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table and view...
Invalid memory reads after a query referencing MyISAM table
multiple times with write lock. Invalid memory reads may
lead to server crash, valgrind warnings, incorrect values
in INFORMATION_SCHEMA.TABLES.{TABLE_ROWS, DATA_LENGTH,
INDEX_LENGTH, ...}.
This may happen when one of the table instances gets closed
after a query, e.g. out of slots in open tables cache. UNION,
MERGE and VIEW are irrelevant.
The problem was that MyISAM didn't restore state info
pointer to default value.
myisam/mi_locking.c:
When a query is referencing MyISAM table multiple times
with a write lock, all table instances share the same
state info, pointing to MI_INFO::save_state of
"primary" table instance.
When lock is released, state pointer was restored only
for the primary table instance. Secondary table instances
are still pointing to save_state of primary table
instance.
Primary table instance may get closed, leaving secondary
table instances state pointer pointing to freed memory.
That's mostly ok, since next lock will update state info
pointer to correct value. But there're some cases, when
this secondary table instance state info is accessed
without a lock, e.g. INFORMATION_SCHEMA, MERGE (in 5.1
and up), MyISAM itself for DBUG purposes.
Restore default value of state pointer unconditionally,
for both primary and secondary table instances.
mysql-test/r/myisam.result:
A test case for BUG#48438.
mysql-test/t/myisam.test:
A test case for BUG#48438.
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