CHANGES

@@ -8,6 +8,7 @@ OpenLDAP 2.4.52 Engineering
 	Fixed libldap hang when using UDP and server down (ITS#9328)
 	Fixed slapd syncrepl rare deadlock due to network issues (ITS#9324)
 	Fixed slapd syncrepl regression that could trigger an assert (ITS#9329)
+	Fixed slapd-mdb index error with collapsed range (ITS#9135)
 
 OpenLDAP 2.4.51 Release (2020/08/11)
 	Added slapo-ppolicy implement Netscape password policy controls (ITS#9279)

servers/slapd/back-mdb/idl.c

@@ -625,9 +625,30 @@ mdb_idl_delete_keys(
 				}
 				if ( lo2 >= hi2 ) {
 				/* The range has collapsed... */
-					rc = mdb_cursor_del( cursor, MDB_NODUPDATA );
+					/* delete the range marker */
+					rc = mdb_cursor_del( cursor, 0 );
+					if ( rc != 0 ) {
+						err = "c_del dup1";
+						goto fail;
+					}
+					/* skip past deleted marker */
+					rc = mdb_cursor_get( cursor, &key, &data, MDB_NEXT_DUP );
+					if ( rc != 0 ) {
+						err = "c_get dup1";
+						goto fail;
+					}
+					/* delete the requested id */
+					if ( id == hi ) {
+						/* skip lo */
+						rc = mdb_cursor_get( cursor, &key, &data, MDB_NEXT_DUP );
+						if ( rc != 0 ) {
+							err = "c_get dup2";
+							goto fail;
+						}
+					}
+					rc = mdb_cursor_del( cursor, 0 );
 					if ( rc != 0 ) {
-						err = "c_del dup";
+						err = "c_del dup2";
 						goto fail;
 					}
 				} else {