From: Anders Waldenborg <anders@0x63.nu>
To: Junio C Hamano <gitster@pobox.com>
Cc: git@vger.kernel.org, Jeff King <peff@peff.net>,
Olga Telezhnaya <olyatelezhnaya@gmail.com>
Subject: Re: [PATCH v2 5/5] pretty: add support for separator option in %(trailers)
Date: Mon, 05 Nov 2018 19:24:14 +0100 [thread overview]
Message-ID: <871s7zl6xp.fsf@0x63.nu> (raw)
In-Reply-To: <xmqqpnvkjmtu.fsf@gitster-ct.c.googlers.com>
Junio C Hamano writes:
> Anders Waldenborg <anders@0x63.nu> writes:
>
>> @@ -1352,6 +1353,17 @@ static size_t format_commit_one(struct strbuf *sb, /* in UTF-8 */
>> arg++;
>>
>> opts.only_trailers = 1;
>> + } else if (skip_prefix(arg, "separator=", &arg)) {
>> + size_t seplen = strcspn(arg, ",)");
>> + strbuf_reset(&sepbuf);
>> + char *fmt = xstrndup(arg, seplen);
>> + strbuf_expand(&sepbuf, fmt, format_fundamental, NULL);
>
> This somehow feels akin to using end-user supplied param to printf(3)
> as its format argument e.g.
>
> int main(int ac, char *av) {
> printf(av[1]);
> return 0;
> }
>
> which is not a good idea. Is there a mechanism with which we can
> ensure that the separator=<what> specification will never come from
> potentially malicious sources (e.g. not used to show things on webpage
> allowing random folks who access he site to supply custom format)?
I can't see a case where this could add anything that isn't already
possible.
AFAICU strbuf_expand doesn't suffer from the worst things that printf(3)
suffers from wrt untrusted format string (i.e no printf style %n which
can write to memory, and no vaargs on stack which allows leaking random
stuff).
The separator option is part of the full format string. If a malicious
user can specify that, they can't really do anything new, as the
separator only can expand %n and %xNN, which they already can do in the
full string.
But maybe I'm missing something?
next prev parent reply other threads:[~2018-11-05 18:24 UTC|newest]
Thread overview: 69+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-28 12:50 [PATCH] pretty: Add %(trailer:X) to display single trailer Anders Waldenborg
2018-10-29 4:49 ` Junio C Hamano
2018-10-29 14:14 ` Jeff King
2018-10-29 17:05 ` Anders Waldenborg
2018-10-31 20:27 ` Jeff King
2018-10-31 23:01 ` Anders Waldenborg
2018-11-01 18:42 ` Jeff King
2018-11-04 15:22 ` [PATCH v2 0/5] %(trailers) improvements in pretty format Anders Waldenborg
2018-11-04 15:22 ` [PATCH v2 1/5] pretty: single return path in %(trailers) handling Anders Waldenborg
2018-11-04 15:22 ` [PATCH v2 2/5] pretty: allow showing specific trailers Anders Waldenborg
2018-11-04 18:14 ` Eric Sunshine
2018-11-05 3:48 ` Junio C Hamano
2018-11-05 3:52 ` Eric Sunshine
2018-11-05 8:26 ` Anders Waldenborg
2018-11-05 9:00 ` Eric Sunshine
2018-11-05 5:14 ` Junio C Hamano
2018-11-04 15:22 ` [PATCH v2 3/5] pretty: add support for "nokey" option in %(trailers) Anders Waldenborg
2018-11-04 15:22 ` [PATCH v2 4/5] pretty: extract fundamental placeholders to separate function Anders Waldenborg
2018-11-05 2:06 ` Junio C Hamano
2018-11-05 8:32 ` Anders Waldenborg
2018-11-06 1:46 ` Junio C Hamano
2018-11-04 15:22 ` [PATCH v2 5/5] pretty: add support for separator option in %(trailers) Anders Waldenborg
2018-11-05 2:10 ` Junio C Hamano
2018-11-05 18:24 ` Anders Waldenborg [this message]
2018-11-06 1:48 ` Junio C Hamano
2018-11-05 5:18 ` Junio C Hamano
2018-11-04 17:40 ` [PATCH v2 0/5] %(trailers) improvements in pretty format Eric Sunshine
2018-11-05 7:09 ` Anders Waldenborg
2018-11-18 11:44 ` [PATCH v3 " Anders Waldenborg
2018-11-18 11:44 ` [PATCH v3 1/5] pretty: single return path in %(trailers) handling Anders Waldenborg
2018-11-18 11:44 ` [PATCH v3 2/5] pretty: allow showing specific trailers Anders Waldenborg
2018-11-20 5:45 ` Junio C Hamano
2018-11-20 5:59 ` Junio C Hamano
2018-11-25 23:02 ` Anders Waldenborg
2018-11-26 3:13 ` Junio C Hamano
2018-11-26 6:56 ` Anders Waldenborg
2018-11-26 7:52 ` Junio C Hamano
2018-11-18 11:44 ` [PATCH v3 3/5] pretty: add support for "valueonly" option in %(trailers) Anders Waldenborg
2018-11-20 8:14 ` Eric Sunshine
2018-11-18 11:44 ` [PATCH v3 4/5] strbuf: separate callback for strbuf_expand:ing literals Anders Waldenborg
2018-11-18 11:44 ` [PATCH v3 5/5] pretty: add support for separator option in %(trailers) Anders Waldenborg
2018-11-20 8:25 ` Eric Sunshine
2018-12-08 16:36 ` [PATCH v4 0/7] %(trailers) improvements in pretty format Anders Waldenborg
2018-12-08 16:36 ` [PATCH v4 1/7] doc: group pretty-format.txt placeholders descriptions Anders Waldenborg
2018-12-08 16:36 ` [PATCH v4 2/7] pretty: allow %(trailers) options with explicit value Anders Waldenborg
2018-12-10 8:45 ` Junio C Hamano
2018-12-18 21:30 ` Anders Waldenborg
2019-01-29 16:55 ` Jeff King
2019-01-29 21:23 ` Anders Waldenborg
[not found] ` <CAL21Bmmx=EO+R2t+KviNekDhU3fc0wjCcmUmbzLa14bb0PAmHA@mail.gmail.com>
2019-01-31 18:46 ` Anders Waldenborg
2019-02-02 9:14 ` Оля Тележная
2018-12-08 16:36 ` [PATCH v4 3/7] pretty: single return path in %(trailers) handling Anders Waldenborg
2018-12-08 16:36 ` [PATCH v4 4/7] pretty: allow showing specific trailers Anders Waldenborg
2018-12-10 8:56 ` Junio C Hamano
2018-12-08 16:36 ` [PATCH v4 5/7] pretty: add support for "valueonly" option in %(trailers) Anders Waldenborg
2018-12-08 16:36 ` [PATCH v4 6/7] strbuf: separate callback for strbuf_expand:ing literals Anders Waldenborg
2018-12-08 16:36 ` [PATCH v4 7/7] pretty: add support for separator option in %(trailers) Anders Waldenborg
2019-01-28 21:33 ` [PATCH v5 0/7] %(trailers) improvements in pretty format Anders Waldenborg
2019-01-28 21:33 ` [PATCH v5 1/7] doc: group pretty-format.txt placeholders descriptions Anders Waldenborg
2019-01-28 21:33 ` [PATCH v5 2/7] pretty: Allow %(trailers) options with explicit value Anders Waldenborg
2019-01-28 22:38 ` Junio C Hamano
2019-01-29 6:45 ` Anders Waldenborg
2019-01-29 16:57 ` Jeff King
2019-01-29 6:49 ` [PATCH v5 2/7 update] pretty: allow " Anders Waldenborg
2019-01-28 21:33 ` [PATCH v5 3/7] pretty: single return path in %(trailers) handling Anders Waldenborg
2019-01-28 21:33 ` [PATCH v5 4/7] pretty: allow showing specific trailers Anders Waldenborg
2019-01-28 21:33 ` [PATCH v5 5/7] pretty: add support for "valueonly" option in %(trailers) Anders Waldenborg
2019-01-28 21:33 ` [PATCH v5 6/7] strbuf: separate callback for strbuf_expand:ing literals Anders Waldenborg
2019-01-28 21:33 ` [PATCH v5 7/7] pretty: add support for separator option in %(trailers) Anders Waldenborg
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