From: Oleg Nesterov <oleg@redhat.com>
To: Salman Qazi <sqazi@google.com>
Cc: taviso@google.com, Roland Dreier <rolandd@cisco.com>,
Andrew Morton <akpm@linux-foundation.org>,
Roland McGrath <roland@redhat.com>,
linux-kernel@vger.kernel.org
Subject: Re: Race in ptrace.
Date: Thu, 11 Feb 2010 19:55:30 +0100 [thread overview]
Message-ID: <20100211185530.GA22055@redhat.com> (raw)
In-Reply-To: <4352991a1002111043l35f1c1b5mcd9ad4c76f6351a7@mail.gmail.com>
On 02/11, Salman Qazi wrote:
>
> >> > // the tracee is STOPPED as requested, not TRACED,
> >> > // SIGCONT wakes it up
> >> > kill(pid, SIGCONT);
>
> I am still missing something. There's probably a gap in my
> understanding, so let's try to clarify it. The last "kill" call,
> sends a SIGCONT. But, shouldn't this SIGCONT be intercepted by the
> tracer before the tracee sees it?
No. The tracee resumes (again: because it was STOPPED, not TRACED),
dequeues SIGCONT, reports the signal and stops in TASK_TRACED,
see ptrace_signal(). Meanwhile, until it calls ptrace_stop(), it is
TASK_RUNNING and ptrace() fails.
Oleg.
next prev parent reply other threads:[~2010-02-11 18:57 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-02-08 22:16 Race in ptrace Salman Qazi
[not found] ` <20100208143231.6d804590.akpm@linux-foundation.org>
2010-02-09 11:27 ` Oleg Nesterov
2010-02-10 13:35 ` Oleg Nesterov
2010-02-10 18:38 ` Salman Qazi
2010-02-11 12:56 ` Oleg Nesterov
2010-02-11 16:32 ` Salman Qazi
2010-02-11 16:50 ` Oleg Nesterov
2010-02-11 18:43 ` Salman Qazi
2010-02-11 18:55 ` Oleg Nesterov [this message]
2010-02-11 19:08 ` Salman Qazi
2010-02-11 20:10 ` Oleg Nesterov
2010-02-11 20:39 ` Salman Qazi
2010-02-11 20:55 ` Roland McGrath
2010-02-11 21:05 ` Salman Qazi
2010-02-11 20:59 ` Oleg Nesterov
-- strict thread matches above, loose matches on Subject: below --
2010-02-08 22:04 Salman Qazi
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
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20100211185530.GA22055@redhat.com \
--to=oleg@redhat.com \
--cc=akpm@linux-foundation.org \
--cc=linux-kernel@vger.kernel.org \
--cc=roland@redhat.com \
--cc=rolandd@cisco.com \
--cc=sqazi@google.com \
--cc=taviso@google.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.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox