From: ebiederm@xmission.com (Eric W. Biederman)
To: Oleg Nesterov <oleg@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Louis Rilling <louis.rilling@kerlabs.com>,
Pavel Emelyanov <xemul@openvz.org>,
Linux Containers <containers@lists.osdl.org>,
linux-kernel@vger.kernel.org,
Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Subject: Re: [PATCH 1/1] pid_ns: move pid_ns_release_proc() from proc_flush_task() to zap_pid_ns_processes()
Date: Thu, 24 Jun 2010 00:06:57 -0700 [thread overview]
Message-ID: <m1zkykgb8u.fsf@fess.ebiederm.org> (raw)
In-Reply-To: <20100623203735.GB25298@redhat.com> (Oleg Nesterov's message of "Wed\, 23 Jun 2010 22\:37\:35 +0200")
Oleg Nesterov <oleg@redhat.com> writes:
> This is mostly cleanup and optimization, but also fixes the bug.
Oleg with respect to your other patches I think they are some of
the best ones we have on the table.
> proc_flush_task() checks upid->nr == 1 to detect the case when
> a sub-namespace exits. However, this doesn't work in case when
> a multithreaded init execs and calls release_task(old_leader),
> the old leader has the same pid 1.
>
> Move pid_ns_release_proc() to zap_pid_ns_processes(), it is called
> when we know for sure that init is exiting.
This actually guarantees a use after free for the namespace init:
do_exit()
exit_notify()
forget_original_parent()
find_new_reaper()
zap_pid_ns_processes()
release_task()
proc_flush_task()
> Note: with or without this change this mntput() can happen before the
> EXIT_DEAD tasks not visible to do_wait() have passed proc_flush_task().
> We need more fixes.
I agree.
Eric
> Signed-off-by: Oleg Nesterov <oleg@redhat.com>
> ---
>
> fs/proc/base.c | 4 ----
> kernel/pid_namespace.c | 2 ++
> 2 files changed, 2 insertions(+), 4 deletions(-)
>
> --- 35-rc3/fs/proc/base.c~PNS_5_MOVE_MNTPUT_TO_ZAP 2010-06-23 22:06:01.000000000 +0200
> +++ 35-rc3/fs/proc/base.c 2010-06-23 22:10:26.000000000 +0200
> @@ -2745,10 +2745,6 @@ void proc_flush_task(struct task_struct
> proc_flush_task_mnt(upid->ns->proc_mnt, upid->nr,
> tgid->numbers[i].nr);
> }
> -
> - upid = &pid->numbers[pid->level];
> - if (upid->nr == 1)
> - pid_ns_release_proc(upid->ns);
> }
>
> static struct dentry *proc_pid_instantiate(struct inode *dir,
> --- 35-rc3/kernel/pid_namespace.c~PNS_5_MOVE_MNTPUT_TO_ZAP 2010-06-23 22:13:07.000000000 +0200
> +++ 35-rc3/kernel/pid_namespace.c 2010-06-23 22:13:55.000000000 +0200
> @@ -189,6 +189,8 @@ void zap_pid_ns_processes(struct pid_nam
> } while (rc != -ECHILD);
>
> acct_exit_ns(pid_ns);
> + pid_ns_release_proc(pid_ns);
> +
> return;
> }
>
next prev parent reply other threads:[~2010-06-24 7:07 UTC|newest]
Thread overview: 80+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-06-16 16:34 [PATCH] procfs: Do not release pid_ns->proc_mnt too early Louis Rilling
2010-06-17 9:53 ` Pavel Emelyanov
2010-06-17 13:41 ` Eric W. Biederman
2010-06-17 14:20 ` Louis Rilling
2010-06-17 21:36 ` Oleg Nesterov
2010-06-18 8:27 ` Louis Rilling
2010-06-18 16:27 ` Oleg Nesterov
2010-06-21 11:11 ` Louis Rilling
2010-06-21 12:58 ` Eric W. Biederman
2010-06-21 14:15 ` Louis Rilling
2010-06-21 14:26 ` Eric W. Biederman
2010-06-17 21:20 ` Oleg Nesterov
2010-06-18 8:20 ` Louis Rilling
2010-06-18 11:15 ` Oleg Nesterov
2010-06-18 16:08 ` Oleg Nesterov
2010-06-18 17:33 ` Louis Rilling
2010-06-18 17:55 ` Oleg Nesterov
2010-06-18 21:23 ` Oleg Nesterov
2010-06-19 19:08 ` [PATCH 0/4] pid_ns_prepare_proc/unshare cleanups Oleg Nesterov
2010-06-19 19:09 ` [PATCH 1/4] procfs: proc_get_sb: consolidate/cleanup root_inode->pid logic Oleg Nesterov
2010-06-19 19:10 ` [PATCH 2/4] procfs: kill the global proc_mnt variable Oleg Nesterov
2010-06-19 19:10 ` [PATCH 3/4] procfs: move pid_ns_prepare_proc() from copy_process() to create_pid_namespace() Oleg Nesterov
2010-06-19 19:11 ` [PATCH RESEND 4/4] sys_unshare: simplify the not-really-implemented CLONE_THREAD/SIGHAND/VM code Oleg Nesterov
2010-06-20 8:42 ` [PATCH 0/6] Unshare support for the pid namespace Eric W. Biederman
2010-06-20 8:44 ` [PATCH 1/6] pid: Remove the child_reaper special case in init/main.c Eric W. Biederman
2010-06-20 18:29 ` Oleg Nesterov
2010-06-20 20:27 ` Oleg Nesterov
2010-06-20 8:45 ` [PATCH 2/6] pidns: Call pid_ns_prepare_proc from create_pid_namespace Eric W. Biederman
2010-06-20 18:19 ` Oleg Nesterov
2010-06-20 8:45 ` [PATCH 3/6] procfs: kill the global proc_mnt variable Eric W. Biederman
2010-06-20 8:47 ` [PATCH 4/6] pidns: Don't allow new pids after the namespace is dead Eric W. Biederman
2010-06-20 18:44 ` Oleg Nesterov
2010-06-20 8:48 ` [PATCH 5/6] pidns: Use task_active_pid_ns where appropriate Eric W. Biederman
2010-06-20 8:49 ` [PATCH 6/6] pidns: Support unsharing the pid namespace Eric W. Biederman
2010-06-20 20:14 ` Oleg Nesterov
2010-06-20 20:42 ` Oleg Nesterov
2010-06-21 1:53 ` Eric W. Biederman
2010-06-20 18:03 ` [PATCH 0/6] Unshare support for " Oleg Nesterov
2010-06-20 18:05 ` [PATCH 0/2] pid_ns_release_proc() fixes Oleg Nesterov
2010-06-20 18:06 ` [PATCH 1/2] pid_ns: move destroy_pid_namespace() into workqueue context Oleg Nesterov
2010-06-20 18:06 ` [PATCH 2/2] pid_ns: refactor the buggy pid_ns_release_proc() logic Oleg Nesterov
2010-06-20 21:00 ` [PATCH 0/6] Unshare support for the pid namespace Eric W. Biederman
2010-06-20 21:48 ` Oleg Nesterov
2010-06-20 21:56 ` Oleg Nesterov
2011-01-26 15:57 ` Daniel Lezcano
2010-06-23 20:36 ` [PATCH 0/1] pid_ns: move pid_ns_release_proc() from proc_flush_task() to zap_pid_ns_processes() Oleg Nesterov
2010-06-23 20:37 ` [PATCH 1/1] " Oleg Nesterov
2010-06-24 6:36 ` Sukadev Bhattiprolu
2010-06-24 12:59 ` Oleg Nesterov
2010-06-24 7:06 ` Eric W. Biederman [this message]
2010-06-24 13:01 ` Oleg Nesterov
2010-06-24 8:37 ` [PATCH] pid_ns: Fix proc_flush_task() accessing freed proc_mnt Louis Rilling
2010-06-24 17:08 ` [RESEND PATCH] " Louis Rilling
2010-06-24 19:18 ` Oleg Nesterov
2010-06-25 10:23 ` Louis Rilling
2010-06-25 12:21 ` Oleg Nesterov
2010-06-25 18:37 ` Sukadev Bhattiprolu
2010-06-25 19:29 ` Oleg Nesterov
2010-06-25 21:26 ` Sukadev Bhattiprolu
2010-06-25 21:27 ` Oleg Nesterov
2010-06-25 22:07 ` Sukadev Bhattiprolu
2010-07-09 4:36 ` [RFC][PATCH 1/2] pidns: Add a flag to indicate a pid namespace is dead Eric W. Biederman
2010-07-09 4:39 ` [RFC][PATCH 2/2] pidns: Remove proc flush races when a pid namespaces are exiting Eric W. Biederman
2010-07-09 12:14 ` Louis Rilling
2010-07-09 13:05 ` Eric W. Biederman
2010-07-09 14:13 ` Louis Rilling
2010-07-09 15:58 ` [PATCH 01/24] pidns: Remove races by stopping the caching of proc_mnt Eric W. Biederman
2010-07-09 22:13 ` Serge E. Hallyn
2010-07-11 14:14 ` Louis Rilling
2010-07-11 14:25 ` Eric W. Biederman
2010-07-12 18:09 ` [PATCH] pidns: Fix wait for zombies to be reaped in zap_pid_ns_processes Eric W. Biederman
2010-07-13 21:42 ` Louis Rilling
2010-07-13 22:34 ` Serge E. Hallyn
2010-07-14 1:47 ` Eric W. Biederman
2010-10-30 7:07 ` Sukadev Bhattiprolu
2010-07-14 20:53 ` Sukadev Bhattiprolu
2010-07-14 21:35 ` Eric W. Biederman
2010-06-21 11:09 ` [PATCH] procfs: Do not release pid_ns->proc_mnt too early Louis Rilling
2010-06-21 11:15 ` Louis Rilling
2010-06-21 14:38 ` Oleg Nesterov
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