Re: [PATCH] Avoid infinite loop in malformed packfiles

From: "René Scharfe" <l.s.r@web.de>
To: ori@eigenstate.org, gitster@pobox.com, peff@peff.net
Cc: git@vger.kernel.org
Subject: Re: [PATCH] Avoid infinite loop in malformed packfiles
Date: Sun, 30 Aug 2020 12:56:11 +0200	[thread overview]
Message-ID: <59efeeab-49de-17e7-8b1c-355d6ef31b5d@web.de> (raw)
In-Reply-To: <A1CA9D499EDDACBA275BA61E114645F0@eigenstate.org>

Am 30.08.20 um 05:33 schrieb ori@eigenstate.org:
>> Jeff King <peff@peff.net> writes:
>>
>>> It may be hard to test, as I suspect modern versions of Git are not
>>> happy to create such a deep chain. We could test with a lowered value of
>>> the config option, though.
>>
>> Yes, that was what I meant.  Start from a 1KB text, create 50
>> revisions of the file by adding a single line at its end at a time,
>> pack with depth limit of 100, and then see "git log -p" die when the
>> allowed max lowered to 10, or something like that.
>
> Sorry about the delay -- most of my time to poke at this is over the weekend.
>
> Will that work? I'd expect that modern pack files end up being
> offset deltas, rather than reference deltas.

True, but going down all the way would work:

diff --git a/t/t5316-pack-delta-depth.sh b/t/t5316-pack-delta-depth.sh
index 0f06c40eb1..7fd21cd3ce 100755
--- a/t/t5316-pack-delta-depth.sh
+++ b/t/t5316-pack-delta-depth.sh
@@ -94,4 +94,15 @@ test_expect_success '--depth limits depth' '
 	test_i18ncmp expect actual
 '

+test_expect_success 'maxAllowedDeltaDepth is respected' '
+	git clone . clone1 &&
+	(
+		cd clone1 &&
+		git repack -a -d &&
+		test_config core.maxAllowedDeltaDepth 0 &&
+		test_must_fail git fsck 2>err &&
+		test_i18ngrep "overlong delta chain" err
+	)
+'
+
 test_done


