From b0d73083719f39a4a4f9664ce57208f7c29017db Mon Sep 17 00:00:00 2001
From: Howard Chu <hyc@openldap.org>
Date: Thu, 13 Aug 2020 18:17:45 +0100
Subject: [PATCH] ITS#9135 fix index error on collapsed range

---
 servers/slapd/back-mdb/idl.c | 25 +++++++++++++++++++++++--
 1 file changed, 23 insertions(+), 2 deletions(-)

diff --git a/servers/slapd/back-mdb/idl.c b/servers/slapd/back-mdb/idl.c
index b81ac84163..f7663167ed 100644
--- a/servers/slapd/back-mdb/idl.c
+++ b/servers/slapd/back-mdb/idl.c
@@ -642,9 +642,30 @@ 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 dup";
+						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 dup2";
 						goto fail;
 					}
 				} else {