Bug #20085672: CRYPTIC ERROR WHEN FAILING TO UNLOAD A DYNAMIC LIBRARY

gkodinov · gkodinov · commit ad3b185e5b7c · 2016-03-21T12:33:00.000+02:00
When the server loads a plugin it searches for globals of the
plugin services the plugin may be using. If found it expects a version
in these globals, checks the version and if it matches replaces it with a
pointer to the server function implementing the service.
It does not save these versions and thus does not restore them when
unloading the plugin, as it expects that the dynamic library will go away.
However if the same shared library also exports UDF functions the reference
count to it may not be zero and UNINSTALL PLUGIN will not actually unload
the shared library.
So the next INSTALL PLUGIN will find the shared library, but will fail when
checking the service versions since these are already replaced by the server
function pointers.

Fixed by accepting the relevant server function pointer as a valid value for
the version in addition to the actual version as checked currently.

Test case added.
diff --git a/mysql-test/include/plugin.defs b/mysql-test/include/plugin.defs
@@ -46,3 +46,4 @@ libmemcached       plugin/innodb_memcached/daemon_memcached DAEMON_MEMCACHED dae
 innodb_engine      plugin/innodb_memcached/innodb_memcache INNODB_ENGINE
 validate_password  plugin/password_validation VALIDATE_PASSWORD validate_password
 mysql_no_login     plugin/mysql_no_login      MYSQL_NO_LOGIN    mysql_no_login
+test_udf_services  plugin/udf_services TESTUDFSERVICES
diff --git a/mysql-test/r/udf_services.result b/mysql-test/r/udf_services.result
@@ -0,0 +1,15 @@
+#
+# Bug #20085672: CRYPTIC ERROR WHEN FAILING TO UNLOAD A DYNAMIC LIBRARY
+#
+# Install the plugin
+INSTALL PLUGIN test_udf_services SONAME 'TESTUDFSERVICES';
+# Define the function
+CREATE FUNCTION test_udf_services_udf RETURNS INT
+SONAME "TESTUDFSERVICES";
+# Uninstall the plugin
+UNINSTALL PLUGIN test_udf_services;
+# Install the plugin again. Should not fail
+INSTALL PLUGIN test_udf_services SONAME 'TESTUDFSERVICES';
+# Cleanup
+DROP FUNCTION test_udf_services_udf;
+UNINSTALL PLUGIN test_udf_services;
diff --git a/mysql-test/t/udf_services-master.opt b/mysql-test/t/udf_services-master.opt
@@ -0,0 +1 @@
+$TESTUDFSERVICES_OPT
diff --git a/mysql-test/t/udf_services.test b/mysql-test/t/udf_services.test
@@ -0,0 +1,25 @@
+--source include/not_embedded.inc
+
+--echo #
+--echo # Bug #20085672: CRYPTIC ERROR WHEN FAILING TO UNLOAD A DYNAMIC LIBRARY
+--echo #
+
+--echo # Install the plugin
+--replace_result $TESTUDFSERVICES TESTUDFSERVICES
+eval INSTALL PLUGIN test_udf_services SONAME '$TESTUDFSERVICES';
+
+--echo # Define the function
+--replace_result $TESTUDFSERVICES TESTUDFSERVICES
+eval CREATE FUNCTION test_udf_services_udf RETURNS INT
+  SONAME "$TESTUDFSERVICES";
+
+--echo # Uninstall the plugin
+UNINSTALL PLUGIN test_udf_services;
+
+--echo # Install the plugin again. Should not fail
+--replace_result $TESTUDFSERVICES TESTUDFSERVICES
+eval INSTALL PLUGIN test_udf_services SONAME '$TESTUDFSERVICES';
+
+--echo # Cleanup
+DROP FUNCTION test_udf_services_udf;
+UNINSTALL PLUGIN test_udf_services;
diff --git a/packaging/deb-jessie/source/include-binaries b/packaging/deb-jessie/source/include-binaries
@@ -1,4 +1,4 @@
-# Copyright (c) 2014, 2015, Oracle and/or its affiliates. All rights reserved.
+# Copyright (c) 2014, 2016, Oracle and/or its affiliates. All rights reserved.
 #
 # This program is free software; you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
@@ -30,4 +30,5 @@ debian/extra/qa_auth_interface-plugin
 debian/extra/qa_auth_server-plugin
 debian/extra/semisync_master-plugin
 debian/extra/semisync_slave-plugin
+debian/extra/test_udf_services-plugin
 debian/extra/validate_password-plugin
diff --git a/packaging/deb-precise/source/include-binaries b/packaging/deb-precise/source/include-binaries
@@ -1,4 +1,4 @@
-# Copyright (c) 2014, 2015, Oracle and/or its affiliates. All rights reserved.
+# Copyright (c) 2014, 2016, Oracle and/or its affiliates. All rights reserved.
 #
 # This program is free software; you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
@@ -30,4 +30,5 @@ debian/extra/qa_auth_interface-plugin
 debian/extra/qa_auth_server-plugin
 debian/extra/semisync_master-plugin
 debian/extra/semisync_slave-plugin
+debian/extra/test_udf_services-plugin
 debian/extra/validate_password-plugin
diff --git a/packaging/deb-trusty/source/include-binaries b/packaging/deb-trusty/source/include-binaries
@@ -1,4 +1,4 @@
-# Copyright (c) 2014, 2015, Oracle and/or its affiliates. All rights reserved.
+# Copyright (c) 2014, 2016, Oracle and/or its affiliates. All rights reserved.
 #
 # This program is free software; you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
@@ -30,4 +30,5 @@ debian/extra/qa_auth_interface-plugin
 debian/extra/qa_auth_server-plugin
 debian/extra/semisync_master-plugin
 debian/extra/semisync_slave-plugin
+debian/extra/test_udf_services-plugin
 debian/extra/validate_password-plugin
diff --git a/packaging/deb-utopic/source/include-binaries b/packaging/deb-utopic/source/include-binaries
@@ -1,4 +1,4 @@
-# Copyright (c) 2015, Oracle and/or its affiliates. All rights reserved.
+# Copyright (c) 2015, 2016, Oracle and/or its affiliates. All rights reserved.
 #
 # This program is free software; you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
@@ -30,4 +30,5 @@ debian/extra/qa_auth_interface-plugin
 debian/extra/qa_auth_server-plugin
 debian/extra/semisync_master-plugin
 debian/extra/semisync_slave-plugin
+debian/extra/test_udf_services-plugin
 debian/extra/validate_password-plugin
diff --git a/packaging/deb-vivid/source/include-binaries b/packaging/deb-vivid/source/include-binaries
@@ -1,4 +1,4 @@
-# Copyright (c) 2015, Oracle and/or its affiliates. All rights reserved.
+# Copyright (c) 2015, 2016, Oracle and/or its affiliates. All rights reserved.
 #
 # This program is free software; you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
@@ -30,4 +30,5 @@ debian/extra/qa_auth_interface-plugin
 debian/extra/qa_auth_server-plugin
 debian/extra/semisync_master-plugin
 debian/extra/semisync_slave-plugin
+debian/extra/test_udf_services-plugin
 debian/extra/validate_password-plugin
diff --git a/packaging/deb-wheezy/source/include-binaries b/packaging/deb-wheezy/source/include-binaries
@@ -1,4 +1,4 @@
-# Copyright (c) 2014, 2015, Oracle and/or its affiliates. All rights reserved.
+# Copyright (c) 2014, 2016, Oracle and/or its affiliates. All rights reserved.
 #
 # This program is free software; you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
@@ -30,4 +30,5 @@ debian/extra/qa_auth_interface-plugin
 debian/extra/qa_auth_server-plugin
 debian/extra/semisync_master-plugin
 debian/extra/semisync_slave-plugin
+debian/extra/test_udf_services-plugin
 debian/extra/validate_password-plugin
diff --git a/packaging/deb-wily/source/include-binaries b/packaging/deb-wily/source/include-binaries
@@ -1,4 +1,4 @@
-# Copyright (c) 2015, Oracle and/or its affiliates. All rights reserved.
+# Copyright (c) 2015, 2016, Oracle and/or its affiliates. All rights reserved.
 #
 # This program is free software; you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
@@ -30,4 +30,5 @@ debian/extra/qa_auth_interface-plugin
 debian/extra/qa_auth_server-plugin
 debian/extra/semisync_master-plugin
 debian/extra/semisync_slave-plugin
+debian/extra/test_udf_services-plugin
 debian/extra/validate_password-plugin
diff --git a/packaging/rpm-docker/mysql.spec.in b/packaging/rpm-docker/mysql.spec.in
@@ -1,4 +1,4 @@
-# Copyright (c) 2000, 2015, Oracle and/or its affiliates. All rights reserved.
+# Copyright (c) 2000, 2016, Oracle and/or its affiliates. All rights reserved.
 #
 # This program is free software; you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
@@ -189,7 +189,8 @@ done
 
 #  Remove test plugins
 for p in auth.so auth_test_plugin.so daemon_example.ini libdaemon_example.so qa_auth_client.so \
-    qa_auth_interface.so qa_auth_server.so replication_observers_example_plugin.so ha_example.so ; do
+    qa_auth_interface.so qa_auth_server.so replication_observers_example_plugin.so ha_example.so \
+    test_udf_services.so ; do
     rm -f %{buildroot}%{_libdir}/mysql/plugin/$p
 done
 
diff --git a/packaging/rpm-fedora/mysql.spec.in b/packaging/rpm-fedora/mysql.spec.in
@@ -1,4 +1,4 @@
-# Copyright (c) 2000, 2015, Oracle and/or its affiliates. All rights reserved.
+# Copyright (c) 2000, 2016, Oracle and/or its affiliates. All rights reserved.
 #
 # This program is free software; you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
@@ -679,12 +679,14 @@ datadir=$(/usr/bin/my_print_defaults server mysqld | grep '^--datadir=' | sed -n
 %attr(755, root, root) %{_libdir}/mysql/plugin/auth_test_plugin.so
 %attr(644, root, root) %{_libdir}/mysql/plugin/daemon_example.ini
 %attr(755, root, root) %{_libdir}/mysql/plugin/libdaemon_example.so
+%attr(755, root, root) %{_libdir}/mysql/plugin/test_udf_services.so
 %attr(755, root, root) %{_libdir}/mysql/plugin/qa_auth_client.so
 %attr(755, root, root) %{_libdir}/mysql/plugin/qa_auth_interface.so
 %attr(755, root, root) %{_libdir}/mysql/plugin/qa_auth_server.so
 %attr(755, root, root) %{_libdir}/mysql/plugin/debug/auth.so
 %attr(755, root, root) %{_libdir}/mysql/plugin/debug/auth_test_plugin.so
 %attr(755, root, root) %{_libdir}/mysql/plugin/debug/libdaemon_example.so
+%attr(755, root, root) %{_libdir}/mysql/plugin/debug/test_udf_services.so
 %attr(755, root, root) %{_libdir}/mysql/plugin/debug/qa_auth_client.so
 %attr(755, root, root) %{_libdir}/mysql/plugin/debug/qa_auth_interface.so
 %attr(755, root, root) %{_libdir}/mysql/plugin/debug/qa_auth_server.so
@@ -716,6 +718,9 @@ datadir=$(/usr/bin/my_print_defaults server mysqld | grep '^--datadir=' | sed -n
 %attr(755, root, root) %{_libdir}/mysql/libmysqld.so
 
 %changelog
+* Mon Mar 14 2015 Georgi Kodinov <georgi.kodinov@oracle.com> - 5.6.31-1
+- Add test_udf_services.so plugin
+
 * Wed Jan 14 2015 Balasubramanian Kandasamy <balasubramanian.kandasamy@oracle.com> - 5.6.24-1
 - Add mysql_no_login.so plugin
 
diff --git a/packaging/rpm-oel/mysql.spec.in b/packaging/rpm-oel/mysql.spec.in
@@ -1,4 +1,4 @@
-# Copyright (c) 2000, 2015, Oracle and/or its affiliates. All rights reserved.
+# Copyright (c) 2000, 2016, Oracle and/or its affiliates. All rights reserved.
 #
 # This program is free software; you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
@@ -765,12 +765,14 @@ fi
 %attr(755, root, root) %{_libdir}/mysql/plugin/auth_test_plugin.so
 %attr(644, root, root) %{_libdir}/mysql/plugin/daemon_example.ini
 %attr(755, root, root) %{_libdir}/mysql/plugin/libdaemon_example.so
+%attr(755, root, root) %{_libdir}/mysql/plugin/test_udf_services.so
 %attr(755, root, root) %{_libdir}/mysql/plugin/qa_auth_client.so
 %attr(755, root, root) %{_libdir}/mysql/plugin/qa_auth_interface.so
 %attr(755, root, root) %{_libdir}/mysql/plugin/qa_auth_server.so
 %attr(755, root, root) %{_libdir}/mysql/plugin/debug/auth.so
 %attr(755, root, root) %{_libdir}/mysql/plugin/debug/auth_test_plugin.so
 %attr(755, root, root) %{_libdir}/mysql/plugin/debug/libdaemon_example.so
+%attr(755, root, root) %{_libdir}/mysql/plugin/debug/test_udf_services.so
 %attr(755, root, root) %{_libdir}/mysql/plugin/debug/qa_auth_client.so
 %attr(755, root, root) %{_libdir}/mysql/plugin/debug/qa_auth_interface.so
 %attr(755, root, root) %{_libdir}/mysql/plugin/debug/qa_auth_server.so
@@ -949,6 +951,9 @@ fi
 %endif
 
 %changelog
+* Mon Mar 14 2015 Georgi Kodinov <georgi.kodinov@oracle.com> - 5.6.31-1
+- Add test_udf_services.so plugin
+
 * Tue Sep 29 2015 Balasubramanian Kandasamy <balasubramanian.kandasamy@oracle.com> - 5.6.28-1
 - Added conflicts to mysql-connector-c-shared dependencies
 
diff --git a/packaging/rpm-sles/mysql.spec.in b/packaging/rpm-sles/mysql.spec.in
@@ -1,4 +1,4 @@
-# Copyright (c) 2000, 2015, Oracle and/or its affiliates. All rights reserved.
+# Copyright (c) 2000, 2016, Oracle and/or its affiliates. All rights reserved.
 #
 # This program is free software; you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
@@ -781,12 +781,14 @@ fi
 %attr(755, root, root) %{_libdir}/mysql/plugin/auth_test_plugin.so
 %attr(644, root, root) %{_libdir}/mysql/plugin/daemon_example.ini
 %attr(755, root, root) %{_libdir}/mysql/plugin/libdaemon_example.so
+%attr(755, root, root) %{_libdir}/mysql/plugin/test_udf_services.so
 %attr(755, root, root) %{_libdir}/mysql/plugin/qa_auth_client.so
 %attr(755, root, root) %{_libdir}/mysql/plugin/qa_auth_interface.so
 %attr(755, root, root) %{_libdir}/mysql/plugin/qa_auth_server.so
 %attr(755, root, root) %{_libdir}/mysql/plugin/debug/auth.so
 %attr(755, root, root) %{_libdir}/mysql/plugin/debug/auth_test_plugin.so
 %attr(755, root, root) %{_libdir}/mysql/plugin/debug/libdaemon_example.so
+%attr(755, root, root) %{_libdir}/mysql/plugin/debug/test_udf_services.so
 %attr(755, root, root) %{_libdir}/mysql/plugin/debug/qa_auth_client.so
 %attr(755, root, root) %{_libdir}/mysql/plugin/debug/qa_auth_interface.so
 %attr(755, root, root) %{_libdir}/mysql/plugin/debug/qa_auth_server.so
@@ -818,6 +820,9 @@ fi
 %attr(755, root, root) %{_libdir}/mysql/libmysqld.so
 
 %changelog
+* Mon Mar 14 2015 Georgi Kodinov <georgi.kodinov@oracle.com> - 5.6.31-1
+- Add test_udf_services.so plugin
+
 * Tue Sep 29 2015 Balasubramanian Kandasamy <balasubramanian.kandasamy@oracle.com> - 5.6.28-1
 - Added conflicts to mysql-connector-c-shared dependencies
 
diff --git a/plugin/udf_services/CMakeLists.txt b/plugin/udf_services/CMakeLists.txt
@@ -0,0 +1,16 @@
+# Copyright (c) 2016, Oracle and/or its affiliates. All rights reserved.
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; version 2 of the License.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+
+MYSQL_ADD_PLUGIN(test_udf_services test_udf_services.cc MODULE_ONLY)
diff --git a/plugin/udf_services/test_udf_services.cc b/plugin/udf_services/test_udf_services.cc
@@ -0,0 +1,101 @@
+/* Copyright (c) 2016, Oracle and/or its affiliates. All rights reserved.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; version 2 of the License.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software
+   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA */
+
+#include <my_global.h>
+#include <mysql_version.h>
+#include <mysql/plugin.h>
+#include <mysql_com.h>
+
+/**
+  @file test_udf_services.cc
+
+  This is a test suite plugin to verify that plugins can co-exist with UDFs.
+  The file defines one DAEMON plugin @ref test_udf_services_plugin and one
+  UDF function: @ref test_udf_services_udf.
+  The test then checks if the plugin can be unloaded and loaded while the
+  UDF is defined.
+
+  No user-facing functionality in this plugin. Just test material !
+*/
+
+static struct st_mysql_daemon test_udf_services_plugin=
+{ MYSQL_DAEMON_INTERFACE_VERSION  };
+
+mysql_declare_plugin(test_udf_services)
+{
+  MYSQL_DAEMON_PLUGIN,
+  &test_udf_services_plugin,
+  "test_udf_services",
+  "Georgi Kodinov",
+  "MySQL mtr test framework",
+  PLUGIN_LICENSE_GPL,
+  NULL,                       /* Plugin Init          */
+  NULL,                       /* Plugin Deinit        */
+  0x0100,                     /* Plugin version: 1.0  */
+  NULL,                       /* status variables     */
+  NULL,                       /* system variables     */
+  NULL,                       /* config options       */
+  0,                          /* flags                */
+}
+mysql_declare_plugin_end;
+
+#ifdef WIN32
+#define PLUGIN_EXPORT extern "C" __declspec(dllexport)
+#else
+#define PLUGIN_EXPORT extern "C"
+#endif
+
+
+/**
+  Initialization function for @ref test_udf_services_udf
+
+  Must be present otherwise the server refuses to load
+
+  @param      initrd    Return value from xxxx_init
+  @param      args      Array of arguments
+  @param[out] message   Error message in case of error.
+  @retval     FALSE     success
+  @retval     TRUE      Failure. Error in the message argument
+*/
+PLUGIN_EXPORT my_bool
+test_udf_services_udf_init(UDF_INIT *initid __attribute__((unused)),
+                           UDF_ARGS *args __attribute__((unused)),
+                           char *message __attribute__((unused)))
+{
+  return FALSE;
+}
+
+
+/**
+  A UDF function returning 0.
+
+  @param      initrd    Return value from xxxx_init
+  @param      args      Array of arguments
+  @param[out] is_null   If the result is null, store 1 here
+  @param[out] error     On error store 1 here
+*/
+PLUGIN_EXPORT longlong
+test_udf_services_udf(UDF_INIT *initid __attribute__((unused)),
+                      UDF_ARGS *args __attribute__((unused)),
+                      char *is_null __attribute__((unused)),
+                      char *error __attribute__((unused)))
+{
+  char buffer[10];
+  *is_null= 0;
+  *error= 0;
+  /* use a plugin service function */
+  my_snprintf(buffer, sizeof(buffer), "test");
+  return 0;
+}
diff --git a/sql/sql_plugin.cc b/sql/sql_plugin.cc
@@ -1,5 +1,5 @@
 /*
-   Copyright (c) 2005, 2015, Oracle and/or its affiliates. All rights reserved.
+   Copyright (c) 2005, 2016, Oracle and/or its affiliates. All rights reserved.
 
    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -528,8 +528,9 @@ static st_plugin_dl *plugin_dl_add(const LEX_STRING *dl, int report)
     if ((sym= dlsym(plugin_dl.handle, list_of_services[i].name)))
     {
       uint ver= (uint)(intptr)*(void**)sym;
-      if (ver > list_of_services[i].version ||
-        (ver >> 8) < (list_of_services[i].version >> 8))
+      if ((*(void**)sym) != list_of_services[i].service && /* already replaced */
+          (ver > list_of_services[i].version ||
+           (ver >> 8) < (list_of_services[i].version >> 8)))
       {
         char buf[MYSQL_ERRMSG_SIZE];
         my_snprintf(buf, sizeof(buf),
