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From: Oleg Nesterov <oleg@redhat.com>
To: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: linux-kernel@vger.kernel.org,
	Christof Meerwald <cmeerw@cmeerw.org>,
	Linux Containers <containers@lists.linux-foundation.org>
Subject: Re: [PATCH] signal: Avoid corrupting si_pid and si_uid in do_notify_parent
Date: Tue, 21 Apr 2020 11:04:27 +0200
Message-ID: <20200421090426.GA6787@redhat.com> (raw)
In-Reply-To: <87sggyytnh.fsf@x220.int.ebiederm.org>

On 04/20, Eric W. Biederman wrote:
>
> The immediate problem is as Christof noticed that "pid_alive(current) == false".

this is slightly offtopic, but we can probably remove this "pid_alive" check,
pid_nr_ns() checks pid != NULL anyway.

> Inspecting the code it appears this problem has existed since the pid
> namespace support started handling this case

Agreed...

> @@ -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.
> +	 */
>  	if (valid_signal(sig) && sig)
> -		__group_send_sig_info(sig, &info, tsk->parent);
> +		__send_signal(sig, &info, tsk->parent, PIDTYPE_TGID, false);

Acked-by: Oleg Nesterov <oleg@redhat.com>


  parent 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
2020-04-21  9:04   ` Oleg Nesterov [this message]
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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