From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9E2F2CD6139 for ; Mon, 9 Oct 2023 21:05:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1378604AbjJIVFh (ORCPT ); Mon, 9 Oct 2023 17:05:37 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46286 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1378221AbjJIVFf (ORCPT ); Mon, 9 Oct 2023 17:05:35 -0400 Received: from cloud.peff.net (cloud.peff.net [104.130.231.41]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0A5EFA9 for ; Mon, 9 Oct 2023 14:05:31 -0700 (PDT) Received: (qmail 24392 invoked by uid 109); 9 Oct 2023 21:05:31 -0000 Received: from Unknown (HELO peff.net) (10.0.1.2) by cloud.peff.net (qpsmtpd/0.94) with ESMTP; Mon, 09 Oct 2023 21:05:31 +0000 Authentication-Results: cloud.peff.net; auth=none Received: (qmail 18598 invoked by uid 111); 9 Oct 2023 21:05:33 -0000 Received: from coredump.intra.peff.net (HELO coredump.intra.peff.net) (10.0.0.2) by peff.net (qpsmtpd/0.94) with (TLS_AES_256_GCM_SHA384 encrypted) ESMTPS; Mon, 09 Oct 2023 17:05:33 -0400 Authentication-Results: peff.net; auth=none Date: Mon, 9 Oct 2023 17:05:30 -0400 From: Jeff King To: git@vger.kernel.org Cc: Taylor Blau Subject: [PATCH 10/20] midx: bounds-check large offset chunk Message-ID: <20231009210530.GJ3282181@coredump.intra.peff.net> References: <20231009205544.GA3281950@coredump.intra.peff.net> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20231009205544.GA3281950@coredump.intra.peff.net> Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org When we see a large offset bit in the regular midx offset table, we use the entry as an index into a separate large offset table (just like a pack idx does). But we don't bounds-check the access to that large offset table (nor even record its size when we parse the chunk!). The equivalent code for a regular pack idx is in check_pack_index_ptr(). But things are a bit simpler here because of the chunked format: we can just check our array index directly. As a bonus, we can get rid of the st_mult() here. If our array bounds-check is successful, then we know that the result will fit in a size_t (and the bounds check uses a division to avoid overflow entirely). Signed-off-by: Jeff King --- midx.c | 8 +++++--- midx.h | 1 + t/t5319-multi-pack-index.sh | 20 ++++++++++++++++++++ 3 files changed, 26 insertions(+), 3 deletions(-) diff --git a/midx.c b/midx.c index 7b1b45f381..3e768d0df0 100644 --- a/midx.c +++ b/midx.c @@ -180,7 +180,8 @@ struct multi_pack_index *load_multi_pack_index(const char *object_dir, int local if (read_chunk(cf, MIDX_CHUNKID_OBJECTOFFSETS, midx_read_object_offsets, m)) die(_("multi-pack-index required object offsets chunk missing or corrupted")); - pair_chunk_unsafe(cf, MIDX_CHUNKID_LARGEOFFSETS, &m->chunk_large_offsets); + pair_chunk(cf, MIDX_CHUNKID_LARGEOFFSETS, &m->chunk_large_offsets, + &m->chunk_large_offsets_len); if (git_env_bool("GIT_TEST_MIDX_READ_RIDX", 1)) pair_chunk_unsafe(cf, MIDX_CHUNKID_REVINDEX, &m->chunk_revindex); @@ -303,8 +304,9 @@ off_t nth_midxed_offset(struct multi_pack_index *m, uint32_t pos) die(_("multi-pack-index stores a 64-bit offset, but off_t is too small")); offset32 ^= MIDX_LARGE_OFFSET_NEEDED; - return get_be64(m->chunk_large_offsets + - st_mult(sizeof(uint64_t), offset32)); + if (offset32 >= m->chunk_large_offsets_len / sizeof(uint64_t)) + die(_("multi-pack-index large offset out of bounds")); + return get_be64(m->chunk_large_offsets + sizeof(uint64_t) * offset32); } return offset32; diff --git a/midx.h b/midx.h index 5b2a7da043..e8e8884d16 100644 --- a/midx.h +++ b/midx.h @@ -37,6 +37,7 @@ struct multi_pack_index { const unsigned char *chunk_oid_lookup; const unsigned char *chunk_object_offsets; const unsigned char *chunk_large_offsets; + size_t chunk_large_offsets_len; const unsigned char *chunk_revindex; const char **pack_names; diff --git a/t/t5319-multi-pack-index.sh b/t/t5319-multi-pack-index.sh index 30687d5452..16050f39d9 100755 --- a/t/t5319-multi-pack-index.sh +++ b/t/t5319-multi-pack-index.sh @@ -1118,4 +1118,24 @@ test_expect_success 'reader notices too-small object offset chunk' ' test_cmp expect err ' +test_expect_success 'reader bounds-checks large offset table' ' + # re-use the objects64 dir here to cheaply get access to a midx + # with large offsets. + git init repo && + test_when_finished "rm -rf repo" && + ( + cd repo && + (cd ../objects64 && pwd) >.git/objects/info/alternates && + git multi-pack-index --object-dir=../objects64 write && + midx=../objects64/pack/multi-pack-index && + corrupt_chunk_file $midx LOFF clear && + test_must_fail git cat-file \ + --batch-check --batch-all-objects 2>err && + cat >expect <<-\EOF && + fatal: multi-pack-index large offset out of bounds + EOF + test_cmp expect err + ) +' + test_done -- 2.42.0.884.g35e1fe1a6a