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BUG#51877 - HANDLER interface causes invalid memory read

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Invalid memory read if HANDLER ... READ NEXT is executed
after failed (e.g. empty table) HANDLER ... READ FIRST.

The problem was that we attempted to perform READ NEXT,
whereas there is no pivot available from failed READ FIRST.

With this fix READ NEXT after failed READ FIRST equals
to READ FIRST.

This bug affects MyISAM tables only.

mysql-test/r/gis-rtree.result:
  Restore a test case for BUG51357.
mysql-test/r/handler_myisam.result:
  A test case for BUG#51877.
mysql-test/t/gis-rtree.test:
  Restore a test case for BUG51357.
mysql-test/t/handler_myisam.test:
  A test case for BUG#51877.
storage/myisam/mi_rnext.c:
  "search first" failed. This means we have no pivot for
  "search next", or in other words MI_INFO::lastkey is
  likely uninitialized.
  
  Normally SQL layer would never request "search next" if
  "search first" failed. But HANDLER may do anything.
  
  As mi_rnext() without preceeding mi_rkey()/mi_rfirst()
  equals to mi_rfirst(), we must restore original state
  as if failing mi_rfirst() was not called.
This commit is contained in:
Sergey Vojtovich 2010-03-25 15:49:01 +04:00
commit b57ef6d3cd
5 changed files with 55 additions and 8 deletions
Download patch file Download diff file Expand all files Collapse all files

11
mysql-test/t/handler_myisam.test
View file

@ -37,4 +37,15 @@ TRUNCATE t1;
HANDLER t1 READ FIRST;
DROP TABLE t1;
--echo #
--echo # BUG#51877 - HANDLER interface causes invalid memory read
--echo #
CREATE TABLE t1(a INT, KEY(a));
HANDLER t1 OPEN;
HANDLER t1 READ a FIRST;
INSERT INTO t1 VALUES(1);
HANDLER t1 READ a NEXT;
HANDLER t1 CLOSE;
DROP TABLE t1;
--echo End of 5.1 tests