Bug#26503 (Illegal SQL exception handler code causes the server to crash)

Before this fix, the parser would accept illegal code in SQL exceptions
handlers, that later causes the runtime to crash when executing the code,
due to memory violations in the exception handler stack.

The root cause of the problem is instructions within an exception handler
that jumps to code located outside of the handler. This is illegal according
to the SQL 2003 standard, since labels located outside the handler are not
supposed to be visible (they are "out of scope"), so any instruction that
jumps to these labels, like ITERATE or LEAVE, should not parse.

The section of the standard that is relevant for this is :
  SQL:2003 SQL/PSM (ISO/IEC 9075-4:2003)
  section 13.1 <compound statement>,
  syntax rule 4
<quote>
  The scope of the <beginning label> is CS excluding every <SQL schema
  statement> contained in CS and excluding every
  <local handler declaration list> contained in CS. <beginning label> shall
  not be equivalent to any other <beginning label>s within that scope.
</quote>

With this fix, the C++ class sp_pcontext, which represent the "parsing
context" tree (a.k.a symbol table) of a stored procedure, has been changed
as follows:
- constructors have been cleaned up, so that only building a root node for
the tree is public; building nodes inside a tree is not public.
- a new member, m_label_scope, indicates if a given syntactic context
belongs to a DECLARE HANDLER block,
- label resolution, in the method find_label(), has been changed to
implement the restriction of scope regarding labels used in a compound
statement.

The actions in the parser, when parsing the body of a SQL exception handler,
have been changed as follows:
- the implementation of an exception handler (DECLARE HANDLER) now creates
explicitly a new sp_pcontext, to isolate the code inside the handler from
the containing compound statement context.
- registering exception handlers as a result occurs in the parent context,
see the rule sp_hcond_element
- the code in sp_hcond_list has been cleaned up, to avoid code duplication

In addition, the flags IN_SIMPLE_CASE and IN_HANDLER, declared in sp_head.h
have been removed, since they are unused and broken by design (as seen with
Bug 19194 (Right recursion in parser for CASE causes excessive stack usage,
limitation), representing a stack in a single flag is not possible.

Tests in sp-error have been added to show that illegal constructs are now
rejected.

Tests in sp have been added for code coverage, to show that ITERATE or LEAVE
statements are legal when jumping to a label in scope, inside the body of
an exception handler.


mysql-test/r/sp-error.result:
  SQL Exception handlers define a parsing context for label resolution.
mysql-test/r/sp.result:
  SQL Exception handlers define a parsing context for label resolution.
mysql-test/t/sp-error.test:
  SQL Exception handlers define a parsing context for label resolution.
mysql-test/t/sp.test:
  SQL Exception handlers define a parsing context for label resolution.
sql/sp_head.cc:
  Minor cleanup
sql/sp_head.h:
  Minor cleanup
sql/sp_pcontext.cc:
  SQL Exception handlers define a parsing context for label resolution.
sql/sp_pcontext.h:
  SQL Exception handlers define a parsing context for label resolution.
sql/sql_yacc.yy:
  SQL Exception handlers define a parsing context for label resolution.

9 files changed, 556 insertions, 62 deletions

diff --git a/mysql-test/r/sp-error.result b/mysql-test/r/sp-error.result
index 332d4fa4519..bdcb51c4db8 100644
--- a/mysql-test/r/sp-error.result
+++ b/mysql-test/r/sp-error.result
@@ -1400,3 +1400,55 @@ drop table table_25345_b;
 drop procedure proc_25345;
 drop function func_25345;
 drop function func_25345_b;
+create procedure proc_26503_error_1()
+begin
+retry:
+repeat
+begin
+declare continue handler for sqlexception
+begin
+iterate retry;
+end
+select "do something";
+end
+until true end repeat retry;
+end//
+ERROR 42000: ITERATE with no matching label: retry
+create procedure proc_26503_error_2()
+begin
+retry:
+repeat
+begin
+declare continue handler for sqlexception
+iterate retry;
+select "do something";
+end
+until true end repeat retry;
+end//
+ERROR 42000: ITERATE with no matching label: retry
+create procedure proc_26503_error_3()
+begin
+retry:
+repeat
+begin
+declare continue handler for sqlexception
+begin
+leave retry;
+end
+select "do something";
+end
+until true end repeat retry;
+end//
+ERROR 42000: LEAVE with no matching label: retry
+create procedure proc_26503_error_4()
+begin
+retry:
+repeat
+begin
+declare continue handler for sqlexception
+leave retry;
+select "do something";
+end
+until true end repeat retry;
+end//
+ERROR 42000: LEAVE with no matching label: retry
diff --git a/mysql-test/r/sp.result b/mysql-test/r/sp.result
index afc3b95eb5f..fb8b7467746 100644
--- a/mysql-test/r/sp.result
+++ b/mysql-test/r/sp.result
@@ -5805,4 +5805,169 @@ func_8407_b()
 1500
 drop function func_8407_a|
 drop function func_8407_b|
+drop table if exists table_26503|
+drop procedure if exists proc_26503_ok_1|
+drop procedure if exists proc_26503_ok_2|
+drop procedure if exists proc_26503_ok_3|
+drop procedure if exists proc_26503_ok_4|
+create table table_26503(a int unique)|
+create procedure proc_26503_ok_1(v int)
+begin
+declare i int default 5;
+declare continue handler for sqlexception
+begin
+select 'caught something';
+retry:
+while i > 0 do
+begin
+set i = i - 1;
+select 'looping', i;
+iterate retry;
+select 'dead code';
+end;
+end while retry;
+select 'leaving handler';
+end;
+select 'do something';
+insert into table_26503 values (v);
+select 'do something again';
+insert into table_26503 values (v);
+end|
+create procedure proc_26503_ok_2(v int)
+begin
+declare i int default 5;
+declare continue handler for sqlexception
+begin
+select 'caught something';
+retry:
+while i > 0 do
+begin
+set i = i - 1;
+select 'looping', i;
+leave retry;
+select 'dead code';
+end;
+end while;
+select 'leaving handler';
+end;
+select 'do something';
+insert into table_26503 values (v);
+select 'do something again';
+insert into table_26503 values (v);
+end|
+create procedure proc_26503_ok_3(v int)
+begin
+declare i int default 5;
+retry:
+begin
+declare continue handler for sqlexception
+begin
+select 'caught something';
+retry:
+while i > 0 do
+begin
+set i = i - 1;
+select 'looping', i;
+iterate retry;
+select 'dead code';
+end;
+end while retry;
+select 'leaving handler';
+end;
+select 'do something';
+insert into table_26503 values (v);
+select 'do something again';
+insert into table_26503 values (v);
+end;
+end|
+create procedure proc_26503_ok_4(v int)
+begin
+declare i int default 5;
+retry:
+begin
+declare continue handler for sqlexception
+begin
+select 'caught something';
+retry:
+while i > 0 do
+begin
+set i = i - 1;
+select 'looping', i;
+leave retry;
+select 'dead code';
+end;
+end while;
+select 'leaving handler';
+end;
+select 'do something';
+insert into table_26503 values (v);
+select 'do something again';
+insert into table_26503 values (v);
+end;
+end|
+call proc_26503_ok_1(1)|
+do something
+do something
+do something again
+do something again
+caught something
+caught something
+looping	i
+looping	4
+looping	i
+looping	3
+looping	i
+looping	2
+looping	i
+looping	1
+looping	i
+looping	0
+leaving handler
+leaving handler
+call proc_26503_ok_2(2)|
+do something
+do something
+do something again
+do something again
+caught something
+caught something
+looping	i
+looping	4
+leaving handler
+leaving handler
+call proc_26503_ok_3(3)|
+do something
+do something
+do something again
+do something again
+caught something
+caught something
+looping	i
+looping	4
+looping	i
+looping	3
+looping	i
+looping	2
+looping	i
+looping	1
+looping	i
+looping	0
+leaving handler
+leaving handler
+call proc_26503_ok_4(4)|
+do something
+do something
+do something again
+do something again
+caught something
+caught something
+looping	i
+looping	4
+leaving handler
+leaving handler
+drop table table_26503|
+drop procedure proc_26503_ok_1|
+drop procedure proc_26503_ok_2|
+drop procedure proc_26503_ok_3|
+drop procedure proc_26503_ok_4|
 drop table t1,t2;
diff --git a/mysql-test/t/sp-error.test b/mysql-test/t/sp-error.test
index 396c1552e37..9e5c795d586 100644
--- a/mysql-test/t/sp-error.test
+++ b/mysql-test/t/sp-error.test
@@ -2022,6 +2022,74 @@ drop function func_25345;
 drop function func_25345_b;
 
 #
+# Bug#26503 (Illegal SQL exception handler code causes the server to crash)
+#
+
+delimiter //;
+
+--error ER_SP_LILABEL_MISMATCH
+create procedure proc_26503_error_1()
+begin
+retry:
+  repeat
+    begin
+      declare continue handler for sqlexception
+      begin
+        iterate retry;
+      end
+
+      select "do something";
+    end
+  until true end repeat retry;
+end//
+
+--error ER_SP_LILABEL_MISMATCH
+create procedure proc_26503_error_2()
+begin
+retry:
+  repeat
+    begin
+      declare continue handler for sqlexception
+        iterate retry;
+
+      select "do something";
+    end
+  until true end repeat retry;
+end//
+
+--error ER_SP_LILABEL_MISMATCH
+create procedure proc_26503_error_3()
+begin
+retry:
+  repeat
+    begin
+      declare continue handler for sqlexception
+      begin
+        leave retry;
+      end
+
+      select "do something";
+    end
+  until true end repeat retry;
+end//
+
+--error ER_SP_LILABEL_MISMATCH
+create procedure proc_26503_error_4()
+begin
+retry:
+  repeat
+    begin
+      declare continue handler for sqlexception
+        leave retry;
+
+      select "do something";
+    end
+  until true end repeat retry;
+end//
+
+delimiter ;//
+
+#
 # BUG#NNNN: New bug synopsis
 #
 #--disable_warnings
diff --git a/mysql-test/t/sp.test b/mysql-test/t/sp.test
index 80fb1354b16..48e266bfbf6 100644
--- a/mysql-test/t/sp.test
+++ b/mysql-test/t/sp.test
@@ -6801,6 +6801,141 @@ drop function func_8407_a|
 drop function func_8407_b|
 
 #
+# Bug#26503 (Illegal SQL exception handler code causes the server to crash)
+#
+
+--disable_warnings
+drop table if exists table_26503|
+drop procedure if exists proc_26503_ok_1|
+drop procedure if exists proc_26503_ok_2|
+drop procedure if exists proc_26503_ok_3|
+drop procedure if exists proc_26503_ok_4|
+--enable_warnings
+
+create table table_26503(a int unique)|
+
+create procedure proc_26503_ok_1(v int)
+begin
+  declare i int default 5;
+
+  declare continue handler for sqlexception
+  begin
+    select 'caught something';
+    retry:
+    while i > 0 do
+      begin
+        set i = i - 1;
+        select 'looping', i;
+        iterate retry;
+        select 'dead code';
+      end;
+    end while retry;
+    select 'leaving handler';
+  end;
+
+  select 'do something';
+  insert into table_26503 values (v);
+  select 'do something again';
+  insert into table_26503 values (v);
+end|
+
+create procedure proc_26503_ok_2(v int)
+begin
+  declare i int default 5;
+
+  declare continue handler for sqlexception
+  begin
+    select 'caught something';
+    retry:
+    while i > 0 do
+      begin
+        set i = i - 1;
+        select 'looping', i;
+        leave retry;
+        select 'dead code';
+      end;
+    end while;
+    select 'leaving handler';
+  end;
+
+  select 'do something';
+  insert into table_26503 values (v);
+  select 'do something again';
+  insert into table_26503 values (v);
+end|
+
+## The outer retry label should not prevent using the inner label.
+
+create procedure proc_26503_ok_3(v int)
+begin
+  declare i int default 5;
+
+retry:
+  begin
+    declare continue handler for sqlexception
+    begin
+      select 'caught something';
+      retry:
+      while i > 0 do
+        begin
+          set i = i - 1;
+          select 'looping', i;
+          iterate retry;
+          select 'dead code';
+        end;
+      end while retry;
+      select 'leaving handler';
+    end;
+
+    select 'do something';
+    insert into table_26503 values (v);
+    select 'do something again';
+    insert into table_26503 values (v);
+  end;
+end|
+
+## The outer retry label should not prevent using the inner label.
+
+create procedure proc_26503_ok_4(v int)
+begin
+  declare i int default 5;
+
+retry:
+  begin
+    declare continue handler for sqlexception
+    begin
+      select 'caught something';
+      retry:
+      while i > 0 do
+        begin
+          set i = i - 1;
+          select 'looping', i;
+          leave retry;
+          select 'dead code';
+        end;
+      end while;
+      select 'leaving handler';
+    end;
+
+    select 'do something';
+    insert into table_26503 values (v);
+    select 'do something again';
+    insert into table_26503 values (v);
+  end;
+end|
+
+call proc_26503_ok_1(1)|
+call proc_26503_ok_2(2)|
+call proc_26503_ok_3(3)|
+call proc_26503_ok_4(4)|
+
+drop table table_26503|
+drop procedure proc_26503_ok_1|
+drop procedure proc_26503_ok_2|
+drop procedure proc_26503_ok_3|
+drop procedure proc_26503_ok_4|
+
+#
 # NOTE: The delimiter is `|`, and not `;`. It is changed to `;`
 #       at the end of the file!
 #
diff --git a/sql/sp_head.cc b/sql/sp_head.cc
index c1643f0f82e..63ee37e1135 100644
--- a/sql/sp_head.cc
+++ b/sql/sp_head.cc
@@ -470,7 +470,7 @@ sp_head::init(LEX *lex)
 {
   DBUG_ENTER("sp_head::init");
 
-  lex->spcont= m_pcont= new sp_pcontext(NULL);
+  lex->spcont= m_pcont= new sp_pcontext();
 
   /*
     Altough trg_table_fields list is used only in triggers we init for all
diff --git a/sql/sp_head.h b/sql/sp_head.h
index 4ef4077cc79..901b7a19c39 100644
--- a/sql/sp_head.h
+++ b/sql/sp_head.h
@@ -107,8 +107,6 @@ public:
   /* Possible values of m_flags */
   enum {
     HAS_RETURN= 1,              // For FUNCTIONs only: is set if has RETURN
-    IN_SIMPLE_CASE= 2,          // Is set if parsing a simple CASE
-    IN_HANDLER= 4,              // Is set if the parser is in a handler body
     MULTI_RESULTS= 8,           // Is set if a procedure with SELECT(s)
     CONTAINS_DYNAMIC_SQL= 16,   // Is set if a procedure with PREPARE/EXECUTE
     IS_INVOKED= 32,             // Is set if this sp_head is being used
diff --git a/sql/sp_pcontext.cc b/sql/sp_pcontext.cc
index 6229cf14604..780243cc79f 100644
--- a/sql/sp_pcontext.cc
+++ b/sql/sp_pcontext.cc
@@ -25,6 +25,11 @@
 #include "sp_pcontext.h"
 #include "sp_head.h"
 
+/* Initial size for the dynamic arrays in sp_pcontext */
+#define PCONTEXT_ARRAY_INIT_ALLOC 16
+/* Increment size for the dynamic arrays in sp_pcontext */
+#define PCONTEXT_ARRAY_INCREMENT_ALLOC 8
+
 /*
   Sanity check for SQLSTATEs. Will not check if it's really an existing
   state (there are just too many), but will check length and bad characters.
@@ -49,28 +54,61 @@ sp_cond_check(LEX_STRING *sqlstate)
   return TRUE;
 }
 
-sp_pcontext::sp_pcontext(sp_pcontext *prev)
-  :Sql_alloc(), m_max_var_index(0), m_max_cursor_index(0), m_max_handler_index(0),
-   m_context_handlers(0), m_parent(prev), m_pboundary(0)
+sp_pcontext::sp_pcontext()
+  : Sql_alloc(),
+  m_max_var_index(0), m_max_cursor_index(0), m_max_handler_index(0),
+  m_context_handlers(0), m_parent(NULL), m_pboundary(0),
+  m_label_scope(LABEL_DEFAULT_SCOPE)
 {
-  VOID(my_init_dynamic_array(&m_vars, sizeof(sp_variable_t *), 16, 8));
-  VOID(my_init_dynamic_array(&m_case_expr_id_lst, sizeof(int), 16, 8));
-  VOID(my_init_dynamic_array(&m_conds, sizeof(sp_cond_type_t *), 16, 8));
-  VOID(my_init_dynamic_array(&m_cursors, sizeof(LEX_STRING), 16, 8));
-  VOID(my_init_dynamic_array(&m_handlers, sizeof(sp_cond_type_t *), 16, 8));
+  VOID(my_init_dynamic_array(&m_vars, sizeof(sp_variable_t *),
+                             PCONTEXT_ARRAY_INIT_ALLOC,
+                             PCONTEXT_ARRAY_INCREMENT_ALLOC));
+  VOID(my_init_dynamic_array(&m_case_expr_id_lst, sizeof(int),
+                             PCONTEXT_ARRAY_INIT_ALLOC,
+                             PCONTEXT_ARRAY_INCREMENT_ALLOC));
+  VOID(my_init_dynamic_array(&m_conds, sizeof(sp_cond_type_t *),
+                             PCONTEXT_ARRAY_INIT_ALLOC,
+                             PCONTEXT_ARRAY_INCREMENT_ALLOC));
+  VOID(my_init_dynamic_array(&m_cursors, sizeof(LEX_STRING),
+                             PCONTEXT_ARRAY_INIT_ALLOC,
+                             PCONTEXT_ARRAY_INCREMENT_ALLOC));
+  VOID(my_init_dynamic_array(&m_handlers, sizeof(sp_cond_type_t *),
+                             PCONTEXT_ARRAY_INIT_ALLOC,
+                             PCONTEXT_ARRAY_INCREMENT_ALLOC));
   m_label.empty();
   m_children.empty();
-  if (!prev)
-  {
-    m_var_offset= m_cursor_offset= 0;
-    m_num_case_exprs= 0;
-  }
-  else
-  {
-    m_var_offset= prev->m_var_offset + prev->m_max_var_index;
-    m_cursor_offset= prev->current_cursor_count();
-    m_num_case_exprs= prev->get_num_case_exprs();
-  }
+
+  m_var_offset= m_cursor_offset= 0;
+  m_num_case_exprs= 0;
+}
+
+sp_pcontext::sp_pcontext(sp_pcontext *prev, label_scope_type label_scope)
+  : Sql_alloc(),
+  m_max_var_index(0), m_max_cursor_index(0), m_max_handler_index(0),
+  m_context_handlers(0), m_parent(prev), m_pboundary(0),
+  m_label_scope(label_scope)
+{
+  VOID(my_init_dynamic_array(&m_vars, sizeof(sp_variable_t *),
+                             PCONTEXT_ARRAY_INIT_ALLOC,
+                             PCONTEXT_ARRAY_INCREMENT_ALLOC));
+  VOID(my_init_dynamic_array(&m_case_expr_id_lst, sizeof(int),
+                             PCONTEXT_ARRAY_INIT_ALLOC,
+                             PCONTEXT_ARRAY_INCREMENT_ALLOC));
+  VOID(my_init_dynamic_array(&m_conds, sizeof(sp_cond_type_t *),
+                             PCONTEXT_ARRAY_INIT_ALLOC,
+                             PCONTEXT_ARRAY_INCREMENT_ALLOC));
+  VOID(my_init_dynamic_array(&m_cursors, sizeof(LEX_STRING),
+                             PCONTEXT_ARRAY_INIT_ALLOC,
+                             PCONTEXT_ARRAY_INCREMENT_ALLOC));
+  VOID(my_init_dynamic_array(&m_handlers, sizeof(sp_cond_type_t *),
+                             PCONTEXT_ARRAY_INIT_ALLOC,
+                             PCONTEXT_ARRAY_INCREMENT_ALLOC));
+  m_label.empty();
+  m_children.empty();
+
+  m_var_offset= prev->m_var_offset + prev->m_max_var_index;
+  m_cursor_offset= prev->current_cursor_count();
+  m_num_case_exprs= prev->get_num_case_exprs();
 }
 
 void
@@ -92,9 +130,9 @@ sp_pcontext::destroy()
 }
 
 sp_pcontext *
-sp_pcontext::push_context()
+sp_pcontext::push_context(label_scope_type label_scope)
 {
-  sp_pcontext *child= new sp_pcontext(this);
+  sp_pcontext *child= new sp_pcontext(this, label_scope);
 
   if (child)
     m_children.push_back(child);
@@ -257,7 +295,15 @@ sp_pcontext::find_label(char *name)
     if (my_strcasecmp(system_charset_info, name, lab->name) == 0)
       return lab;
 
-  if (m_parent)
+  /*
+    Note about exception handlers.
+    See SQL:2003 SQL/PSM (ISO/IEC 9075-4:2003),
+    section 13.1 <compound statement>,
+    syntax rule 4.
+    In short, a DECLARE HANDLER block can not refer
+    to labels from the parent context, as they are out of scope.
+  */
+  if (m_parent && (m_label_scope == LABEL_DEFAULT_SCOPE))
     return m_parent->find_label(name);
   return NULL;
 }
diff --git a/sql/sp_pcontext.h b/sql/sp_pcontext.h
index b2cdd5e689c..5bffda79f98 100644
--- a/sql/sp_pcontext.h
+++ b/sql/sp_pcontext.h
@@ -88,16 +88,33 @@ typedef struct sp_cond
   sp_cond_type_t *val;
 } sp_cond_t;
 
+/**
+  The scope of a label in Stored Procedures,
+  for name resolution of labels in a parsing context.
+*/
+enum label_scope_type
+{
+  /**
+    The labels declared in a parent context are in scope.
+  */
+  LABEL_DEFAULT_SCOPE,
+  /**
+    The labels declared in a parent context are not in scope.
+  */
+  LABEL_HANDLER_SCOPE
+};
 
-/*
-  The parse-time context, used to keep track on declared variables/parameters,
+/**
+  The parse-time context, used to keep track of declared variables/parameters,
   conditions, handlers, cursors and labels, during parsing.
   sp_contexts are organized as a tree, with one object for each begin-end
-  block, plus a root-context for the parameters.
+  block, one object for each exception handler,
+  plus a root-context for the parameters.
   This is used during parsing for looking up defined names (e.g. declared
   variables and visible labels), for error checking, and to calculate offsets
   to be used at runtime. (During execution variable values, active handlers
   and cursors, etc, are referred to by an index in a stack.)
+  Parsing contexts for exception handlers limit the visibility of labels.
   The pcontext tree is also kept during execution and is used for error
   checking (e.g. correct number of parameters), and in the future, used by
   the debugger.
@@ -105,21 +122,30 @@ typedef struct sp_cond
 
 class sp_pcontext : public Sql_alloc
 {
-  sp_pcontext(const sp_pcontext &); /* Prevent use of these */
-  void operator=(sp_pcontext &);
+public:
 
- public:
-
-  sp_pcontext(sp_pcontext *prev);
+  /**
+    Constructor.
+    Builds a parsing context root node.
+  */
+  sp_pcontext();
 
   // Free memory
   void
   destroy();
 
+  /**
+    Create and push a new context in the tree.
+    @param label_scope label scope for the new parsing context
+    @return the node created
+  */
   sp_pcontext *
-  push_context();
+  push_context(label_scope_type label_scope);
 
-  // Returns the previous context, not the one we pop
+  /**
+    Pop a node from the parsing context tree.
+    @return the parent node
+  */
   sp_pcontext *
   pop_context();
 
@@ -363,6 +389,13 @@ class sp_pcontext : public Sql_alloc
 
 protected:
 
+  /**
+    Constructor for a tree node.
+    @param prev the parent parsing context
+    @param label_scope label_scope for this parsing context
+  */
+  sp_pcontext(sp_pcontext *prev, label_scope_type label_scope);
+
   /*
     m_max_var_index -- number of variables (including all types of arguments)
     in this context including all children contexts.
@@ -416,6 +449,14 @@ private:
 
   List<sp_pcontext> m_children;	// Children contexts, used for destruction
 
+  /**
+    Scope of labels for this parsing context.
+  */
+  label_scope_type m_label_scope;
+
+private:
+  sp_pcontext(const sp_pcontext &); /* Prevent use of these */
+  void operator=(sp_pcontext &);
 }; // class sp_pcontext : public Sql_alloc
 
 
diff --git a/sql/sql_yacc.yy b/sql/sql_yacc.yy
index d07234ff2bd..812482e8ffb 100644
--- a/sql/sql_yacc.yy
+++ b/sql/sql_yacc.yy
@@ -2006,6 +2006,9 @@ sp_decl:
 	  {
 	    LEX *lex= Lex;
 	    sp_head *sp= lex->sphead;
+
+            lex->spcont= lex->spcont->push_context(LABEL_HANDLER_SCOPE);
+
 	    sp_pcontext *ctx= lex->spcont;
 	    sp_instr_hpush_jump *i=
               new sp_instr_hpush_jump(sp->instructions(), ctx, $2,
@@ -2013,7 +2016,6 @@ sp_decl:
 
 	    sp->add_instr(i);
 	    sp->push_backpatch(i, ctx->push_label((char *)"", 0));
-	    sp->m_flags|= sp_head::IN_HANDLER;
 	  }
 	  sp_hcond_list sp_proc_stmt
 	  {
@@ -2037,10 +2039,12 @@ sp_decl:
 	      sp->push_backpatch(i, lex->spcont->last_label()); /* Block end */
 	    }
 	    lex->sphead->backpatch(hlab);
-	    sp->m_flags&= ~sp_head::IN_HANDLER;
+
+            lex->spcont= ctx->pop_context();
+
 	    $$.vars= $$.conds= $$.curs= 0;
 	    $$.hndlrs= $6;
-	    ctx->add_handlers($6);
+	    lex->spcont->add_handlers($6);
 	  }
 	| DECLARE_SYM ident CURSOR_SYM FOR_SYM sp_cursor_stmt
 	  {
@@ -2103,11 +2107,18 @@ sp_handler_type:
 	;
 
 sp_hcond_list:
+          sp_hcond_element
+          { $$= 1; }
+        | sp_hcond_list ',' sp_hcond_element
+          { $$+= 1; }
+        ;
+
+sp_hcond_element:
 	  sp_hcond
 	  {
 	    LEX *lex= Lex;
 	    sp_head *sp= lex->sphead;
-	    sp_pcontext *ctx= lex->spcont;
+	    sp_pcontext *ctx= lex->spcont->parent_context();
 
 	    if (ctx->find_handler($1))
 	    {
@@ -2121,28 +2132,6 @@ sp_hcond_list:
 
 	      i->add_condition($1);
 	      ctx->push_handler($1);
-	      $$= 1;
-	    }
-	  }
-	| sp_hcond_list ',' sp_hcond
-	  {
-	    LEX *lex= Lex;
-	    sp_head *sp= lex->sphead;
-	    sp_pcontext *ctx= lex->spcont;
-
-	    if (ctx->find_handler($3))
-	    {
-	      my_message(ER_SP_DUP_HANDLER, ER(ER_SP_DUP_HANDLER), MYF(0));
-	      MYSQL_YYABORT;
-	    }
-	    else
-	    {
-	      sp_instr_hpush_jump *i=
-	        (sp_instr_hpush_jump *)sp->last_instruction();
-
-	      i->add_condition($3);
-	      ctx->push_handler($3);
-	      $$= $1 + 1;
 	    }
 	  }
 	;
@@ -2687,7 +2676,7 @@ sp_unlabeled_control:
 	    sp_label_t *lab= lex->spcont->last_label();
 
 	    lab->type= SP_LAB_BEGIN;
-	    lex->spcont= lex->spcont->push_context();
+	    lex->spcont= lex->spcont->push_context(LABEL_DEFAULT_SCOPE);
 	  }
 	  sp_decls
 	  sp_proc_stmts