE PROCEDURE p1()
+BEGIN
+  DECLARE v INT DEFAULT 0;
+  SET @@SESSION.v= 10;
+END//
+
+CREATE PROCEDURE p2()
+BEGIN
+  DECLARE v INT DEFAULT 0;
+  SET v= 10;
+END//
+call p2()//
+
+--error ER_UNKNOWN_SYSTEM_VARIABLE
+CREATE PROCEDURE p3()
+BEGIN
+  DECLARE v INT DEFAULT 0;
+  SELECT @@SESSION.v;
+END//
+
+--error ER_UNKNOWN_SYSTEM_VARIABLE
+CREATE PROCEDURE p4()
+BEGIN
+  DECLARE v INT DEFAULT 0;
+  SET @@GLOBAL.v= 10;
+END//
+
+CREATE PROCEDURE p5()
+BEGIN
+  DECLARE init_connect INT DEFAULT 0;
+  SET init_connect= 10;
+  SET @@GLOBAL.init_connect= 'SELECT 1';
+  SET @@SESSION.IDENTITY= 1;
+  SELECT @@SESSION.IDENTITY;
+  SELECT @@GLOBAL.init_connect;
+  SELECT init_connect;
+END//
+
+--error ER_UNKNOWN_SYSTEM_VARIABLE
+CREATE PROCEDURE p6()
+BEGIN
+  DECLARE v INT DEFAULT 0;
+  SET @@v= 0;
+END//
+
+delimiter ;//
+
+SET @old_init_connect= @@GLOBAL.init_connect;
+CALL p5();
+SET @@GLOBAL.init_connect= @old_init_connect;
+
+DROP PROCEDURE p2;
+DROP PROCEDURE p5;
 
 --echo # ------------------------------------------------------------------
 --echo # -- End of 5.1 tests