Bug#35577 (CREATE PROCEDURE causes either crash or syntax error depending on

build)

The crash was caused by freeing the internal parser stack during the parser
execution.
This occured only for complex stored procedures, after reallocating the parser
stack using my_yyoverflow(), with the following C call stack:
- MYSQLparse()
- any rule calling sp_head::restore_lex()
- lex_end()
- x_free(lex->yacc_yyss), xfree(lex->yacc_yyvs)

The root cause is the implementation of stored procedures, which breaks the
assumption from 4.1 that there is only one LEX structure per parser call.

The solution is to separate the LEX structure into:
- attributes that represent a statement (the current LEX structure),
- attributes that relate to the syntax parser itself (Yacc_state),
so that parsing multiple statements in stored programs can create multiple
LEX structures while not changing the unique Yacc_state.

Now, Yacc_state and the existing Lex_input_stream are aggregated into
Parser_state, a structure that represent the complete state of the (Lexical +
Syntax) parser.


mysql-test/r/parser_stack.result:
  Bug#35577 (CREATE PROCEDURE causes either crash or syntax error depending on
  build)
mysql-test/t/parser_stack.test:
  Bug#35577 (CREATE PROCEDURE causes either crash or syntax error depending on
  build)
sql/sp.cc:
  Bug#35577 (CREATE PROCEDURE causes either crash or syntax error depending on
  build)
sql/sp_head.cc:
  Bug#35577 (CREATE PROCEDURE causes either crash or syntax error depending on
  build)
sql/sql_class.cc:
  Bug#35577 (CREATE PROCEDURE causes either crash or syntax error depending on
  build)
sql/sql_class.h:
  Bug#35577 (CREATE PROCEDURE causes either crash or syntax error depending on
  build)
sql/sql_lex.cc:
  Bug#35577 (CREATE PROCEDURE causes either crash or syntax error depending on
  build)
sql/sql_lex.h:
  Bug#35577 (CREATE PROCEDURE causes either crash or syntax error depending on
  build)
sql/sql_parse.cc:
  Bug#35577 (CREATE PROCEDURE causes either crash or syntax error depending on
  build)
sql/sql_prepare.cc:
  Bug#35577 (CREATE PROCEDURE causes either crash or syntax error depending on
  build)
sql/sql_trigger.cc:
  Bug#35577 (CREATE PROCEDURE causes either crash or syntax error depending on
  build)
sql/sql_view.cc:
  Bug#35577 (CREATE PROCEDURE causes either crash or syntax error depending on
  build)
sql/sql_yacc.yy:
  Bug#35577 (CREATE PROCEDURE causes either crash or syntax error depending on
  build)

mysql-test/r/parser_stack.result

+use test;
+SELECT
+((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((
+((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((
+((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((
+1
+))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))
+))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))
+))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))
+;
+1
+1
+prepare stmt from
+"
+SELECT
+((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((
+((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((
+((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((
+1
+))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))
+))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))
+))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))
+"
+;
+execute stmt;
+1
+1
+drop view if exists view_overflow;
+CREATE VIEW view_overflow AS
+SELECT
+((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((
+((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((
+((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((
+1
+))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))
+))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))
+))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))
+;
+SELECT * from view_overflow;
+1
+1
+drop view view_overflow;
+drop procedure if exists proc_overflow;
+CREATE PROCEDURE proc_overflow()
+BEGIN
+BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN
+BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN
+BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN
+BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN
+BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN
+BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN
+BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN
+BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN
+BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN
+BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN
+select 1;
+select 2;
+select 3;
+END;  END;  END;  END;  END;  END;  END;  END;  END;  END;  END;  END;
+END;  END;  END;  END;  END;  END;  END;  END;  END;  END;  END;  END;
+END;  END;  END;  END;  END;  END;  END;  END;  END;  END;  END;  END;
+END;  END;  END;  END;  END;  END;  END;  END;  END;  END;  END;  END;
+END;  END;  END;  END;  END;  END;  END;  END;  END;  END;  END;  END;
+END;  END;  END;  END;  END;  END;  END;  END;  END;  END;  END;  END;
+END;  END;  END;  END;  END;  END;  END;  END;  END;  END;  END;  END;
+END;  END;  END;  END;  END;  END;  END;  END;  END;  END;  END;  END;
+END;  END;  END;  END;  END;  END;  END;  END;  END;  END;  END;  END;
+END;  END;  END;  END;  END;  END;  END;  END;  END;  END;  END;  END;
+END $$
+call proc_overflow();
+1
+1
+2
+2
+3
+3
+drop procedure proc_overflow;
+drop function if exists func_overflow;
+create function func_overflow() returns int
+BEGIN
+DECLARE x int default 0;
+BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN
+BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN
+BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN
+BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN
+BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN
+BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN
+BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN
+BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN
+BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN
+BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN
+SET x=x+1;
+SET x=x+2;
+SET x=x+3;
+END;  END;  END;  END;  END;  END;  END;  END;  END;  END;  END;  END;
+END;  END;  END;  END;  END;  END;  END;  END;  END;  END;  END;  END;
+END;  END;  END;  END;  END;  END;  END;  END;  END;  END;  END;  END;
+END;  END;  END;  END;  END;  END;  END;  END;  END;  END;  END;  END;
+END;  END;  END;  END;  END;  END;  END;  END;  END;  END;  END;  END;
+END;  END;  END;  END;  END;  END;  END;  END;  END;  END;  END;  END;
+END;  END;  END;  END;  END;  END;  END;  END;  END;  END;  END;  END;
+END;  END;  END;  END;  END;  END;  END;  END;  END;  END;  END;  END;
+END;  END;  END;  END;  END;  END;  END;  END;  END;  END;  END;  END;
+END;  END;  END;  END;  END;  END;  END;  END;  END;  END;  END;  END;
+return x;
+END $$
+select func_overflow();
+func_overflow()
+6
+drop function func_overflow;
+drop table if exists table_overflow;
+create table table_overflow(a int, b int);
+create trigger trigger_overflow before insert on table_overflow
+for each row
+BEGIN
+BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN
+BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN
+BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN
+BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN
+BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN
+BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN
+BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN
+BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN
+BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN
+BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN BEGIN
+SET NEW.b := NEW.a;
+SET NEW.b := NEW.b + 1;
+SET NEW.b := NEW.b + 2;
+SET NEW.b := NEW.b + 3;
+END;  END;  END;  END;  END;  END;  END;  END;  END;  END;  END;  END;
+END;  END;  END;  END;  END;  END;  END;  END;  END;  END;  END;  END;
+END;  END;  END;  END;  END;  END;  END;  END;  END;  END;  END;  END;
+END;  END;  END;  END;  END;  END;  END;  END;  END;  END;  END;  END;
+END;  END;  END;  END;  END;  END;  END;  END;  END;  END;  END;  END;
+END;  END;  END;  END;  END;  END;  END;  END;  END;  END;  END;  END;
+END;  END;  END;  END;  END;  END;  END;  END;  END;  END;  END;  END;
+END;  END;  END;  END;  END;  END;  END;  END;  END;  END;  END;  END;
+END;  END;  END;  END;  END;  END;  END;  END;  END;  END;  END;  END;
+END;  END;  END;  END;  END;  END;  END;  END;  END;  END;  END;  END;
+END $$
+insert into table_overflow set a=10;
+insert into table_overflow set a=20;
+select * from table_overflow;
+a	b
+10	16
+20	26
+drop table table_overflow;
+drop procedure if exists proc_35577;
+CREATE PROCEDURE proc_35577()
+BEGIN
+DECLARE z_done INT DEFAULT 0;
+DECLARE t_done VARCHAR(5000);
+outer_loop: LOOP
+IF t_done=1  THEN
+LEAVE outer_loop;
+END IF;
+inner_block:BEGIN
+DECLARE z_done INT DEFAULT  0;
+SET z_done = 0;
+inner_loop: LOOP
+IF z_done=1  THEN
+LEAVE inner_loop;
+END IF;
+IF (t_done = 'a') THEN
+IF (t_done <> 0) THEN
+IF ( t_done > 0) THEN
+IF (t_done = 'a') THEN
+SET t_done = 'a';
+ELSEIF (t_done = 'a') THEN
+SET t_done = 'a';
+ELSEIF(t_done = 'a') THEN
+SET t_done = 'a';
+ELSEIF(t_done = 'a') THEN
+SET t_done = 'a';
+ELSEIF(t_done = 'a') THEN
+SET t_done = 'a';
+ELSEIF(t_done = 'a') THEN
+SET t_done = 'a';
+ELSEIF(t_done = 'a') THEN
+SET t_done = 'a';
+ELSEIF(t_done = 'a') THEN
+SET t_done = 'a';
+END IF;
+END IF;
+END IF;
+END IF;
+END LOOP inner_loop;
+END inner_block;
+END LOOP outer_loop;
+END $$
+drop procedure proc_35577;
+drop procedure if exists p_37269;
+create procedure p_37269()
+begin
+declare done int default 0;
+declare varb int default 0;
+declare vara int default 0;
+repeat
+select now();
+until done end repeat;
+while varb do
+select now();
+begin
+select now();
+repeat
+select now();
+until done end repeat;
+if vara then 
+select now();
+repeat
+select now();
+loop
+select now();
+end loop;
+repeat
+select now();
+label1: while varb do
+select now();
+end while label1;
+if vara then 
+select now();
+repeat
+select now();
+until done end repeat;
+begin
+select now();
+while varb do
+select now();
+label1: while varb do
+select now();
+end while label1;
+if vara then 
+select now();
+while varb do
+select now();
+loop
+select now();
+end loop;
+repeat
+select now();
+loop
+select now();
+while varb do
+select now();
+end while;
+repeat
+select now();
+label1: loop
+select now();
+if vara then 
+select now();
+end if;
+end loop label1;
+until done end repeat;
+end loop;
+until done end repeat;
+end while;
+end if;
+end while;
+end;
+end if;
+until done end repeat;
+until done end repeat;
+end if;
+end;
+end while;
+end $$
+drop procedure p_37269;
+drop procedure if exists p_37228;
+create procedure p_37228 ()
+BEGIN
+DECLARE v INT DEFAULT 123;
+IF (v > 1) THEN SET v = 1; 
+ELSEIF (v < 10) THEN SET v = 10;
+ELSEIF (v < 11) THEN SET v = 11;
+ELSEIF (v < 12) THEN SET v = 12;
+ELSEIF (v < 13) THEN SET v = 13;
+ELSEIF (v < 14) THEN SET v = 14;
+ELSEIF (v < 15) THEN SET v = 15;
+ELSEIF (v < 16) THEN SET v = 16;
+ELSEIF (v < 17) THEN SET v = 17;
+ELSEIF (v < 18) THEN SET v = 18;
+ELSEIF (v < 19) THEN SET v = 19;
+ELSEIF (v < 20) THEN SET v = 20;
+ELSEIF (v < 21) THEN SET v = 21;
+ELSEIF (v < 22) THEN SET v = 22;
+ELSEIF (v < 23) THEN SET v = 23;
+ELSEIF (v < 24) THEN SET v = 24;
+ELSEIF (v < 25) THEN SET v = 25;
+ELSEIF (v < 26) THEN SET v = 26;
+ELSEIF (v < 27) THEN SET v = 27;
+ELSEIF (v < 28) THEN SET v = 28;
+ELSEIF (v < 29) THEN SET v = 29;
+ELSEIF (v < 30) THEN SET v = 30;
+ELSEIF (v < 31) THEN SET v = 31;
+ELSEIF (v < 32) THEN SET v = 32;
+ELSEIF (v < 33) THEN SET v = 33;
+ELSEIF (v < 34) THEN SET v = 34;
+ELSEIF (v < 35) THEN SET v = 35;
+ELSEIF (v < 36) THEN SET v = 36;
+ELSEIF (v < 37) THEN SET v = 37;
+ELSEIF (v < 38) THEN SET v = 38;
+ELSEIF (v < 39) THEN SET v = 39;
+END IF;
+END $$
+drop procedure p_37228;

sql/sp.cc

@@ -443,11 +443,12 @@ db_load_routine(THD *thd, int type, sp_name *name, sp_head **sphp,
     goto end;
 
   {
-    Lex_input_stream lip(thd, defstr.c_ptr(), defstr.length());
-    thd->m_lip= &lip;
+    Parser_state parser_state(thd, defstr.c_ptr(), defstr.length());
+    thd->m_parser_state= &parser_state;
     lex_start(thd);
     thd->spcont= NULL;
     ret= MYSQLparse(thd);
+    thd->m_parser_state= NULL;
 
     if (ret == 0)
     {

sql/sp_head.cc

@@ -591,7 +591,7 @@ sp_head::init_strings(THD *thd, LEX *lex)
   const char *endp;                  /* Used to trim the end */
   /* During parsing, we must use thd->mem_root */
   MEM_ROOT *root= thd->mem_root;
-  Lex_input_stream *lip=thd->m_lip;
+  Lex_input_stream *lip= & thd->m_parser_state->m_lip;
 
   if (m_param_begin && m_param_end)
   {

sql/sql_class.cc

@@ -177,7 +177,8 @@ THD::THD()
    rand_used(0), time_zone_used(0),
    last_insert_id_used(0), last_insert_id_used_bin_log(0), insert_id_used(0),
    clear_next_insert_id(0), in_lock_tables(0), bootstrap(0),
-   derived_tables_processing(FALSE), spcont(NULL), m_lip(NULL)
+   derived_tables_processing(FALSE), spcont(NULL),
+   m_parser_state(NULL)
 {
   ulong tmp;
 

sql/sql_class.h

@@ -28,7 +28,7 @@ class Slave_log_event;
 class Format_description_log_event;
 class sp_rcontext;
 class sp_cache;
-class Lex_input_stream;
+class Parser_state;
 
 enum enum_enable_or_disable { LEAVE_AS_IS, ENABLE, DISABLE };
 enum enum_ha_read_modes { RFIRST, RNEXT, RPREV, RLAST, RKEY, RNEXT_SAME };
@@ -1575,13 +1575,11 @@ class THD :public Statement,
   } binlog_evt_union;
 
   /**
-    Character input stream consumed by the lexical analyser,
-    used during parsing.
-    Note that since the parser is not re-entrant, we keep only one input
-    stream here. This member is valid only when executing code during parsing,
-    and may point to invalid memory after that.
+    Internal parser state.
+    Note that since the parser is not re-entrant, we keep only one parser
+    state here. This member is valid only when executing code during parsing.
   */
-  Lex_input_stream *m_lip;
+  Parser_state *m_parser_state;
 
   THD();
   ~THD();

sql/sql_lex.cc

@@ -192,7 +192,6 @@ void lex_start(THD *thd)
   lex->select_lex.order_list.empty();
   lex->select_lex.udf_list.empty();
   lex->current_select= &lex->select_lex;
-  lex->yacc_yyss=lex->yacc_yyvs=0;
   lex->sql_command= lex->orig_sql_command= SQLCOM_END;
   lex->duplicates= DUP_ERROR;
   lex->ignore= 0;
@@ -210,11 +209,16 @@ void lex_start(THD *thd)
 
 void lex_end(LEX *lex)
 {
-  DBUG_ENTER("lex_end");
-  DBUG_PRINT("enter", ("lex: 0x%lx", (long) lex));
-  x_free(lex->yacc_yyss);
-  x_free(lex->yacc_yyvs);
-  DBUG_VOID_RETURN;
+  /* Empty in 5.0, non empty in 5.1 */
+}
+
+Yacc_state::~Yacc_state()
+{
+  if (yacc_yyss)
+  {
+    x_free(yacc_yyss);
+    x_free(yacc_yyvs);
+  }
 }
 
 
@@ -531,7 +535,7 @@ int MYSQLlex(void *arg, void *yythd)
   uint length;
   enum my_lex_states state;
   THD *thd= (THD *)yythd;
-  Lex_input_stream *lip= thd->m_lip;
+  Lex_input_stream *lip= & thd->m_parser_state->m_lip;
   LEX *lex= thd->lex;
   YYSTYPE *yylval=(YYSTYPE*) arg;
   CHARSET_INFO *cs= thd->charset();
@@ -1781,7 +1785,7 @@ void Query_tables_list::destroy_query_tables_list()
 */
 
 st_lex::st_lex()
-  :result(0), yacc_yyss(0), yacc_yyvs(0),
+  :result(0),
    sql_command(SQLCOM_END)
 {
   reset_query_tables_list(TRUE);

sql/sql_lex.h

@@ -1004,7 +1004,6 @@ typedef struct st_lex : public Query_tables_list
   LEX_STRING comment, ident;
   LEX_USER *grant_user;
   XID *xid;
-  gptr yacc_yyss,yacc_yyvs;
   THD *thd;
   CHARSET_INFO *charset, *underscore_charset;
   bool text_string_is_7bit;
@@ -1290,6 +1289,59 @@ typedef struct st_lex : public Query_tables_list
   }
 } LEX;
 
+
+/**
+  The internal state of the syntax parser.
+  This object is only available during parsing,
+  and is private to the syntax parser implementation (sql_yacc.yy).
+*/
+class Yacc_state
+{
+public:
+  Yacc_state()
+    : yacc_yyss(NULL), yacc_yyvs(NULL)
+  {}
+
+  ~Yacc_state();
+
+  /**
+    Bison internal state stack, yyss, when dynamically allocated using
+    my_yyoverflow().
+  */
+  gptr yacc_yyss;
+
+  /**
+    Bison internal semantic value stack, yyvs, when dynamically allocated using
+    my_yyoverflow().
+  */
+  gptr yacc_yyvs;
+
+  /*
+    TODO: move more attributes from the LEX structure here.
+  */
+};
+
+/**
+  Internal state of the parser.
+  The complete state consist of:
+  - state data used during lexical parsing,
+  - state data used during syntactic parsing.
+*/
+class Parser_state
+{
+public:
+  Parser_state(THD *thd, const char* buff, unsigned int length)
+    : m_lip(thd, buff, length), m_yacc()
+  {}
+
+  ~Parser_state()
+  {}
+
+  Lex_input_stream m_lip;
+  Yacc_state m_yacc;
+};
+
+
 struct st_lex_local: public st_lex
 {
   static void *operator new(size_t size) throw()

sql/sql_parse.cc

@@ -5875,29 +5875,35 @@ bool check_stack_overrun(THD *thd, long margin,
 
 bool my_yyoverflow(short **yyss, YYSTYPE **yyvs, ulong *yystacksize)
 {
-  LEX	*lex= current_thd->lex;
+  Yacc_state *state= & current_thd->m_parser_state->m_yacc;
   ulong old_info=0;
+  DBUG_ASSERT(state);
   if ((uint) *yystacksize >= MY_YACC_MAX)
     return 1;
-  if (!lex->yacc_yyvs)
+  if (!state->yacc_yyvs)
     old_info= *yystacksize;
   *yystacksize= set_zone((*yystacksize)*2,MY_YACC_INIT,MY_YACC_MAX);
-  if (!(lex->yacc_yyvs= (char*)
-	my_realloc((gptr) lex->yacc_yyvs,
+  if (!(state->yacc_yyvs= (char*)
+        my_realloc(state->yacc_yyvs,
 		   *yystacksize*sizeof(**yyvs),
 		   MYF(MY_ALLOW_ZERO_PTR | MY_FREE_ON_ERROR))) ||
-      !(lex->yacc_yyss= (char*)
-	my_realloc((gptr) lex->yacc_yyss,
+      !(state->yacc_yyss= (char*)
+        my_realloc(state->yacc_yyss,
 		   *yystacksize*sizeof(**yyss),
 		   MYF(MY_ALLOW_ZERO_PTR | MY_FREE_ON_ERROR))))
     return 1;
   if (old_info)
-  {						// Copy old info from stack
-    memcpy(lex->yacc_yyss, (gptr) *yyss, old_info*sizeof(**yyss));
-    memcpy(lex->yacc_yyvs, (gptr) *yyvs, old_info*sizeof(**yyvs));
+  {
+    /*
+      Only copy the old stack on the first call to my_yyoverflow(),
+      when replacing a static stack (YYINITDEPTH) by a dynamic stack.
+      For subsequent calls, my_realloc already did preserve the old stack.
+    */
+    memcpy(state->yacc_yyss, *yyss, old_info*sizeof(**yyss));
+    memcpy(state->yacc_yyvs, *yyvs, old_info*sizeof(**yyvs));
   }
-  *yyss=(short*) lex->yacc_yyss;
-  *yyvs=(YYSTYPE*) lex->yacc_yyvs;
+  *yyss= (short*) state->yacc_yyss;
+  *yyvs= (YYSTYPE*) state->yacc_yyvs;
   return 0;
 }
 
@@ -6136,11 +6142,12 @@ void mysql_parse(THD *thd, const char *inBuf, uint length,
     sp_cache_flush_obsolete(&thd->sp_proc_cache);
     sp_cache_flush_obsolete(&thd->sp_func_cache);
 
-    Lex_input_stream lip(thd, inBuf, length);
-    thd->m_lip= &lip;
+    Parser_state parser_state(thd, inBuf, length);
+    thd->m_parser_state= &parser_state;
 
     int err= MYSQLparse(thd);
-    *found_semicolon= lip.found_semicolon;
+    *found_semicolon= parser_state.m_lip.found_semicolon;
+    thd->m_parser_state= NULL;
 
     if (!err && ! thd->is_fatal_error)
     {
@@ -6165,8 +6172,9 @@ void mysql_parse(THD *thd, const char *inBuf, uint length,
             PROCESSLIST.
             Note that we don't need LOCK_thread_count to modify query_length.
           */
-          if (lip.found_semicolon &&
-              (thd->query_length= (ulong)(lip.found_semicolon - thd->query)))
+          if (parser_state.m_lip.found_semicolon &&
+              (thd->query_length= (ulong)(parser_state.m_lip.found_semicolon
+                                          - thd->query)))
             thd->query_length--;
           /* Actually execute the query */
           if (*found_semicolon)
@@ -6225,11 +6233,13 @@ bool mysql_test_parse_for_slave(THD *thd, char *inBuf, uint length)
   bool error= 0;
   DBUG_ENTER("mysql_test_parse_for_slave");
 
-  Lex_input_stream lip(thd, inBuf, length);
-  thd->m_lip= &lip;
+  Parser_state parser_state(thd, inBuf, length);
+  thd->m_parser_state= &parser_state;
+
   lex_start(thd);
   mysql_reset_thd_for_next_command(thd);
   int err= MYSQLparse((void*) thd);
+  thd->m_parser_state= NULL;
 
   if (!err && ! thd->is_fatal_error &&
       all_tables_not_ok(thd,(TABLE_LIST*) lex->select_lex.table_list.first))
@@ -7295,7 +7305,7 @@ bool check_simple_select()
   if (lex->current_select != &lex->select_lex)
   {
     char command[80];
-    Lex_input_stream *lip= thd->m_lip;
+    Lex_input_stream *lip= & thd->m_parser_state->m_lip;
     strmake(command, lip->yylval->symbol.str,
 	    min(lip->yylval->symbol.length, sizeof(command)-1));
     my_error(ER_CANT_USE_OPTION_HERE, MYF(0), command);

sql/sql_prepare.cc

@@ -2849,12 +2849,13 @@ bool Prepared_statement::prepare(const char *packet, uint packet_len)
   old_stmt_arena= thd->stmt_arena;
   thd->stmt_arena= this;
 
-  Lex_input_stream lip(thd, thd->query, thd->query_length);
-  lip.stmt_prepare_mode= TRUE;
-  thd->m_lip= &lip;
+  Parser_state parser_state(thd, thd->query, thd->query_length);
+  parser_state.m_lip.stmt_prepare_mode= TRUE;
+  thd->m_parser_state= &parser_state;
   lex_start(thd);
   lex->safe_to_cache_query= FALSE;
   int err= MYSQLparse((void *)thd);
+  thd->m_parser_state= NULL;
   lex->set_trg_event_type_for_tables();
 
   error= err || thd->is_fatal_error ||

sql/sql_trigger.cc

@@ -968,11 +968,13 @@ bool Table_triggers_list::check_n_load(THD *thd, const char *db,
 
         thd->variables.sql_mode= (ulong)*trg_sql_mode;
 
-        Lex_input_stream lip(thd, trg_create_str->str, trg_create_str->length);
-        thd->m_lip= &lip;
+        Parser_state parser_state(thd, trg_create_str->str,
+                                  trg_create_str->length);
+        thd->m_parser_state= &parser_state;
         lex_start(thd);
         thd->spcont= NULL;
         int err= MYSQLparse((void *)thd);
+        thd->m_parser_state= NULL;
 
         if (err || thd->is_fatal_error)
         {

sql/sql_view.cc

@@ -1081,8 +1081,7 @@ bool mysql_make_view(THD *thd, File_parser *parser, TABLE_LIST *table,
     char old_db_buf[NAME_LEN+1];
     LEX_STRING old_db= { old_db_buf, sizeof(old_db_buf) };
     bool dbchanged;
-    Lex_input_stream lip(thd, table->query.str, table->query.length);
-    thd->m_lip= &lip;
+    Parser_state parser_state(thd, table->query.str, table->query.length);
 
     /* 
       Use view db name as thread default database, in order to ensure
@@ -1091,6 +1090,7 @@ bool mysql_make_view(THD *thd, File_parser *parser, TABLE_LIST *table,
     if ((result= sp_use_new_db(thd, table->view_db, &old_db, 1, &dbchanged)))
       goto end;
 
+    thd->m_parser_state= &parser_state;
     lex_start(thd);
     view_select= &lex->select_lex;
     view_select->select_number= ++thd->select_number;
@@ -1125,6 +1125,7 @@ bool mysql_make_view(THD *thd, File_parser *parser, TABLE_LIST *table,
     CHARSET_INFO *save_cs= thd->variables.character_set_client;
     thd->variables.character_set_client= system_charset_info;
     res= MYSQLparse((void *)thd);
+    thd->m_parser_state= NULL;
 
     if ((old_lex->sql_command == SQLCOM_SHOW_FIELDS) ||
         (old_lex->sql_command == SQLCOM_SHOW_CREATE))

sql/sql_yacc.yy

@@ -23,6 +23,7 @@
 #define YYPARSE_PARAM yythd
 #define YYLEX_PARAM yythd
 #define YYTHD ((THD *)yythd)
+#define YYLIP (& YYTHD->m_parser_state->m_lip)
 
 #define MYSQL_YACC
 #define YYINITDEPTH 100
@@ -86,7 +87,7 @@ const LEX_STRING null_lex_str={0,0};
 void my_parse_error(const char *s)
 {
   THD *thd= current_thd;
-  Lex_input_stream *lip= thd->m_lip;
+  Lex_input_stream *lip= & thd->m_parser_state->m_lip;
 
   const char *yytext= lip->tok_start;
   /* Push an error into the error stack */
@@ -1213,11 +1214,11 @@ query:
               MYSQL_YYABORT;
             }
             thd->lex->sql_command= SQLCOM_EMPTY_QUERY;
-            thd->m_lip->found_semicolon= NULL;
+            YYLIP->found_semicolon= NULL;
           }
         | verb_clause
           {
-            Lex_input_stream *lip = YYTHD->m_lip;
+            Lex_input_stream *lip = YYLIP;
 
             if ((YYTHD->client_capabilities & CLIENT_MULTI_QUERIES) &&
                 ! lip->stmt_prepare_mode &&
@@ -1243,7 +1244,7 @@ query:
         | verb_clause END_OF_INPUT
           {
             /* Single query, not terminated. */
-            YYTHD->m_lip->found_semicolon= NULL;
+            YYLIP->found_semicolon= NULL;
           }
         ;
 
@@ -2155,7 +2156,7 @@ sp_proc_stmt:
 	  {
             THD *thd= YYTHD;
 	    LEX *lex= thd->lex;
-            Lex_input_stream *lip= thd->m_lip;
+            Lex_input_stream *lip= YYLIP;
 
 	    if (lex->sphead->reset_lex(thd))
               MYSQL_YYABORT;
@@ -2165,7 +2166,7 @@ sp_proc_stmt:
 	  {
             THD *thd= YYTHD;
 	    LEX *lex= thd->lex;
-            Lex_input_stream *lip= thd->m_lip;
+            Lex_input_stream *lip= YYLIP;
 	    sp_head *sp= lex->sphead;
 
             sp->m_flags|= sp_get_flags_for_command(lex);
@@ -4503,16 +4504,12 @@ select_item:
 
 remember_name:
 	{
-          THD *thd= YYTHD;
-          Lex_input_stream *lip= thd->m_lip;
-          $$= (char*) lip->tok_start;
+          $$= (char*) YYLIP->tok_start;
         };
 
 remember_end:
 	{
-          THD *thd= YYTHD;
-          Lex_input_stream *lip= thd->m_lip;
-          $$=(char*) lip->tok_end;
+          $$=(char*) YYLIP->tok_end;
         };
 
 select_item2:
@@ -6452,7 +6449,7 @@ procedure_item:
 	  remember_name expr
 	  {
             THD *thd= YYTHD;
-            Lex_input_stream *lip= thd->m_lip;
+            Lex_input_stream *lip= YYLIP;
 
 	    if (add_proc_to_list(thd, $2))
 	      MYSQL_YYABORT;
@@ -7524,7 +7521,7 @@ load:   LOAD DATA_SYM
         {
           THD *thd= YYTHD;
           LEX *lex= thd->lex;
-          Lex_input_stream *lip= thd->m_lip;
+          Lex_input_stream *lip= YYLIP;
 
 	  if (lex->sphead)
 	  {
@@ -7566,10 +7563,7 @@ load_data:
         }
         opt_duplicate INTO
         {
-          THD *thd= YYTHD;
-	  LEX *lex= thd->lex;
-          Lex_input_stream *lip= thd->m_lip;
-	  lex->fname_end= lip->ptr;
+	  Lex->fname_end= YYLIP->ptr;
 	}
         TABLE_SYM table_ident
         {
@@ -7787,7 +7781,7 @@ param_marker:
         {
           THD *thd= YYTHD;
 	  LEX *lex= thd->lex;
-          Lex_input_stream *lip= thd->m_lip;
+          Lex_input_stream *lip= YYLIP;
           Item_param *item;
           if (! lex->parsing_options.allows_variable)
           {
@@ -7820,7 +7814,7 @@ literal:
 	| NULL_SYM
           {
             $$ = new Item_null();
-            YYTHD->m_lip->next_state=MY_LEX_OPERATOR_OR_IDENT;
+            YYLIP->next_state= MY_LEX_OPERATOR_OR_IDENT;
           }
 	| FALSE_SYM	{ $$= new Item_int((char*) "FALSE",0,1); }
 	| TRUE_SYM	{ $$= new Item_int((char*) "TRUE",1,1); }
@@ -7924,7 +7918,7 @@ simple_ident:
 	{
           THD *thd= YYTHD;
 	  LEX *lex= thd->lex;
-          Lex_input_stream *lip= thd->m_lip;
+          Lex_input_stream *lip= YYLIP;
 	  sp_variable_t *spv;
           sp_pcontext *spc = lex->spcont;
 	  if (spc && (spv = spc->find_variable(&$1)))
@@ -8537,7 +8531,7 @@ option_type_value:
         {
           THD *thd= YYTHD;
 	  LEX *lex= thd->lex;
-          Lex_input_stream *lip= thd->m_lip;
+          Lex_input_stream *lip= YYLIP;
 
           if (lex->sphead)
           {
@@ -8568,7 +8562,7 @@ option_type_value:
         {
           THD *thd= YYTHD;
 	  LEX *lex= thd->lex;
-          Lex_input_stream *lip= thd->m_lip;
+          Lex_input_stream *lip= YYLIP;
 
           if (lex->sphead)
           {
@@ -9878,7 +9872,7 @@ trigger_tail:
 	{
           THD *thd= YYTHD;
 	  LEX *lex= thd->lex;
-          Lex_input_stream *lip= thd->m_lip;
+          Lex_input_stream *lip= YYLIP;
 	  sp_head *sp;
 	 
 	  if (lex->sphead)
@@ -9971,7 +9965,7 @@ sf_tail:
           { /* $5 */
             THD *thd= YYTHD;
 	    LEX *lex= thd->lex;
-            Lex_input_stream *lip= thd->m_lip;
+            Lex_input_stream *lip= YYLIP;
 	    sp_head *sp;
 
 	    lex->stmt_definition_begin= $1;
@@ -9996,11 +9990,7 @@ sf_tail:
           sp_fdparam_list /* $6 */
           ')' /* $7 */
           { /* $8 */
-            THD *thd= YYTHD;
-	    LEX *lex= thd->lex;
-            Lex_input_stream *lip= thd->m_lip;
-
-	    lex->sphead->m_param_end= lip->tok_start;
+	    Lex->sphead->m_param_end= YYLIP->tok_start;
 	  }
           RETURNS_SYM /* $9 */
 	  { /* $10 */
@@ -10026,7 +10016,7 @@ sf_tail:
           { /* $14 */
             THD *thd= YYTHD;
 	    LEX *lex= thd->lex;
-            Lex_input_stream *lip= thd->m_lip;
+            Lex_input_stream *lip= YYLIP;
 
 	    lex->sphead->m_chistics= &lex->sp_chistics;
 	    lex->sphead->m_body_begin= lip->tok_start;
@@ -10078,18 +10068,14 @@ sp_tail:
 	}
         '('
 	{
-          THD *thd= YYTHD;
-	  LEX *lex= thd->lex;
-          Lex_input_stream *lip= thd->m_lip;
-
-	  lex->sphead->m_param_begin= lip->tok_start+1;
+	  Lex->sphead->m_param_begin= YYLIP->tok_start+1;
 	}
 	sp_pdparam_list
 	')'
 	{
           THD *thd= YYTHD;
 	  LEX *lex= thd->lex;
-          Lex_input_stream *lip= thd->m_lip;
+          Lex_input_stream *lip= YYLIP;
 
 	  lex->sphead->m_param_end= lip->tok_start;
 	  bzero((char *)&lex->sp_chistics, sizeof(st_sp_chistics));
@@ -10098,7 +10084,7 @@ sp_tail:
 	{
           THD *thd= YYTHD;
 	  LEX *lex= thd->lex;
-          Lex_input_stream *lip= thd->m_lip;
+          Lex_input_stream *lip= YYLIP;
 
 	  lex->sphead->m_chistics= &lex->sp_chistics;
 	  lex->sphead->m_body_begin= lip->tok_start;