From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on dcvr.yhbt.net X-Spam-Level: X-Spam-ASN: AS31976 209.132.180.0/23 X-Spam-Status: No, score=-4.0 required=3.0 tests=AWL,BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI shortcircuit=no autolearn=ham autolearn_force=no version=3.4.2 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by dcvr.yhbt.net (Postfix) with ESMTP id EE8B91F87F for ; Tue, 20 Nov 2018 09:46:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726917AbeKTUOy (ORCPT ); Tue, 20 Nov 2018 15:14:54 -0500 Received: from cloud.peff.net ([104.130.231.41]:45466 "HELO cloud.peff.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1726250AbeKTUOx (ORCPT ); Tue, 20 Nov 2018 15:14:53 -0500 Received: (qmail 21328 invoked by uid 109); 20 Nov 2018 09:46:40 -0000 Received: from Unknown (HELO peff.net) (10.0.1.2) by cloud.peff.net (qpsmtpd/0.94) with SMTP; Tue, 20 Nov 2018 09:46:40 +0000 Authentication-Results: cloud.peff.net; auth=none Received: (qmail 27020 invoked by uid 111); 20 Nov 2018 09:46:02 -0000 Received: from sigill.intra.peff.net (HELO sigill.intra.peff.net) (10.0.0.7) by peff.net (qpsmtpd/0.94) with (ECDHE-RSA-AES256-GCM-SHA384 encrypted) SMTP; Tue, 20 Nov 2018 04:46:02 -0500 Authentication-Results: peff.net; auth=none Received: by sigill.intra.peff.net (sSMTP sendmail emulation); Tue, 20 Nov 2018 04:46:38 -0500 Date: Tue, 20 Nov 2018 04:46:38 -0500 From: Jeff King To: git@vger.kernel.org Cc: Christian Couder , Derrick Stolee Subject: [PATCH 1/3] pack-objects: fix tree_depth and layer invariants Message-ID: <20181120094638.GA22742@sigill.intra.peff.net> References: <20181120094451.GA21725@sigill.intra.peff.net> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20181120094451.GA21725@sigill.intra.peff.net> Sender: git-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org Commit 108f530385 (pack-objects: move tree_depth into 'struct packing_data', 2018-08-16) dynamically manages a tree_depth array in packing_data that maintains one of these invariants: 1. tree_depth is NULL (i.e., the requested options don't require us to track tree depths) 2. tree_depth is non-NULL and has as many entries as the "objects" array We maintain (2) by: a. When the objects array grows, grow tree_depth to the same size (unless it's NULL, in which case we can leave it). b. When a caller asks to set a depth via oe_set_tree_depth(), if tree_depth is NULL we allocate it. But in (b), we use the number of stored objects, _not_ the allocated size of the objects array. So we can run into a situation like this: 1. packlist_alloc() needs to store the Nth object, so it grows the objects array to M, where M > N. 2. oe_set_tree_depth() wants to store a depth, so it allocates an array of length N. Now we've violated our invariant. 3. packlist_alloc() needs to store the N+1th object. But it _doesn't_ grow the objects array, since N <= M still holds. We try to assign to tree_depth[N+1], which is out of bounds. That doesn't happen in our test scripts, because the repositories they use are so small, but it's easy to trigger by running: echo HEAD | git pack-objects --revs --delta-islands --stdout >/dev/null in any reasonably-sized repo (like git.git). We can fix it by always growing the array to match pack->nr_alloc, not pack->nr_objects. Likewise for the "layer" array from fe0ac2fb7f (pack-objects: move 'layer' into 'struct packing_data', 2018-08-16), which has the same bug. Signed-off-by: Jeff King --- pack-objects.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/pack-objects.h b/pack-objects.h index feb6a6a05e..f31ac1c81c 100644 --- a/pack-objects.h +++ b/pack-objects.h @@ -412,7 +412,7 @@ static inline void oe_set_tree_depth(struct packing_data *pack, unsigned int tree_depth) { if (!pack->tree_depth) - ALLOC_ARRAY(pack->tree_depth, pack->nr_objects); + ALLOC_ARRAY(pack->tree_depth, pack->nr_alloc); pack->tree_depth[e - pack->objects] = tree_depth; } @@ -429,7 +429,7 @@ static inline void oe_set_layer(struct packing_data *pack, unsigned char layer) { if (!pack->layer) - ALLOC_ARRAY(pack->layer, pack->nr_objects); + ALLOC_ARRAY(pack->layer, pack->nr_alloc); pack->layer[e - pack->objects] = layer; } -- 2.20.0.rc0.715.gf6b01ab3e1