From: Oleg Nesterov <oleg@redhat.com>
To: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Aaron Tomlin <atomlin@redhat.com>,
Pavel Emelyanov <xemul@parallels.com>,
Serge Hallyn <serge.hallyn@ubuntu.com>,
Sterling Alexander <stalexan@redhat.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/2] exit: pidns: alloc_pid() leaks pid_namespace if child_reaper is exiting
Date: Tue, 25 Nov 2014 19:59:19 +0100 [thread overview]
Message-ID: <20141125185919.GA1779@redhat.com> (raw)
In-Reply-To: <87wq6j9l4s.fsf@x220.int.ebiederm.org>
On 11/25, Eric W. Biederman wrote:
>
> Oleg Nesterov <oleg@redhat.com> writes:
>
> > On 11/25, Eric W. Biederman wrote:
> >>
> >> My concern is exposing a half initialized struct pid to the world via an
> >> rcu data structure. In particular could one of the rcu users get into
> >> trouble because we haven't called get_pid_ns yet? That is unclear to me.
> >
> > They can't. This pid was fully initialized, in particular
> > pid->numbers[pid->level].ns == ns has a reference.
> >
> > Just it is not ready for put_pid() which will be called by the "owner" of
> > this pid, the caller or the new child. So in this sense it doesn't matter
> > when we call get_pid_ns(), just we need to do this before return.
>
> Or by someone calling find_get_pid() ... put_pid().
>
> Now the reference count should not hit zero in that case
Yes. this get_pid_ns() connects to atomic_set(&pid->count, 1) set by us.
> but I hate to
> think of that case separately.
OK.
> At this point, and especially since we need to Cc stable and get this
> fix backported to who knows how many kernel releases having something
> that is trivial to validate is correct is important.
OK. I'll send V2 with -stable cc'ed.
Oleg.
next prev parent reply other threads:[~2014-11-25 18:59 UTC|newest]
Thread overview: 55+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-11-07 20:14 [PATCH 0/4] proc: deuglify task_state() Oleg Nesterov
2014-11-07 20:14 ` [PATCH 1/4] proc: task_state: read cred->group_info outside of task_lock() Oleg Nesterov
2014-11-07 20:14 ` [PATCH 2/4] proc: task_state: deuglify the max_fds calculation Oleg Nesterov
2014-11-07 20:14 ` [PATCH 3/4] proc: task_state: move the main seq_printf() outside of rcu_read_lock() Oleg Nesterov
2014-11-13 18:04 ` Paul E. McKenney
2014-11-07 20:14 ` [PATCH 4/4] proc: task_state: ptrace_parent() doesn't need pid_alive() check Oleg Nesterov
2014-11-10 21:59 ` [PATCH 0/5] exit: reparent zombie fix + cleanups/optimizations Oleg Nesterov
2014-11-10 22:00 ` [PATCH 1/5] sched_show_task: fix unsafe usage of ->real_parent Oleg Nesterov
2014-11-11 10:39 ` Peter Zijlstra
2014-11-10 22:00 ` [PATCH 2/5] exit: reparent: use ->ptrace_entry rather than ->sibling for EXIT_DEAD tasks Oleg Nesterov
2014-11-10 22:00 ` [PATCH 3/5] exit: reparent: cleanup the changing of ->parent Oleg Nesterov
2014-11-10 22:00 ` [PATCH 4/5] exit: reparent: cleanup the usage of reparent_leader() Oleg Nesterov
2014-11-10 22:00 ` [PATCH 5/5] exit: ptrace: shift "reap dead" code from exit_ptrace() to forget_original_parent() Oleg Nesterov
2014-11-14 1:37 ` [PATCH 0/5] exit: more cleanups/optimizations Oleg Nesterov
2014-11-14 1:38 ` [PATCH 1/5] exit: wait: cleanup the ptrace_reparented() checks Oleg Nesterov
2014-11-14 1:38 ` [PATCH 2/5] exit: wait: don't use zombie->real_parent Oleg Nesterov
2014-11-14 1:38 ` [PATCH 3/5] exit: wait: drop tasklist_lock before psig->c* accounting Oleg Nesterov
2014-11-14 1:38 ` [PATCH 4/5] exit: release_task: fix the comment about group leader accounting Oleg Nesterov
2014-11-14 1:38 ` [PATCH 5/5] exit: proc: don't try to flush /proc/tgid/task/tgid Oleg Nesterov
2014-11-18 21:29 ` [PATCH 0/6] exit: find_new_reaper() fixes/cleanups Oleg Nesterov
2014-11-18 21:30 ` [PATCH 1/6] exit: reparent: fix the dead-parent PR_SET_CHILD_SUBREAPER reparenting Oleg Nesterov
2014-11-18 21:30 ` [PATCH 2/6] exit: reparent: fix the cross-namespace " Oleg Nesterov
2014-11-18 21:30 ` [PATCH 3/6] exit: reparent: s/while_each_thread/for_each_thread/ in find_new_reaper() Oleg Nesterov
2014-11-18 21:30 ` [PATCH 4/6] exit: reparent: document the ->has_child_subreaper checks Oleg Nesterov
2014-11-18 21:30 ` [PATCH 5/6] exit: reparent: introduce find_child_reaper() Oleg Nesterov
2014-11-18 21:30 ` [PATCH 6/6] exit: reparent: introduce find_alive_thread() Oleg Nesterov
2014-11-20 18:34 ` [PATCH 0/3] exit: avoid O(n ** 2) thread-list scan on group-exit if possible Oleg Nesterov
2014-11-20 18:34 ` [PATCH -mm 1/3] exit: reparent: avoid find_new_reaper() if no children Oleg Nesterov
2014-11-20 22:37 ` Andrew Morton
2014-11-21 20:01 ` Oleg Nesterov
2014-11-20 18:34 ` [PATCH -mm 2/3] exit: reparent: call forget_original_parent() under tasklist_lock Oleg Nesterov
2014-11-20 18:34 ` [PATCH -mm 3/3] exit: exit_notify: re-use "dead" list to autoreap current Oleg Nesterov
2014-11-24 20:06 ` [PATCH 0/2] exit/pid_ns: comments + simple fix Oleg Nesterov
2014-11-24 20:06 ` [PATCH 1/2] exit: reparent: fix/update the comments in zap_pid_ns_processes() Oleg Nesterov
2014-11-24 20:14 ` Oleg Nesterov
2014-11-24 22:07 ` Eric W. Biederman
2014-11-25 16:57 ` Oleg Nesterov
2014-11-25 17:17 ` Oleg Nesterov
2014-11-24 20:06 ` [PATCH 2/2] exit: pidns: alloc_pid() leaks pid_namespace if child_reaper is exiting Oleg Nesterov
2014-11-24 21:46 ` Eric W. Biederman
2014-11-25 17:07 ` Oleg Nesterov
2014-11-25 17:50 ` Eric W. Biederman
2014-11-25 18:15 ` Oleg Nesterov
2014-11-25 18:43 ` Eric W. Biederman
2014-11-25 18:59 ` Oleg Nesterov [this message]
2014-11-24 21:27 ` [PATCH 0/2] exit/pid_ns: comments + simple fix Eric W. Biederman
2014-11-24 21:38 ` Oleg Nesterov
2014-11-24 21:48 ` Eric W. Biederman
2014-11-25 16:57 ` Oleg Nesterov
2014-11-26 23:54 ` [PATCH v2 " Oleg Nesterov
2014-11-26 23:54 ` [PATCH v2 1/2] exit: pidns: alloc_pid() leaks pid_namespace if child_reaper is exiting Oleg Nesterov
2014-11-27 15:44 ` Eric W. Biederman
2014-11-26 23:54 ` [PATCH v2 2/2] exit: pidns: fix/update the comments in zap_pid_ns_processes() Oleg Nesterov
2014-12-01 22:39 ` Andrew Morton
2014-12-01 23:24 ` Oleg Nesterov
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=20141125185919.GA1779@redhat.com \
--to=oleg@redhat.com \
--cc=akpm@linux-foundation.org \
--cc=atomlin@redhat.com \
--cc=ebiederm@xmission.com \
--cc=linux-kernel@vger.kernel.org \
--cc=serge.hallyn@ubuntu.com \
--cc=stalexan@redhat.com \
--cc=xemul@parallels.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;
as well as URLs for NNTP newsgroup(s).