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From: Christian Brauner <christian.brauner@ubuntu.com>
To: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Linux Containers <containers@lists.linux-foundation.org>,
	Christof Meerwald <cmeerw@cmeerw.org>,
	linux-kernel@vger.kernel.org, Oleg Nesterov <oleg@redhat.com>
Subject: Re: [PATCH] signal: Avoid corrupting si_pid and si_uid in do_notify_parent
Date: Tue, 21 Apr 2020 17:08:40 +0200
Message-ID: <20200421150840.gevtsrhdec5wwg6y@wittgenstein> (raw)
In-Reply-To: <871rog6g56.fsf@x220.int.ebiederm.org>

On Tue, Apr 21, 2020 at 09:57:09AM -0500, Eric W. Biederman wrote:
> Christian Brauner <christian.brauner@ubuntu.com> writes:
> 
> > On Mon, Apr 20, 2020 at 12:05:38PM -0500, Eric W. Biederman wrote:
> >> diff --git a/kernel/signal.c b/kernel/signal.c
> >> index 9899c5f91ee1..a88a89422227 100644
> >> --- a/kernel/signal.c
> >> +++ b/kernel/signal.c
> >> @@ -1993,8 +1993,12 @@ bool do_notify_parent(struct task_struct *tsk, int sig)
> >>  		if (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN)
> >>  			sig = 0;
> >>  	}
> >> +	/*
> >> +	 * Bypass send_signal as the si_pid and si_uid values have
> >> +	 * been generated in the parent's namespaces.
> >> +	 */
> >
> > At first I misread that comment as saying that we're skipping sending a
> > signal not that it relates to a specific function (and I won't admit that
> > I wrote a whole long paragraph on why I'm confused we're skipping
> > sending signals on invalid si_pid and si_uid...).
> 
> I have updated the comment to read:
> +       /*
> +        * Send with __send_signal as si_pid and si_uid are in the
> +        * parent's namespaces.
> +        */
> 
> That should be enough of a hint for someone to read the code and figure
> out what is going on.

Perfect, thanks!
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>

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
2020-04-21 10:28     ` Christian Brauner
2020-04-21 14:57     ` Eric W. Biederman
2020-04-21 15:08       ` Christian Brauner [this message]
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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