mirror of
https://github.com/MariaDB/server.git
synced 2025-07-02 14:22:51 +03:00
086130e3c0
Original revid: alexey.kopytov@sun.com-20100723115254-jjwmhq97b9wl932l > Bug #54476: crash when group_concat and 'with rollup' in > prepared statements > > Using GROUP_CONCAT() together with the WITH ROLLUP modifier > could crash the server. > > The reason was a combination of several facts: > > 1. The Item_func_group_concat class stores pointers to ORDER > objects representing the columns in the ORDER BY clause of > GROUP_CONCAT(). > > 2. find_order_in_list() called from > Item_func_group_concat::setup() modifies the ORDER objects so > that their 'item' member points to the arguments list > allocated in the Item_func_group_concat constructor. > > 3. In some cases (e.g. in JOIN::rollup_make_fields) a copy of > the original Item_func_group_concat object could be created by > using the Item_func_group_concat::Item_func_group_concat(THD > *thd, Item_func_group_concat *item) copy constructor. The > latter essentially creates a shallow copy of the source > object. Memory for the arguments array is allocated on > thd->mem_root, but the pointers for arguments and ORDER are > copied verbatim. > > What happens in the test case is that when executing the query > for the first time, after a copy of the original > Item_func_group_concat object has been created by > JOIN::rollup_make_fields(), find_order_in_list() is called for > this new object. It then resolves ORDER BY by modifying the > ORDER objects so that they point to elements of the arguments > array which is local to the cloned object. When thd->mem_root > is freed upon completing the execution, pointers in the ORDER > objects become invalid. Those ORDER objects, however, are also > shared with the original Item_func_group_concat object which is > preserved between executions of a prepared statement. So the > first call to find_order_in_list() for the original object on > the second execution tries to dereference an invalid pointer. > > The solution is to create copies of the ORDER objects when > copying Item_func_group_concat to not leave any stale pointers > in other instances with different lifecycles. mysql-test/r/func_gconcat.result: Test case for bug #54476. mysql-test/t/func_gconcat.test: Test case for bug #54476. sql/item_sum.cc: Copy the ORDER objects pointed to by the elements of the 'order' array in the copy constructor of Item_func_group_concat. sql/table.h: Removed the unused 'item_copy' member of the ORDER class.
This directory contains a test suite for the MySQL daemon. To run the currently existing test cases, simply execute ./mysql-test-run in this directory. It will fire up the newly built mysqld and test it. Note that you do not have to have to do "make install", and you could actually have a co-existing MySQL installation. The tests will not conflict with it. All tests must pass. If one or more of them fail on your system, please read the following manual section for instructions on how to report the problem: http://dev.mysql.com/doc/mysql/en/mysql-test-suite.html If you want to use an already running MySQL server for specific tests, use the --extern option to mysql-test-run. Please note that in this mode, the test suite expects you to provide the names of the tests to run. For example, here is the command to run the "alias" and "analyze" tests with an external server: mysql-test-run --extern alias analyze To match your setup, you might also need to provide --socket, --user, and other relevant options. With no test cases named on the command line, mysql-test-run falls back to the normal "non-extern" behavior. The reason for this is that some tests cannot run with an external server. You can create your own test cases. To create a test case, create a new file in the t subdirectory using a text editor. The file should have a .test extension. For example: xemacs t/test_case_name.test In the file, put a set of SQL statements that create some tables, load test data, and run some queries to manipulate it. We would appreciate it if you name your test tables t1, t2, t3 ... (to not conflict too much with existing tables). Your test should begin by dropping the tables you are going to create and end by dropping them again. This ensures that you can run the test over and over again. If you are using mysqltest commands (like result file names) in your test case, you should create the result file as follows: mysql-test-run --record test_case_name or mysqltest --record < t/test_case_name.test If you only have a simple test cases consisting of SQL statements and comments, you can create the test case in one of the following ways: mysql-test-run --record test_case_name mysql test < t/test_case_name.test > r/test_case_name.result mysqltest --record --record-file=r/test_case_name.result < t/test_case_name.test When this is done, take a look at r/test_case_name.result - If the result is incorrect, you have found a bug. In this case, you should edit the test result to the correct results so that we can verify that the bug is corrected in future releases. To submit your test case, put your .test file and .result file(s) into a tar.gz archive, add a README that explains the problem, ftp the archive to ftp://support.mysql.com/pub/mysql/secret/ and send a mail to bugs@lists.mysql.com