"Fix" for bug #11394 "Recursion in SP crash server" and bug #11600

"Stored procedures: crash with function calling itself".

Disallow recursive stored routines until we either make Item's and LEX
reentrant safe or will use spearate sp_head instances (and thus separate
LEX objects and Item trees) for each routine invocation.


mysql-test/r/sp-error.result:
  Added tests for bug #11394 "Recursion in SP crash server" and
  bug #11600 "Stored procedures: crash with function calling itself".
  (We simply disallow recursion for stored routines).
mysql-test/r/sp.result:
  Disabled test cases containing recursive stored routines until we will
  support for them.
mysql-test/t/sp-error.test:
  Added tests for bug #11394 "Recursion in SP crash server" and
  bug #11600 "Stored procedures: crash with function calling itself".
  (We simply disallow recursion for stored routines).
mysql-test/t/sp.test:
  Disabled test cases containing recursive stored routines until we will
  support for them.
sql/share/errmsg.txt:
  Added error message saying that recursive stored routines are disallowed.
sql/sp_head.cc:
  sp_head::execute():
    Since many Item's and LEX members can't be used in reentrant fashion
    we have to disable recursion for stored routines. So let us track
    routine invocations using sp_head::m_is_invoked member and raise
    error when one attempts to call routine recursively.
sql/sp_head.h:
  sp_head:
    Added m_is_invoked member for tracking of routine invocations and
    preventing recursion.

mysql-test/r/sp-error.result

@@ -686,3 +686,43 @@ ERROR 0A000: EXECUTE is not allowed in stored procedures
 create function f() returns int begin execute stmt;
 ERROR 0A000: EXECUTE is not allowed in stored procedures
 deallocate prepare stmt;
+drop function if exists bug11394|
+drop function if exists bug11394_1|
+drop function if exists bug11394_2|
+drop procedure if exists bug11394|
+create function bug11394(i int) returns int
+begin
+if i <= 0 then
+return 0;
+else
+return (i in (100, 200, bug11394(i-1), 400));
+end if;
+end|
+select bug11394(2)|
+ERROR HY000: Recursive stored routines are not allowed.
+drop function bug11394|
+create function bug11394_1(i int) returns int
+begin
+if i <= 0 then
+return 0;
+else
+return (select bug11394_1(i-1));
+end if;
+end|
+select bug11394_1(2)|
+ERROR HY000: Recursive stored routines are not allowed.
+drop function bug11394_1|
+create function bug11394_2(i int) returns int return i|
+select bug11394_2(bug11394_2(10))|
+bug11394_2(bug11394_2(10))
+10
+drop function bug11394_2|
+create procedure bug11394(i int, j int)
+begin
+if i > 0 then
+call bug11394(i - 1,(select 1));
+end if;
+end|
+call bug11394(2, 1)|
+ERROR HY000: Recursive stored routines are not allowed.
+drop procedure bug11394|

mysql-test/r/sp.result

@@ -1396,60 +1396,6 @@ drop procedure opp|
 drop procedure ip|
 show procedure status like '%p%'|
 Db	Name	Type	Definer	Modified	Created	Security_type	Comment
-drop table if exists fib|
-create table fib ( f bigint unsigned not null )|
-drop procedure if exists fib|
-create procedure fib(n int unsigned)
-begin
-if n > 1 then
-begin
-declare x, y bigint unsigned;
-declare c cursor for select f from fib order by f desc limit 2;
-open c;
-fetch c into y;
-fetch c into x;
-close c;
-insert into fib values (x+y);
-call fib(n-1);
-end;
-end if;
-end|
-insert into fib values (0), (1)|
-call fib(3)|
-select * from fib order by f asc|
-f
-0
-1
-1
-2
-delete from fib|
-insert into fib values (0), (1)|
-call fib(20)|
-select * from fib order by f asc|
-f
-0
-1
-1
-2
-3
-5
-8
-13
-21
-34
-55
-89
-144
-233
-377
-610
-987
-1597
-2584
-4181
-6765
-drop table fib|
-drop procedure fib|
 drop procedure if exists bar|
 create procedure bar(x char(16), y int)
 comment "111111111111" sql security invoker
@@ -2506,20 +2452,6 @@ s1
 1
 drop procedure bug4905|
 drop table t3|
-drop function if exists bug6022|
-drop function if exists bug6022|
-create function bug6022(x int) returns int
-begin
-if x < 0 then
-return 0;
-else
-return bug6022(x-1);
-end if;
-end|
-select bug6022(5)|
-bug6022(5)
-0
-drop function bug6022|
 drop procedure if exists bug6029|
 drop procedure if exists bug6029|
 create procedure bug6029()

mysql-test/t/sp-error.test

@@ -986,3 +986,58 @@ create procedure p() execute stmt;
 create function f() returns int begin execute stmt;
 deallocate prepare stmt;
 
+#
+# Bug #11394 "Recursion in SP crash server" and bug #11600 "Stored
+# procedures: crash with function calling itself".
+# We have to disable recursion since in many cases LEX and many
+# Item's can't be used in reentrant way nowdays.
+delimiter |;
+--disable_warnings
+drop function if exists bug11394|
+drop function if exists bug11394_1|
+drop function if exists bug11394_2|
+drop procedure if exists bug11394|
+--enable_warnings
+create function bug11394(i int) returns int
+begin
+  if i <= 0 then
+    return 0;
+  else
+    return (i in (100, 200, bug11394(i-1), 400));
+  end if;
+end|
+# If we allow recursive functions without additional modifications
+# this will crash server since Item for "IN" is not reenterable.
+--error 1423
+select bug11394(2)|
+drop function bug11394|
+create function bug11394_1(i int) returns int
+begin
+  if i <= 0 then
+    return 0;
+  else
+    return (select bug11394_1(i-1));
+  end if;
+end|
+# The following statement will crash because some LEX members responsible
+# for selects cannot be used in reentrant fashion.
+--error 1423
+select bug11394_1(2)|
+drop function bug11394_1|
+# Note that the following should be allowed since it does not contains
+# recursion
+create function bug11394_2(i int) returns int return i|
+select bug11394_2(bug11394_2(10))|
+drop function bug11394_2|
+create procedure bug11394(i int, j int)
+begin
+  if i > 0 then
+    call bug11394(i - 1,(select 1));
+  end if;
+end|
+# Again if we allow recursion for stored procedures (without 
+# additional efforts) the following statement will crash the server.
+--error 1423
+call bug11394(2, 1)|
+drop procedure bug11394|
+delimiter |;

mysql-test/t/sp.test

@@ -1630,54 +1630,56 @@ show procedure status like '%p%'|
 
 
 # Fibonacci, for recursion test. (Yet Another Numerical series :)
-
---disable_warnings
-drop table if exists fib|
---enable_warnings
-create table fib ( f bigint unsigned not null )|
-
-# We deliberately do it the awkward way, fetching the last two
-# values from the table, in order to exercise various statements
-# and table accesses at each turn.
---disable_warnings
-drop procedure if exists fib|
---enable_warnings
-create procedure fib(n int unsigned)
-begin
-  if n > 1 then
-    begin
-      declare x, y bigint unsigned;
-      declare c cursor for select f from fib order by f desc limit 2;
-
-      open c;
-      fetch c into y;
-      fetch c into x;
-      close c;
-      insert into fib values (x+y);
-      call fib(n-1);
-    end;
-  end if;
-end|
-
-# Minimum test: recursion of 3 levels
-
-insert into fib values (0), (1)|
-
-call fib(3)|
-
-select * from fib order by f asc|
-
-delete from fib|
-
-# Original test: 20 levels (may run into memory limits!)
-
-insert into fib values (0), (1)|
-
-call fib(20)|
-
-select * from fib order by f asc|
-drop table fib|
-drop procedure fib|
+#
+# This part of test is disabled until we implement support for
+# recursive stored procedures.
+#--disable_warnings
+#drop table if exists fib|
+#--enable_warnings
+#create table fib ( f bigint unsigned not null )|
+#
+## We deliberately do it the awkward way, fetching the last two
+## values from the table, in order to exercise various statements
+## and table accesses at each turn.
+#--disable_warnings
+#drop procedure if exists fib|
+#--enable_warnings
+#create procedure fib(n int unsigned)
+#begin
+#  if n > 1 then
+#    begin
+#      declare x, y bigint unsigned;
+#      declare c cursor for select f from fib order by f desc limit 2;
+#
+#      open c;
+#      fetch c into y;
+#      fetch c into x;
+#      close c;
+#      insert into fib values (x+y);
+#      call fib(n-1);
+#    end;
+#  end if;
+#end|
+#
+## Minimum test: recursion of 3 levels
+#
+#insert into fib values (0), (1)|
+#
+#call fib(3)|
+#
+#select * from fib order by f asc|
+#
+#delete from fib|
+#
+## Original test: 20 levels (may run into memory limits!)
+#
+#insert into fib values (0), (1)|
+#
+#call fib(20)|
+#
+#select * from fib order by f asc|
+#drop table fib|
+#drop procedure fib|
 
 
 #
@@ -3011,24 +3013,26 @@ drop table t3|
 #
 # BUG#6022: Stored procedure shutdown problem with self-calling function.
 #
---disable_warnings
-drop function if exists bug6022|
---enable_warnings
-
---disable_warnings
-drop function if exists bug6022|
---enable_warnings
-create function bug6022(x int) returns int
-begin
-  if x < 0 then
-    return 0;
-  else
-    return bug6022(x-1);
-  end if;
-end|
-
-select bug6022(5)|
-drop function bug6022|
+# This part of test is disabled until we implement support for
+# recursive stored functions.
+#--disable_warnings
+#drop function if exists bug6022|
+#--enable_warnings
+#
+#--disable_warnings
+#drop function if exists bug6022|
+#--enable_warnings
+#create function bug6022(x int) returns int
+#begin
+#  if x < 0 then
+#    return 0;
+#  else
+#    return bug6022(x-1);
+#  end if;
+#end|
+#
+#select bug6022(5)|
+#drop function bug6022|
 
 #
 # BUG#6029: Stored procedure specific handlers should have priority

sql/share/errmsg.txt

@@ -5358,3 +5358,5 @@ ER_STMT_HAS_NO_OPEN_CURSOR
 	eng "The statement (%lu) has no open cursor."
 ER_COMMIT_NOT_ALLOWED_IN_SF_OR_TRG
         eng "Explicit or implicit commit is not allowed in stored function or trigger."
+ER_SP_NO_RECURSION
+        eng "Recursive stored routines are not allowed."

sql/sp_head.cc

@@ -312,7 +312,8 @@ sp_head::operator delete(void *ptr, size_t size)
 sp_head::sp_head()
   :Query_arena(&main_mem_root, INITIALIZED_FOR_SP),
    m_returns_cs(NULL), m_has_return(FALSE),
-   m_simple_case(FALSE), m_multi_results(FALSE), m_in_handler(FALSE)
+   m_simple_case(FALSE), m_multi_results(FALSE), m_in_handler(FALSE),
+   m_is_invoked(FALSE)
 {
   extern byte *
     sp_table_key(const byte *ptr, uint *plen, my_bool first);
@@ -587,6 +588,28 @@ sp_head::execute(THD *thd)
     DBUG_RETURN(-1);
   }
 
+  if (m_is_invoked)
+  {
+    /*
+      We have to disable recursion for stored routines since in
+      many cases LEX structure and many Item's can't be used in
+      reentrant way now.
+
+      TODO: We can circumvent this problem by using separate
+      sp_head instances for each recursive invocation.
+
+      NOTE: Theoretically arguments of procedure can be evaluated
+      before its invocation so there should be no problem with
+      recursion. But since we perform cleanup for CALL statement
+      as for any other statement only after its execution, its LEX
+      structure is not reusable for recursive calls. Thus we have
+      to prohibit recursion for stored procedures too.
+    */
+    my_error(ER_SP_NO_RECURSION, MYF(0));
+    DBUG_RETURN(-1);
+  }
+  m_is_invoked= TRUE;
+
   dbchanged= FALSE;
   if (m_db.length &&
       (ret= sp_use_new_db(thd, m_db.str, olddb, sizeof(olddb), 0, &dbchanged)))
@@ -704,6 +727,7 @@ sp_head::execute(THD *thd)
     if (! thd->killed)
       ret= sp_change_db(thd, olddb, 0);
   }
+  m_is_invoked= FALSE;
   DBUG_RETURN(ret);
 }
 

sql/sp_head.h

@@ -259,6 +259,9 @@ class sp_head :private Query_arena
   */
   HASH m_sptabs;
 
+  /* Used for tracking of routine invocations and preventing recursion. */
+  bool m_is_invoked;
+
   int
   execute(THD *thd);