s4:dsdb Fix linked_attributes to cope with the Feb 2010 changes to DLIST

The DLIST macros changed in behaviour in Feb 2010, and walking the
lists backwards is no longer safe if you don't use the macros.

Andrew Bartlett

1 files changed, 6 insertions, 2 deletions

diff --git a/source4/dsdb/samdb/ldb_modules/linked_attributes.c b/source4/dsdb/samdb/ldb_modules/linked_attributes.c
index 4f36509a85..d2a435ef50 100644
--- a/source4/dsdb/samdb/ldb_modules/linked_attributes.c
+++ b/source4/dsdb/samdb/ldb_modules/linked_attributes.c
@@ -1039,9 +1039,13 @@ static int linked_attributes_prepare_commit(struct ldb_module *module)
 	/* walk the list backwards, to do the first entry first, as we
 	 * added the entries with DLIST_ADD() which puts them at the
 	 * start of the list */
-	for (ac = la_private->la_list; ac && ac->next; ac=ac->next) ;
 
-	for (; ac; ac=ac->prev) {
+	/* Start at the end of the list - so we can start
+	 * there, but ensure we don't create a loop by NULLing
+	 * it out in the first element */
+	ac = DLIST_TAIL(la_private->la_list);
+
+	for (; ac; ac=DLIST_PREV(ac)) {
 		int ret;
 		ac->req = NULL;
 		ret = la_do_mod_request(module, ac);