git@vger.kernel.org mailing list mirror (one of many)
 help / color / mirror / code / Atom feed
From: Junio C Hamano <gitster@pobox.com>
To: Andrzej Hunt <andrzej@ahunt.org>
Cc: Miriam Rubio <mirucam@gmail.com>,
	git@vger.kernel.org, Tanushree Tumane <tanushreetumane@gmail.com>,
	Christian Couder <chriscool@tuxfamily.org>
Subject: Re: [PATCH v3 3/4] bisect--helper: reimplement `bisect_run` shell function in C
Date: Wed, 05 May 2021 11:04:04 +0900	[thread overview]
Message-ID: <xmqqzgxa3pij.fsf@gitster.g> (raw)
In-Reply-To: <3771bfc2-e4a4-3c5d-bcf5-673b403358ca@ahunt.org> (Andrzej Hunt's message of "Tue, 4 May 2021 19:26:01 +0200")

Andrzej Hunt <andrzej@ahunt.org> writes:

>> +	struct strbuf command = STRBUF_INIT;
>> +	struct strvec args = STRVEC_INIT;
>> +	struct strvec run_args = STRVEC_INIT;
>> + ...
>> +	run_args.v[0] = xstrdup(command.buf);
>> +	run_args.nr = 1;
>
> AFAIUI manipulating the strvec directly like this means that we will
> violate the promise that strvec.v is always NULL-terminated. It's 
> probably safer to call 'strvec_push(run_args, command.buf)' instead of
> manipulating v and nr?

True.

> Violating the NULL-termination promise a problem because... (continued
> below)
>
>> +
>> +	while (1) {
>> +		strvec_clear(&args);
>> +		exit = 1;
>> +
>> +		printf(_("running %s"), command.buf);
>> +		res = run_command_v_opt(run_args.v, RUN_USING_SHELL);
>
> run_command_v_opt() implicitly expects a NULL-terminated list of
> strings. It's not documented in run_command_v_opt()'s comments,
> however run_command_v_opt() does explain that it's a wrapper around 
> start_command(), which uses child_process, and child_process.argv is
> documented to require a NULL-terminated list.
>
> If argv is not NULL-terminated, we hit a buffer overflow read  in
> prepare_shell_cmd(), which can be reproduced by running something
> like:
>
>   make CC=clang-11 SANITIZE=address COPTS="-Og -g" GIT_TEST_OPTS=-v
>   T=t6030-bisect-porcelain.sh test
>
> which results in ASAN reporting this error:
> ...

Thanks for a careful explanation.


  reply	other threads:[~2021-05-05  2:04 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-11  9:55 [PATCH v3 0/4] Finish converting git bisect to C part 4 Miriam Rubio
2021-04-11  9:55 ` [PATCH v3 1/4] run-command: make `exists_in_PATH()` non-static Miriam Rubio
2021-04-11  9:55 ` [PATCH v3 2/4] bisect--helper: reimplement `bisect_visualize()`shell function in C Miriam Rubio
2021-04-11 20:22   ` Junio C Hamano
2021-04-11  9:55 ` [PATCH v3 3/4] bisect--helper: reimplement `bisect_run` shell " Miriam Rubio
2021-04-11 20:31   ` Junio C Hamano
2021-04-11 20:33     ` Junio C Hamano
2021-05-05  9:04     ` Christian Couder
2021-05-04 17:26   ` Andrzej Hunt
2021-05-05  2:04     ` Junio C Hamano [this message]
2021-04-11  9:55 ` [PATCH v3 4/4] bisect--helper: retire `--bisect-next-check` subcommand Miriam Rubio

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

  List information: http://vger.kernel.org/majordomo-info.html

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=xmqqzgxa3pij.fsf@gitster.g \
    --to=gitster@pobox.com \
    --cc=andrzej@ahunt.org \
    --cc=chriscool@tuxfamily.org \
    --cc=git@vger.kernel.org \
    --cc=mirucam@gmail.com \
    --cc=tanushreetumane@gmail.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
Code repositories for project(s) associated with this public inbox

	https://80x24.org/mirrors/git.git

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).