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From: Christian Brauner <christian.brauner@ubuntu.com>
To: Oleg Nesterov <oleg@redhat.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>,
	linux-kernel@vger.kernel.org,
	Linux Containers <containers@lists.linux-foundation.org>,
	Christof Meerwald <cmeerw@cmeerw.org>
Subject: Re: [PATCH] signal: Avoid corrupting si_pid and si_uid in do_notify_parent
Date: Tue, 21 Apr 2020 13:38:02 +0200
Message-ID: <20200421113802.z7f3di3qp5tyowrk@wittgenstein> (raw)
In-Reply-To: <20200421112831.GD6787@redhat.com>

On Tue, Apr 21, 2020 at 01:28:31PM +0200, Oleg Nesterov wrote:
> On 04/21, Oleg Nesterov wrote:
> >
> > The corner case is release_task() when the last exiting sub-thread sends
> > a signal on behalf of its ->group_leader, and at this point all the tsk's
> > pid pointers are NULL, that is why "force" can be falsely "true".
> 
> Or do_notify_parent() can be called by debugger from the parent namespace,
> in this case "force" can be falsely "true" too.

That's an interesting scenario to think about as well. Cross-pid-namespace
interactions are fun... That's why the cross-pid-namespace-signal
sending aspects we discussed a while back on-list though pretty nice to
have at some point are somewhat scary.

Christian

  reply index

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-04-19 20:13 SIGCHLD signal sometimes sent with si_pid==0 (Linux 5.6.5) Christof Meerwald
2020-04-20 17:05 ` [PATCH] signal: Avoid corrupting si_pid and si_uid in do_notify_parent Eric W. Biederman
2020-04-21  8:30   ` Christian Brauner
2020-04-21  9:28     ` Oleg Nesterov
2020-04-21 10:21       ` Christian Brauner
2020-04-21 11:11         ` Oleg Nesterov
2020-04-21 11:26           ` Christian Brauner
2020-04-21 12:17             ` Oleg Nesterov
2020-04-21 12:59               ` Christian Brauner
2020-04-21 13:42                 ` Eric W. Biederman
2020-04-21 11:28           ` Oleg Nesterov
2020-04-21 11:38             ` Christian Brauner [this message]
2020-04-21 10:28     ` Christian Brauner
2020-04-21 14:57     ` Eric W. Biederman
2020-04-21 15:08       ` Christian Brauner
2020-04-21  9:04   ` Oleg Nesterov
2020-04-21 10:19     ` [PATCH] remove the no longer needed pid_alive() check in __task_pid_nr_ns() Oleg Nesterov
2020-04-21 10:50       ` Christian Brauner
2020-04-21 15:05       ` Eric W. Biederman
2020-04-24 18:05         ` Oleg Nesterov
2020-04-24 19:54           ` Eric W. Biederman
2020-04-21 14:59 ` SIGCHLD signal sometimes sent with si_pid==0 (Linux 5.6.5) Eric W. Biederman

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