From fa54d0ce631d29343d04b8dcea8ef8d9c235feb3 Mon Sep 17 00:00:00 2001
From: William Brown <firstyear@redhat.com>
Date: Dec 16 2016 16:52:22 +0000
Subject: Ticket 48665 - Prevent sefault in ldbm_instance_modify_config_entry


Bug Description:  python ldap sends a mod_delete then a mod_add to the server.
This causes a segfault in ldbm_instance_modify_config_entry which expects the
value of the delete operation to exist.

Fix Description:  If there is no attribute in the delete operation, this now
passes a NULL to ldbm_config_set, which then rejects the op as NO_SUCH_ATTRIBUTE

There is an attached test case, which also checks that mod_replace is still
functional.

https://fedorahosted.org/389/ticket/48665

Author: wibrown

Review by: nhosoi (Thanks!)

(cherry picked from commit 9134b006948d7d8eeb926655640b7f068fc6724d)

---

diff --git a/dirsrvtests/tests/tickets/ticket48665_test.py b/dirsrvtests/tests/tickets/ticket48665_test.py
new file mode 100644
index 0000000..702319c
--- /dev/null
+++ b/dirsrvtests/tests/tickets/ticket48665_test.py
@@ -0,0 +1,101 @@
+import os
+import sys
+import time
+import ldap
+import logging
+import pytest
+from lib389 import DirSrv, Entry, tools, tasks
+from lib389.tools import DirSrvTools
+from lib389._constants import *
+from lib389.properties import *
+from lib389.tasks import *
+from lib389.utils import *
+
+logging.getLogger(__name__).setLevel(logging.DEBUG)
+log = logging.getLogger(__name__)
+
+class TopologyStandalone(object):
+    def __init__(self, standalone):
+        standalone.open()
+        self.standalone = standalone
+
+
+@pytest.fixture(scope="module")
+def topology(request):
+    # Creating standalone instance ...
+    standalone = DirSrv(verbose=False)
+    args_instance[SER_HOST] = HOST_STANDALONE
+    args_instance[SER_PORT] = PORT_STANDALONE
+    args_instance[SER_SERVERID_PROP] = SERVERID_STANDALONE
+    args_instance[SER_CREATION_SUFFIX] = DEFAULT_SUFFIX
+    args_standalone = args_instance.copy()
+    standalone.allocate(args_standalone)
+    instance_standalone = standalone.exists()
+    if instance_standalone:
+        standalone.delete()
+    standalone.create()
+    standalone.open()
+
+    # Delete each instance in the end
+    def fin():
+        # This is useful for analysing the test env.
+        #standalone.db2ldif(bename=DEFAULT_BENAME, suffixes=[DEFAULT_SUFFIX], excludeSuffixes=[], encrypt=False, \
+        #    repl_data=True, outputfile='%s/ldif/%s.ldif' % (standalone.dbdir,SERVERID_STANDALONE ))
+        #standalone.clearBackupFS()
+        #standalone.backupFS()
+        standalone.delete()
+    request.addfinalizer(fin)
+
+    # Clear out the tmp dir
+    standalone.clearTmpDir(__file__)
+
+    return TopologyStandalone(standalone)
+
+
+def test_ticket48665(topology):
+    """
+    This tests deletion of certain cn=config values.
+
+    First, it should be able to delete, and not crash the server.
+
+    Second, we might be able to delete then add to replace values.
+
+    We should also still be able to mod replace the values and keep the server alive.
+    """
+    #topology.standalone.config.enable_log('audit')
+    #topology.standalone.config.enable_log('auditfail')
+    # This will trigger a mod delete then add.
+    try:
+        modlist = [(ldap.MOD_DELETE, 'nsslapd-cachememsize', None), (ldap.MOD_ADD, 'nsslapd-cachememsize', '1')]
+        topology.standalone.modify_s("cn=%s,cn=ldbm database,cn=plugins,cn=config" % DEFAULT_BENAME,
+            modlist)
+    except:
+        pass
+    # Check the server has not commited seppuku.
+    result = topology.standalone.whoami_s()
+    assert(DN_DM.lower() in result.lower())
+
+    # This has a magic hack to determine if we are in cn=config.
+    topology.standalone.backend.setProperties(bename=DEFAULT_BENAME,
+        prop='nsslapd-cachememsize', values='1')
+    # Check the server has not commited seppuku.
+    result = topology.standalone.whoami_s()
+    assert(DN_DM.lower() in result.lower())
+
+    # Now try with mod_replace. This should be okay.
+
+    modlist = [(ldap.MOD_REPLACE, 'nsslapd-cachememsize', '1')]
+    topology.standalone.modify_s("cn=%s,cn=ldbm database,cn=plugins,cn=config" % DEFAULT_BENAME,
+        modlist)
+    # Check the server has not commited seppuku.
+    result = topology.standalone.whoami_s()
+    assert(DN_DM.lower() in result.lower())
+
+    log.info('Test complete')
+
+
+if __name__ == '__main__':
+    # Run isolated
+    # -s for DEBUG mode
+    CURRENT_FILE = os.path.realpath(__file__)
+    pytest.main("-s %s" % CURRENT_FILE)
diff --git a/ldap/servers/slapd/back-ldbm/ldbm_instance_config.c b/ldap/servers/slapd/back-ldbm/ldbm_instance_config.c
index 2037618..c269ab3 100644
--- a/ldap/servers/slapd/back-ldbm/ldbm_instance_config.c
+++ b/ldap/servers/slapd/back-ldbm/ldbm_instance_config.c
@@ -789,9 +789,19 @@ ldbm_instance_modify_config_entry_callback(Slapi_PBlock *pb, Slapi_Entry* entryB
             }
 
         /* This assumes there is only one bval for this mod. */
-            rc = ldbm_config_set((void *) inst, attr_name,
-                ldbm_instance_config, mods[i]->mod_bvalues[0], returntext,
-                CONFIG_PHASE_RUNNING, apply_mod, mods[i]->mod_op);
+            if (mods[i]->mod_bvalues == NULL) {
+                /* This avoids the null pointer deref.
+                 * In ldbm_config.c ldbm_config_set, it checks for the NULL.
+                 * If it's a NULL, we get NO_SUCH_ATTRIBUTE error.
+                 */
+                rc = ldbm_config_set((void *) inst, attr_name,
+                    ldbm_instance_config, NULL, returntext,
+                    CONFIG_PHASE_RUNNING, apply_mod, mods[i]->mod_op);
+            } else {
+                rc = ldbm_config_set((void *) inst, attr_name,
+                    ldbm_instance_config, mods[i]->mod_bvalues[0], returntext,
+                    CONFIG_PHASE_RUNNING, apply_mod, mods[i]->mod_op);
+            }
         }
     }