From: Oleg Nesterov <oleg@redhat.com>
To: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Aleksa Sarai <asarai@suse.com>,
Andy Lutomirski <luto@amacapital.net>,
Attila Fazekas <afazekas@redhat.com>, Jann Horn <jann@thejh.net>,
Kees Cook <keescook@chromium.org>,
Michal Hocko <mhocko@kernel.org>,
Ulrich Obergfell <uobergfe@redhat.com>,
linux-kernel@vger.kernel.org, linux-api@vger.kernel.org
Subject: Re: [RFC][PATCH 2/2] exec: If possible don't wait for ptraced threads to be reaped
Date: Mon, 3 Apr 2017 20:12:52 +0200 [thread overview]
Message-ID: <20170403181252.GA31390@redhat.com> (raw)
In-Reply-To: <877f32k5ew.fsf@xmission.com>
On 04/02, Eric W. Biederman wrote:
>
> Oleg Nesterov <oleg@redhat.com> writes:
>
> > And btw zap_other_threads(may_hang == 0) is racy. Either you need tasklist or
> > exit_notify() should set tsk->exit_state under siglock, otherwise zap() can
> > return the wrong count.
>
> zap_other_thread(tsk, 0) only gets called in the case where we don't
> care about the return value. It does not get called from fs/exec.c
I meant that may_hang == 0 implies zap_other_threads(do_count => -1) which should
return the number of threads which didn't pass exit_notify(). The returned value
can be wrong unless you change exit_notify() to set exit_state under siglock.
Oleg.
WARNING: multiple messages have this Message-ID (diff)
From: Oleg Nesterov <oleg-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
To: "Eric W. Biederman" <ebiederm-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org>
Cc: Andrew Morton
<akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>,
Aleksa Sarai <asarai-IBi9RG/b67k@public.gmane.org>,
Andy Lutomirski <luto-kltTT9wpgjJwATOyAt5JVQ@public.gmane.org>,
Attila Fazekas <afazekas-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>,
Jann Horn <jann-XZ1E9jl8jIdeoWH0uzbU5w@public.gmane.org>,
Kees Cook <keescook-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>,
Michal Hocko <mhocko-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>,
Ulrich Obergfell
<uobergfe-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>,
linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Subject: Re: [RFC][PATCH 2/2] exec: If possible don't wait for ptraced threads to be reaped
Date: Mon, 3 Apr 2017 20:12:52 +0200 [thread overview]
Message-ID: <20170403181252.GA31390@redhat.com> (raw)
In-Reply-To: <877f32k5ew.fsf-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org>
On 04/02, Eric W. Biederman wrote:
>
> Oleg Nesterov <oleg-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> writes:
>
> > And btw zap_other_threads(may_hang == 0) is racy. Either you need tasklist or
> > exit_notify() should set tsk->exit_state under siglock, otherwise zap() can
> > return the wrong count.
>
> zap_other_thread(tsk, 0) only gets called in the case where we don't
> care about the return value. It does not get called from fs/exec.c
I meant that may_hang == 0 implies zap_other_threads(do_count => -1) which should
return the number of threads which didn't pass exit_notify(). The returned value
can be wrong unless you change exit_notify() to set exit_state under siglock.
Oleg.
next prev parent reply other threads:[~2017-04-03 18:13 UTC|newest]
Thread overview: 93+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-02-13 14:14 [PATCH 0/2] fix the traced mt-exec deadlock Oleg Nesterov
2017-02-13 14:15 ` [PATCH 1/2] exec: don't wait for zombie threads with cred_guard_mutex held Oleg Nesterov
2017-02-13 16:12 ` kbuild test robot
2017-02-13 16:47 ` Oleg Nesterov
2017-02-13 16:39 ` kbuild test robot
2017-02-13 17:27 ` Mika Penttilä
2017-02-13 18:01 ` Oleg Nesterov
2017-02-13 18:04 ` [PATCH V2 " Oleg Nesterov
2017-02-16 11:42 ` Eric W. Biederman
2017-02-20 15:22 ` Oleg Nesterov
2017-02-20 15:36 ` Oleg Nesterov
2017-02-20 22:30 ` Eric W. Biederman
2017-02-21 17:53 ` Oleg Nesterov
2017-02-21 20:20 ` Eric W. Biederman
2017-02-22 17:41 ` Oleg Nesterov
2017-02-17 4:42 ` Eric W. Biederman
2017-02-20 15:50 ` Oleg Nesterov
2017-02-13 14:15 ` [PATCH 2/2] ptrace: ensure PTRACE_EVENT_EXIT won't stop if the tracee is killed by exec Oleg Nesterov
2017-02-24 16:03 ` [PATCH 0/2] fix the traced mt-exec deadlock Oleg Nesterov
2017-03-03 1:05 ` Eric W. Biederman
2017-03-03 17:33 ` Oleg Nesterov
2017-03-03 18:23 ` Eric W. Biederman
2017-03-03 18:23 ` Eric W. Biederman
2017-03-03 18:59 ` Eric W. Biederman
2017-03-03 18:59 ` Eric W. Biederman
2017-03-03 20:06 ` Eric W. Biederman
2017-03-03 20:06 ` Eric W. Biederman
2017-03-03 20:11 ` [RFC][PATCH] exec: Don't wait for ptraced threads to be reaped Eric W. Biederman
2017-03-03 20:11 ` Eric W. Biederman
2017-03-04 17:03 ` Oleg Nesterov
2017-03-30 8:07 ` Eric W. Biederman
2017-04-01 5:11 ` [RFC][PATCH 0/2] exec: Fixing ptrace'd mulit-threaded hang Eric W. Biederman
2017-04-01 5:11 ` Eric W. Biederman
2017-04-01 5:14 ` [RFC][PATCH 1/2] sighand: Count each thread group once in sighand_struct Eric W. Biederman
2017-04-01 5:14 ` Eric W. Biederman
2017-04-01 5:16 ` [RFC][PATCH 2/2] exec: If possible don't wait for ptraced threads to be reaped Eric W. Biederman
2017-04-01 5:16 ` Eric W. Biederman
2017-04-02 15:35 ` Oleg Nesterov
2017-04-02 15:35 ` Oleg Nesterov
2017-04-02 18:53 ` Eric W. Biederman
2017-04-02 18:53 ` Eric W. Biederman
2017-04-03 18:12 ` Oleg Nesterov [this message]
2017-04-03 18:12 ` Oleg Nesterov
2017-04-03 21:04 ` Eric W. Biederman
2017-04-05 16:44 ` Oleg Nesterov
2017-04-02 15:38 ` [RFC][PATCH 0/2] exec: Fixing ptrace'd mulit-threaded hang Oleg Nesterov
2017-04-02 15:38 ` Oleg Nesterov
2017-04-02 22:50 ` [RFC][PATCH v2 0/5] " Eric W. Biederman
2017-04-02 22:50 ` Eric W. Biederman
2017-04-02 22:51 ` [RFC][PATCH v2 1/5] ptrace: Don't wait in PTRACE_O_TRACEEXIT for exec or coredump Eric W. Biederman
2017-04-02 22:51 ` Eric W. Biederman
2017-04-05 16:19 ` Oleg Nesterov
2017-04-02 22:51 ` [RFC][PATCH v2 2/5] sighand: Count each thread group once in sighand_struct Eric W. Biederman
2017-04-02 22:51 ` Eric W. Biederman
2017-04-02 22:52 ` [RFC][PATCH v2 3/5] clone: Disallown CLONE_THREAD with a shared sighand_struct Eric W. Biederman
2017-04-02 22:52 ` Eric W. Biederman
2017-04-05 16:24 ` Oleg Nesterov
2017-04-05 16:24 ` Oleg Nesterov
2017-04-05 17:34 ` Eric W. Biederman
2017-04-05 18:11 ` Oleg Nesterov
2017-04-02 22:53 ` [RFC][PATCH v2 4/5] exec: If possible don't wait for ptraced threads to be reaped Eric W. Biederman
2017-04-02 22:53 ` Eric W. Biederman
2017-04-05 16:15 ` Oleg Nesterov
2017-04-02 22:57 ` [RFC][PATCH v2 5/5] signal: Don't allow accessing signal_struct by old threads after exec Eric W. Biederman
2017-04-02 22:57 ` Eric W. Biederman
2017-04-05 16:18 ` Oleg Nesterov
2017-04-05 16:18 ` Oleg Nesterov
2017-04-05 18:16 ` Eric W. Biederman
2017-04-05 18:16 ` Eric W. Biederman
2017-04-06 15:48 ` Oleg Nesterov
2017-04-06 15:48 ` Oleg Nesterov
2017-04-02 16:15 ` [RFC][PATCH] exec: Don't wait for ptraced threads to be reaped Oleg Nesterov
2017-04-02 16:15 ` Oleg Nesterov
2017-04-02 21:07 ` Eric W. Biederman
2017-04-02 21:07 ` Eric W. Biederman
2017-04-03 18:37 ` Oleg Nesterov
2017-04-03 18:37 ` Oleg Nesterov
2017-04-03 22:49 ` Eric W. Biederman
2017-04-03 22:49 ` Eric W. Biederman
2017-04-03 22:49 ` scope of cred_guard_mutex Eric W. Biederman
2017-04-03 22:49 ` Eric W. Biederman
2017-04-05 16:08 ` Oleg Nesterov
2017-04-05 16:11 ` Kees Cook
2017-04-05 17:53 ` Eric W. Biederman
2017-04-05 18:15 ` Oleg Nesterov
2017-04-06 15:55 ` Oleg Nesterov
2017-04-06 15:55 ` Oleg Nesterov
2017-04-07 22:07 ` Kees Cook
2017-04-07 22:07 ` Kees Cook
2017-09-04 3:19 ` [RFC][PATCH] exec: Don't wait for ptraced threads to be reaped Robert O'Callahan
2017-09-04 3:19 ` Robert O'Callahan
2017-03-04 16:54 ` [PATCH 0/2] fix the traced mt-exec deadlock Oleg Nesterov
2017-03-04 16:54 ` Oleg Nesterov
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