From: Patrick Steinhardt <ps@pks.im>
To: Taylor Blau <me@ttaylorr.com>
Cc: git@vger.kernel.org, peff@peff.net, dstolee@microsoft.com
Subject: Re: [PATCH v2 1/8] midx: fix segfault with no packs and invalid preferred pack
Date: Thu, 13 Apr 2023 11:28:18 +0200 [thread overview]
Message-ID: <ZDfLMm-AoXkt-4zj@ncase> (raw)
In-Reply-To: <ZDbw6v8r89zciE3q@nand.local>
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On Wed, Apr 12, 2023 at 01:56:58PM -0400, Taylor Blau wrote:
> On Wed, Apr 12, 2023 at 12:22:31PM +0200, Patrick Steinhardt wrote:
> > Fix this bug by exiting early in case we have determined that the MIDX
> > wouldn't have any packfiles to index. While the request itself does not
> > make much sense anyway, it is still preferable to exit gracefully than
> > to abort.
>
> Interesting. This reminded me quite a bit of eb57277ba3 (midx: prevent
> writing a .bitmap without any objects, 2022-02-09) which tackled a
> similar problem of trying to write a MIDX bitmap without any objects.
>
> We may want to consider moving that conditional further up, since this
> makes the conditional added in eb57277ba3 dead code AFAICT. Here's a
> patch on top of this one that I think would do the trick.
>
> It has the added benefit of sticking a:
>
> warning: unknown preferred pack: 'does-not-exist'
>
> in the output before dying, which might be nice (though I doubt anybody
> will ever see it ;-)). The main difference is that we unset the bitmap
> related bits from `flags`, which avoids us trying to compute a preferred
> pack in the first place.
>
> For it to work, though, we need to make sure that ctx.preferred_pack_idx
> is set to -1, and not zero-initialized, since we'll segfault otherwise
> when trying to read into an empty array.
Indeed, that is a good point. I think we can simplify your patch even
further in that case:
diff --git a/midx.c b/midx.c
index 47989f7ea7..67eb617591 100644
--- a/midx.c
+++ b/midx.c
@@ -1328,17 +1328,17 @@ static int write_midx_internal(const char *object_dir,
}
if (preferred_pack_name) {
- int found = 0;
+ ctx.preferred_pack_idx = -1;
+
for (i = 0; i < ctx.nr; i++) {
if (!cmp_idx_or_pack_name(preferred_pack_name,
ctx.info[i].pack_name)) {
ctx.preferred_pack_idx = i;
- found = 1;
break;
}
}
- if (!found)
+ if (ctx.preferred_pack_idx == -1)
warning(_("unknown preferred pack: '%s'"),
preferred_pack_name);
} else if (ctx.nr &&
The other cases already set `preferred_pack_idx = -1`, so this is really
all we need to do to fix the segfault.
Patrick
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next prev parent reply other threads:[~2023-04-13 9:28 UTC|newest]
Thread overview: 67+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-04-04 11:08 [PATCH] repack: fix geometric repacking with gitalternates Patrick Steinhardt
2023-04-04 18:55 ` Taylor Blau
2023-04-04 19:00 ` Taylor Blau
2023-04-05 7:08 ` Patrick Steinhardt
2023-04-10 15:06 ` Derrick Stolee
2023-04-10 23:49 ` Taylor Blau
2023-04-11 17:13 ` Patrick Steinhardt
2023-04-11 21:13 ` Taylor Blau
2023-04-12 9:37 ` Patrick Steinhardt
2023-04-11 17:06 ` Patrick Steinhardt
2023-04-11 17:26 ` Patrick Steinhardt
2023-04-11 21:14 ` Taylor Blau
2023-04-10 23:29 ` Taylor Blau
2023-04-12 10:22 ` [PATCH v2 0/8] " Patrick Steinhardt
2023-04-12 10:22 ` [PATCH v2 1/8] midx: fix segfault with no packs and invalid preferred pack Patrick Steinhardt
2023-04-12 17:56 ` Taylor Blau
2023-04-13 9:28 ` Patrick Steinhardt [this message]
2023-04-12 10:22 ` [PATCH v2 2/8] repack: fix trying to use preferred pack in alternates Patrick Steinhardt
2023-04-12 18:37 ` Taylor Blau
2023-04-13 9:31 ` Patrick Steinhardt
2023-04-12 10:22 ` [PATCH v2 3/8] repack: fix generating multi-pack-index with only non-local packs Patrick Steinhardt
2023-04-12 20:39 ` Taylor Blau
2023-04-12 10:22 ` [PATCH v2 4/8] pack-objects: fix error when packing same pack twice Patrick Steinhardt
2023-04-12 21:33 ` Taylor Blau
2023-04-12 10:22 ` [PATCH v2 5/8] pack-objects: fix error when same packfile is included and excluded Patrick Steinhardt
2023-04-12 21:52 ` Taylor Blau
2023-04-12 10:22 ` [PATCH v2 6/8] pack-objects: extend test coverage of `--stdin-packs` with alternates Patrick Steinhardt
2023-04-12 10:22 ` [PATCH v2 7/8] repack: honor `-l` when calculating pack geometry Patrick Steinhardt
2023-04-12 23:56 ` Junio C Hamano
2023-04-13 5:11 ` Junio C Hamano
2023-04-13 6:41 ` Patrick Steinhardt
2023-04-12 10:23 ` [PATCH v2 8/8] repack: disable writing bitmaps when doing a local geometric repack Patrick Steinhardt
2023-04-12 22:01 ` Taylor Blau
2023-04-13 9:54 ` Patrick Steinhardt
2023-04-13 10:14 ` Patrick Steinhardt
2023-04-12 22:02 ` [PATCH v2 0/8] repack: fix geometric repacking with gitalternates Taylor Blau
2023-04-13 11:16 ` [PATCH v3 00/10] " Patrick Steinhardt
2023-04-13 11:16 ` [PATCH v3 01/10] midx: fix segfault with no packs and invalid preferred pack Patrick Steinhardt
2023-04-13 13:49 ` Derrick Stolee
2023-04-13 11:16 ` [PATCH v3 02/10] repack: fix trying to use preferred pack in alternates Patrick Steinhardt
2023-04-13 11:16 ` [PATCH v3 03/10] repack: fix generating multi-pack-index with only non-local packs Patrick Steinhardt
2023-04-13 11:16 ` [PATCH v3 04/10] pack-objects: split out `--stdin-packs` tests into separate file Patrick Steinhardt
2023-04-13 11:16 ` [PATCH v3 05/10] pack-objects: fix error when packing same pack twice Patrick Steinhardt
2023-04-13 11:16 ` [PATCH v3 06/10] pack-objects: fix error when same packfile is included and excluded Patrick Steinhardt
2023-04-13 11:16 ` [PATCH v3 07/10] pack-objects: extend test coverage of `--stdin-packs` with alternates Patrick Steinhardt
2023-04-13 11:16 ` [PATCH v3 08/10] t/helper: allow chmtime to print verbosely without modifying mtime Patrick Steinhardt
2023-04-13 11:16 ` [PATCH v3 09/10] repack: honor `-l` when calculating pack geometry Patrick Steinhardt
2023-04-13 13:59 ` Derrick Stolee
2023-04-13 14:13 ` Patrick Steinhardt
2023-04-13 15:40 ` Junio C Hamano
2023-04-13 11:16 ` [PATCH v3 10/10] repack: disable writing bitmaps when doing a local repack Patrick Steinhardt
2023-04-13 14:54 ` [PATCH v3 00/10] repack: fix geometric repacking with gitalternates Derrick Stolee
2023-04-14 2:03 ` Junio C Hamano
2023-04-14 5:42 ` Patrick Steinhardt
2023-04-14 6:01 ` [PATCH v4 " Patrick Steinhardt
2023-04-14 6:01 ` [PATCH v4 01/10] midx: fix segfault with no packs and invalid preferred pack Patrick Steinhardt
2023-04-14 6:01 ` [PATCH v4 02/10] repack: fix trying to use preferred pack in alternates Patrick Steinhardt
2023-04-14 6:01 ` [PATCH v4 03/10] repack: fix generating multi-pack-index with only non-local packs Patrick Steinhardt
2023-04-14 6:01 ` [PATCH v4 04/10] pack-objects: split out `--stdin-packs` tests into separate file Patrick Steinhardt
2023-04-14 6:01 ` [PATCH v4 05/10] pack-objects: fix error when packing same pack twice Patrick Steinhardt
2023-04-14 6:01 ` [PATCH v4 06/10] pack-objects: fix error when same packfile is included and excluded Patrick Steinhardt
2023-04-14 6:01 ` [PATCH v4 07/10] pack-objects: extend test coverage of `--stdin-packs` with alternates Patrick Steinhardt
2023-04-14 6:02 ` [PATCH v4 08/10] t/helper: allow chmtime to print verbosely without modifying mtime Patrick Steinhardt
2023-04-14 6:02 ` [PATCH v4 09/10] repack: honor `-l` when calculating pack geometry Patrick Steinhardt
2023-04-14 6:02 ` [PATCH v4 10/10] repack: disable writing bitmaps when doing a local repack Patrick Steinhardt
2023-04-14 13:23 ` [PATCH v4 00/10] repack: fix geometric repacking with gitalternates Derrick Stolee
2023-04-14 17:29 ` Junio C Hamano
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