From: Jeff King <peff@peff.net>
To: Taylor Blau <me@ttaylorr.com>
Cc: git@vger.kernel.org
Subject: Re: [PATCH 12/20] commit-graph: check size of commit data chunk
Date: Wed, 11 Oct 2023 19:22:17 -0400 [thread overview]
Message-ID: <20231011232217.GL518221@coredump.intra.peff.net> (raw)
In-Reply-To: <ZSbthK5919QdrEPx@nand.local>
On Wed, Oct 11, 2023 at 02:46:28PM -0400, Taylor Blau wrote:
> > +static int graph_read_commit_data(const unsigned char *chunk_start,
> > + size_t chunk_size, void *data)
> > +{
> > + struct commit_graph *g = data;
> > + if (chunk_size != g->num_commits * GRAPH_DATA_WIDTH)
>
> Should this be guarded with an st_mult? I think that GRAPH_DATA_WIDTH is
> defined as (the_hash_algo->rawsz + 16), so I *think* that the expression
> in the parenthesis would get done as a size_t, and then g->num_commits
> would be widened to a size_t for the purposes of evaluating this
> expression.
>
> So I think that this is all OK in the sense that we'd never underflow
> the 64-bit space, and having more than 2^64-1/36 (some eighteen
> quintillion) commits is... unlikely ;-).
Hmm, yeah, I think you are right, but I agree it's awfully subtle. There
is no reason somebody couldn't later change "rawsz" to a smaller type
(after all, we know it's going to be tiny), and it would be quite
surprising if that introduces an overflow in far-away code. We should
protect ourselves here.
-Peff
next prev parent reply other threads:[~2023-10-11 23:22 UTC|newest]
Thread overview: 67+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-10-09 20:55 [PATCH 0/20] bounds-checks for chunk-based files Jeff King
2023-10-09 20:58 ` [PATCH 01/20] chunk-format: note that pair_chunk() is unsafe Jeff King
2023-10-10 23:45 ` Taylor Blau
2023-10-11 22:49 ` Jeff King
2023-10-09 20:58 ` [PATCH 02/20] t: add library for munging chunk-format files Jeff King
2023-10-10 23:47 ` Taylor Blau
2023-10-09 20:59 ` [PATCH 03/20] midx: stop ignoring malformed oid fanout chunk Jeff King
2023-10-10 23:50 ` Taylor Blau
2023-10-11 22:52 ` Jeff King
2023-10-09 20:59 ` [PATCH 04/20] commit-graph: check size of " Jeff King
2023-10-11 0:08 ` Taylor Blau
2023-10-11 1:24 ` Taylor Blau
2023-10-11 23:01 ` Jeff King
2023-10-09 21:02 ` [PATCH 05/20] midx: check size of oid lookup chunk Jeff King
2023-10-09 21:04 ` [PATCH 06/20] commit-graph: check consistency of fanout table Jeff King
2023-10-11 14:45 ` Taylor Blau
2023-10-09 21:05 ` [PATCH 07/20] midx: check size of pack names chunk Jeff King
2023-10-11 14:52 ` Taylor Blau
2023-10-11 23:06 ` Jeff King
2023-10-09 21:05 ` [PATCH 08/20] midx: enforce chunk alignment on reading Jeff King
2023-10-11 14:56 ` Taylor Blau
2023-10-11 15:01 ` Taylor Blau
2023-10-11 23:09 ` Jeff King
2023-10-09 21:05 ` [PATCH 09/20] midx: check size of object offset chunk Jeff King
2023-10-11 18:31 ` Taylor Blau
2023-10-09 21:05 ` [PATCH 10/20] midx: bounds-check large " Jeff King
2023-10-11 18:38 ` Taylor Blau
2023-10-11 23:18 ` Jeff King
2023-10-09 21:05 ` [PATCH 11/20] midx: check size of revindex chunk Jeff King
2023-10-11 18:41 ` Taylor Blau
2023-10-09 21:05 ` [PATCH 12/20] commit-graph: check size of commit data chunk Jeff King
2023-10-11 18:46 ` Taylor Blau
2023-10-11 23:22 ` Jeff King [this message]
2023-10-09 21:05 ` [PATCH 13/20] commit-graph: detect out-of-bounds extra-edges pointers Jeff King
2023-10-11 19:02 ` Taylor Blau
2023-10-09 21:05 ` [PATCH 14/20] commit-graph: bounds-check base graphs chunk Jeff King
2023-10-11 19:05 ` Taylor Blau
2023-10-09 21:05 ` [PATCH 15/20] commit-graph: check size of generations chunk Jeff King
2023-10-09 21:05 ` [PATCH 16/20] commit-graph: bounds-check generation overflow chunk Jeff King
2023-10-09 21:05 ` [PATCH 17/20] commit-graph: check bounds when accessing BDAT chunk Jeff King
2023-10-11 19:11 ` Taylor Blau
2023-10-11 23:27 ` Jeff King
2023-10-09 21:05 ` [PATCH 18/20] commit-graph: check bounds when accessing BIDX chunk Jeff King
2023-10-11 19:15 ` Taylor Blau
2023-10-09 21:05 ` [PATCH 19/20] commit-graph: detect out-of-order BIDX offsets Jeff King
2023-10-11 19:16 ` Taylor Blau
2023-10-09 21:06 ` [PATCH 20/20] chunk-format: drop pair_chunk_unsafe() Jeff King
2023-10-11 19:19 ` [PATCH 0/20] bounds-checks for chunk-based files Taylor Blau
2023-10-11 23:31 ` Jeff King
2023-10-13 19:25 ` [PATCH 0/8] chunk-format: introduce `pair_chunk_expect()` convenience API Taylor Blau
2023-10-13 19:25 ` [PATCH 1/8] chunk-format: introduce `pair_chunk_expect()` helper Taylor Blau
2023-10-13 19:25 ` [PATCH 2/8] commit-graph: read `OIDF` chunk with `pair_chunk_expect()` Taylor Blau
2023-10-13 19:25 ` [PATCH 3/8] commit-graph: read `CDAT` " Taylor Blau
2023-10-13 19:25 ` [PATCH 4/8] commit-graph: read `GDAT` " Taylor Blau
2023-10-13 19:25 ` [PATCH 5/8] commit-graph: read `BIDX` " Taylor Blau
2023-10-13 19:49 ` Taylor Blau
2023-10-14 16:10 ` Junio C Hamano
2023-10-20 10:31 ` Jeff King
2023-10-13 19:25 ` [PATCH 6/8] midx: read `OIDF` " Taylor Blau
2023-10-13 21:04 ` Junio C Hamano
2023-10-13 19:25 ` [PATCH 7/8] midx: read `OIDL` " Taylor Blau
2023-10-13 19:25 ` [PATCH 8/8] midx: read `OOFF` " Taylor Blau
2023-10-20 10:23 ` [PATCH 0/8] chunk-format: introduce `pair_chunk_expect()` convenience API Jeff King
2023-10-14 0:43 ` [PATCH 21/20] t5319: make corrupted large-offset test more robust Jeff King
2023-10-14 19:42 ` Junio C Hamano
2023-10-15 3:17 ` Jeff King
2023-10-15 17:04 ` Junio C Hamano
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