fix double free related to ITS#6720

servers/slapd/overlays/rwm.c

@@ -598,7 +598,7 @@ rwm_op_modify( Operation *op, SlapReply *rs )
 					&mapping, RWM_MAP );
 			if ( drop_missing || ( mapping != NULL && BER_BVISNULL( &mapping->m_dst ) ) )
 			{
-				goto cleanup_mod;
+				goto skip_mod;
 			}
 		}
 
@@ -693,6 +693,10 @@ next_mod:;
 		mlp = &ml->sml_next;
 		continue;
 
+skip_mod:;
+		*mlp = (*mlp)->sml_next;
+		continue;
+
 cleanup_mod:;
 		ml = *mlp;
 		*mlp = (*mlp)->sml_next;