From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeff King Subject: [PATCH] index-pack: fix truncation of off_t in comparison Date: Thu, 4 Jun 2015 08:35:42 -0400 Message-ID: <20150604123541.GA8888@peff.net> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Cc: Junio C Hamano , git@vger.kernel.org To: =?utf-8?B?Tmd1eeG7hW4gVGjDoWkgTmfhu41j?= Duy X-From: git-owner@vger.kernel.org Thu Jun 04 14:35:57 2015 Return-path: Envelope-to: gcvg-git-2@plane.gmane.org Received: from vger.kernel.org ([209.132.180.67]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1Z0UNC-0001Pj-Ou for gcvg-git-2@plane.gmane.org; Thu, 04 Jun 2015 14:35:51 +0200 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752896AbbFDMfq (ORCPT ); Thu, 4 Jun 2015 08:35:46 -0400 Received: from cloud.peff.net ([50.56.180.127]:41063 "HELO cloud.peff.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1751955AbbFDMfp (ORCPT ); Thu, 4 Jun 2015 08:35:45 -0400 Received: (qmail 28172 invoked by uid 102); 4 Jun 2015 12:35:45 -0000 Received: from Unknown (HELO peff.net) (10.0.1.1) by cloud.peff.net (qpsmtpd/0.84) with SMTP; Thu, 04 Jun 2015 07:35:45 -0500 Received: (qmail 31552 invoked by uid 107); 4 Jun 2015 12:35:46 -0000 Received: from sigill.intra.peff.net (HELO sigill.intra.peff.net) (10.0.0.7) by peff.net (qpsmtpd/0.84) with SMTP; Thu, 04 Jun 2015 08:35:46 -0400 Received: by sigill.intra.peff.net (sSMTP sendmail emulation); Thu, 04 Jun 2015 08:35:42 -0400 Content-Disposition: inline Sender: git-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org Archived-At: Commit c6458e6 (index-pack: kill union delta_base to save memory, 2015-04-18) refactored the comparison functions used in sorting and binary searching our delta list. The resulting code does something like: int cmp_offsets(off_t a, off_t b) { return a - b; } This works most of the time, but produces nonsensical results when the difference between the two offsets is larger than what can be stored in an "int". This can lead to unresolved deltas if the packsize is larger than 2G (even on 64-bit systems, an int is still typically 32 bits): $ git clone git://github.com/mozilla/gecko-dev Cloning into 'gecko-dev'... remote: Counting objects: 4800161, done. remote: Compressing objects: 100% (178/178), done. remote: Total 4800161 (delta 88), reused 0 (delta 0), pack-reused 4799978 Receiving objects: 100% (4800161/4800161), 2.21 GiB | 3.26 MiB/s, done. Resolving deltas: 99% (3808820/3811944), completed with 0 local objects. fatal: pack has 3124 unresolved deltas fatal: index-pack failed We can fix it by doing direct comparisons between the offsets and returning constants; the callers only care about the sign of the comparison, not the magnitude. Signed-off-by: Jeff King --- On top of nd/slim-index-pack-memory-usage, which introduced the bug (but it is already in master). builtin/index-pack.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/builtin/index-pack.c b/builtin/index-pack.c index 3ed53e3..06dd973 100644 --- a/builtin/index-pack.c +++ b/builtin/index-pack.c @@ -616,7 +616,9 @@ static int compare_ofs_delta_bases(off_t offset1, off_t offset2, int cmp = type1 - type2; if (cmp) return cmp; - return offset1 - offset2; + return offset1 < offset2 ? -1 : + offset1 > offset2 ? 1 : + 0; } static int find_ofs_delta(const off_t offset, enum object_type type) @@ -1051,7 +1053,9 @@ static int compare_ofs_delta_entry(const void *a, const void *b) const struct ofs_delta_entry *delta_a = a; const struct ofs_delta_entry *delta_b = b; - return delta_a->offset - delta_b->offset; + return delta_a->offset < delta_b->offset ? -1 : + delta_a->offset > delta_b->offset ? 1 : + 0; } static int compare_ref_delta_entry(const void *a, const void *b) -- 2.4.2.745.g0aa058d