bk commit into 5.0 tree (evgen:1.2080) BUG#17366

[eugene]

Below is the list of changes that have just been committed into a local
5.0 repository of evgen. When evgen does a push these changes will
be propagated to the main repository and, within 24 hours after the
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ChangeSet
  1.2080 06/03/01 16:12:30 evgen@stripped +3 -0
  Fixed bug#17366: Unchecked Item_int results in server crash
  
  When there is conjunction of conds, the substitute_for_best_equal_field()
  will call the eliminate_item_equal() function in loop to build final
  expression. But if eliminate_item_equal() finds that some cond will always
  evaluate to 0, then that cond will be substituted by Item_int with value ==
  0. In this case on the next iteration eliminate_item_equal() will get that 
  Item_int and treat it as Item_cond. This is leads to memory corruption and
  server crash on cleanup phase.
  
  To the eliminate_item_equal() function was added DBUG_ASSERT for checking
  that all items treaten as Item_cond are really Item_cond.
  The substitute_for_best_equal_field() now checks that if
  eliminate_item_equal() returns Item_int and it's value is 0 then this 
  value is returned as the result of whole conjunction.

  sql/sql_select.cc
    1.396 06/03/01 16:11:22 evgen@stripped +9 -1
    Fixed bug#17366: Unchecked Item_int results in server crash
     
    To the eliminate_item_equal() function was added DBUG_ASSERT for checking
    that all items treaten as Item_cond are really Item_cond.
    The substitute_for_best_equal_field() now checks that if
    eliminate_item_equal() returns Item_int and it's value is 0 then this 
    value is returned as the result of whole conjunction.

  mysql-test/r/subselect.result
    1.135 06/03/01 16:11:07 evgen@stripped +7 -0
     Added test for bug#17366: Unchecked Item_int results in server crash

  mysql-test/t/subselect.test
    1.114 06/03/01 16:10:38 evgen@stripped +7 -0
    Added test for bug#17366: Unchecked Item_int results in server crash

# This is a BitKeeper patch.  What follows are the unified diffs for the
# set of deltas contained in the patch.  The rest of the patch, the part
# that BitKeeper cares about, is below these diffs.
# User:	evgen
# Host:	moonbone.local
# Root:	/work/17336-bug-5.0-mysql

--- 1.395/sql/sql_select.cc	2006-02-20 04:25:59 +03:00
+++ 1.396/sql/sql_select.cc	2006-03-01 16:11:22 +03:00
@@ -7066,7 +7066,10 @@
   if (!cond)
     cond= new Item_cond_and(eq_list);
   else
+  {
+    DBUG_ASSERT(cond->type() == Item::COND_ITEM);
     ((Item_cond *) cond)->add_at_head(&eq_list);
+  }
 
   cond->quick_fix_field();
   cond->update_used_tables();
@@ -7150,7 +7153,12 @@
       List_iterator_fast<Item_equal> it(cond_equal->current_level);
       while ((item_equal= it++))
       {
-        cond= eliminate_item_equal(cond, cond_equal->upper_levels, item_equal);
+        cond= eliminate_item_equal(cond, cond_equal->upper_levels,
+                                       item_equal);
+        // Due to 'AND' nature, if the result at some stage == 0,
+        // the whole cond_equal will be 0. In this case just return it.
+        if (cond->type() == Item::INT_ITEM && !cond->val_int())
+          break;
       }
     }
   }

--- 1.134/mysql-test/r/subselect.result	2006-02-20 04:25:59 +03:00
+++ 1.135/mysql-test/r/subselect.result	2006-03-01 16:11:07 +03:00
@@ -3157,3 +3157,10 @@
 1	PRIMARY	t1	ALL	NULL	NULL	NULL	NULL	9	Using where
 2	DEPENDENT SUBQUERY	t1	index	NULL	a	8	NULL	9	Using filesort
 DROP TABLE t1;
+create table t1( f1 int,f2 int);
+insert into t1 values (1,1),(2,2);
+select tt.t from (select 'crash1' as t, f2 from t1) as tt left join t1 on tt.t = 'crash2' and tt.f2 = t1.f2 where tt.t = 'crash1';
+t
+crash1
+crash1
+drop table t1;

--- 1.113/mysql-test/t/subselect.test	2006-02-14 05:50:00 +03:00
+++ 1.114/mysql-test/t/subselect.test	2006-03-01 16:10:38 +03:00
@@ -2073,3 +2073,10 @@
 
 DROP TABLE t1;
 
+#
+# Bug#17366: Unchecked Item_int results in server crash
+#
+create table t1( f1 int,f2 int);
+insert into t1 values (1,1),(2,2);
+select tt.t from (select 'crash1' as t, f2 from t1) as tt left join t1 on tt.t = 'crash2' and tt.f2 = t1.f2 where tt.t = 'crash1';
+drop table t1;