From: Ted Estes <ted@softwarecrafters.com>
To: "Alejandro Colomar (man-pages)" <alx.manpages@gmail.com>,
Pavel Emelyanov <xemul@openvz.org>,
Oleg Nesterov <oleg@tv-sign.ru>,
Andrew Morton <akpm@linux-foundation.org>,
Michael Kerrisk <mtk.manpages@gmail.com>,
Kees Cook <keescook@chromium.org>, Jann Horn <jann@thejh.net>
Cc: linux-man <linux-man@vger.kernel.org>,
linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: [Bug 210655] ptrace.2: documentation is incorrect about access checking threads in same thread group
Date: Tue, 15 Dec 2020 12:31:11 -0600 [thread overview]
Message-ID: <b416e106-c11d-1471-de3d-fb9d5b1b6747@softwarecrafters.com> (raw)
In-Reply-To: <feef4f9a-4ed8-8a2e-d330-88e7f516faae@gmail.com>
Per my research on the topic, the error is in the manual page. The
behavior of ptrace(2) was intentionally changed to prohibit attaching to
a thread in the same group. Apparently, there were a number of
ill-behaved edge cases.
I found this email thread on the subject:
https://lkml.org/lkml/2006/8/31/241
Thank you.
--Ted Estes
On 12/15/2020 11:01 AM, Alejandro Colomar (man-pages) wrote:
> Hi,
>
> There's a bug report: https://bugzilla.kernel.org/show_bug.cgi?id=210655
>
> [[
> Under "Ptrace access mode checking", the documentation states:
> "1. If the calling thread and the target thread are in the same thread
> group, access is always allowed."
>
> This is incorrect. A thread may never attach to another in the same group.
>
> Reference, ptrace_attach()
> https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/tree/kernel/ptrace.c?h=v5.9.14#n380
> ]]
>
> I just wanted to make sure that it is a bug in the manual page, and not
> in the implementation.
>
>
> Thanks,
>
> Alex
>
next prev parent reply other threads:[~2020-12-15 18:32 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-15 17:01 Alejandro Colomar (man-pages)
2020-12-15 18:31 ` Ted Estes [this message]
2020-12-15 18:34 ` Alejandro Colomar (man-pages)
2020-12-15 22:48 ` Alejandro Colomar (man-pages)
2020-12-16 0:55 ` Linus Torvalds
2020-12-16 7:34 ` Oleg Nesterov
2020-12-15 23:07 ` Jann Horn
2020-12-15 23:23 ` Alejandro Colomar (man-pages)
2020-12-15 23:25 ` Alejandro Colomar (man-pages)
2020-12-16 0:01 ` Jann Horn
2020-12-16 2:21 ` Ted Estes
2020-12-16 2:33 ` Jann Horn
2020-12-16 9:22 ` Alejandro Colomar (man-pages)
2020-12-17 18:45 ` Eric W. Biederman
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