From: Jeff King <peff@peff.net>
To: Junio C Hamano <gitster@pobox.com>
Cc: "Ævar Arnfjörð Bjarmason" <avarab@gmail.com>,
"Git Mailing List" <git@vger.kernel.org>,
"John Szakmeister" <john@szakmeister.net>,
"Dennis Kaarsemaker" <dennis@kaarsemaker.net>
Subject: Re: Infinite loop regression in git-fsck in v2.12.0
Date: Tue, 30 Oct 2018 18:56:03 -0400 [thread overview]
Message-ID: <20181030225603.GA5889@sigill.intra.peff.net> (raw)
In-Reply-To: <xmqq4ld3134f.fsf@gitster-ct.c.googlers.com>
On Wed, Oct 31, 2018 at 07:28:00AM +0900, Junio C Hamano wrote:
> > So we need to distinguish those cases. I think this is the simplest fix:
> >
> > diff --git a/sha1-file.c b/sha1-file.c
> > index dd0b6aa873..a7ff5fe25d 100644
> > --- a/sha1-file.c
> > +++ b/sha1-file.c
> > @@ -2199,6 +2199,7 @@ static int check_stream_sha1(git_zstream *stream,
> > * see the comment in unpack_sha1_rest for details.
> > */
> > while (total_read <= size &&
> > + stream->avail_in > 0 &&
> > (status == Z_OK || status == Z_BUF_ERROR)) {
> > stream->next_out = buf;
> > stream->avail_out = sizeof(buf);
>
> Hmph. If the last round consumed the final input byte and needed
> output space of N bytes, but only M (< N) bytes of the output space
> was available, then it would have reduced both avail_in and
> avail_out down to zero and yielded Z_BUF_ERROR, no? Or would zlib
> refrain from consuming that final byte (leaving avail_in to at least
> one) and give us Z_BUF_ERROR in such a case?
Hmm, yeah, good thinking. I think zlib could consume that final byte
into its internal buffer.
As part of my digging, I looked at how the loose streaming code handles
this. It checks that when we see Z_BUF_ERROR, we actually did run out of
output bytes (so if we didn't, then we know it's not the case we
expected to be looping on).
I have some patches almost ready to send; I'll use that technique.
-Peff
next prev parent reply other threads:[~2018-10-30 22:56 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-01-07 12:50 "git fsck" not detecting garbage at the end of blob object files John Szakmeister
2017-01-07 21:47 ` Dennis Kaarsemaker
2017-01-08 5:26 ` Jeff King
2017-01-13 9:15 ` John Szakmeister
2017-01-13 17:52 ` [PATCH 0/6] loose-object fsck fixes/tightening Jeff King
2017-01-13 17:54 ` [PATCH 1/6] t1450: refactor loose-object removal Jeff King
2017-01-13 17:54 ` [PATCH 2/6] sha1_file: fix error message for alternate objects Jeff King
2017-01-13 17:55 ` [PATCH 3/6] t1450: test fsck of packed objects Jeff King
2017-01-13 17:58 ` [PATCH 4/6] sha1_file: add read_loose_object() function Jeff King
2017-01-13 17:59 ` [PATCH 5/6] fsck: parse loose object paths directly Jeff King
2018-10-30 20:03 ` Infinite loop regression in git-fsck in v2.12.0 Ævar Arnfjörð Bjarmason
2018-10-30 21:35 ` Jeff King
2018-10-30 22:28 ` Junio C Hamano
2018-10-30 22:56 ` Jeff King [this message]
2018-10-30 23:12 ` Jeff King
2018-10-30 23:18 ` [PATCH 1/3] t1450: check large blob in trailing-garbage test Jeff King
2018-10-30 23:23 ` [PATCH 2/3] check_stream_sha1(): handle input underflow Jeff King
2018-10-31 4:23 ` Junio C Hamano
2018-10-31 4:30 ` Jeff King
2018-10-31 4:44 ` Junio C Hamano
2018-10-31 5:03 ` Jeff King
2018-10-31 5:13 ` Jeff King
2018-10-31 5:31 ` Junio C Hamano
2018-10-30 23:23 ` [PATCH 3/3] cat-file: handle streaming failures consistently Jeff King
2018-10-31 12:42 ` [PATCH 0/3] Add a GIT_TEST_FSCK test mode Ævar Arnfjörð Bjarmason
2018-10-31 12:42 ` [PATCH 1/3] tests: add a "env-bool" helper to test-tool Ævar Arnfjörð Bjarmason
2018-10-31 12:42 ` [PATCH 2/3] tests: mark those tests where "git fsck" fails at the end Ævar Arnfjörð Bjarmason
2018-11-01 3:37 ` Junio C Hamano
2018-10-31 12:42 ` [PATCH 3/3] tests: add a special test setup that runs "git fsck" before exiting Ævar Arnfjörð Bjarmason
2018-10-31 13:33 ` [PATCH 3/3] cat-file: handle streaming failures consistently Torsten Bögershausen
2018-10-31 14:23 ` Junio C Hamano
2018-10-31 14:37 ` Jeff King
2018-10-31 17:38 ` Eric Sunshine
2018-10-31 20:29 ` Jeff King
2018-10-30 21:56 ` Infinite loop regression in git-fsck in v2.12.0 Ævar Arnfjörð Bjarmason
2018-10-30 23:08 ` Jeff King
2017-01-13 18:00 ` [PATCH 6/6] fsck: detect trailing garbage in all object types Jeff King
2017-01-19 11:18 ` [PATCH 0/6] loose-object fsck fixes/tightening John Szakmeister
2017-01-13 9:16 ` "git fsck" not detecting garbage at the end of blob object files John Szakmeister
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