From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 085A6C433FF for ; Wed, 14 Aug 2019 12:29:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CDA4C2084D for ; Wed, 14 Aug 2019 12:29:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727623AbfHNM3R (ORCPT ); Wed, 14 Aug 2019 08:29:17 -0400 Received: from mx1.redhat.com ([209.132.183.28]:38570 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725800AbfHNM3R (ORCPT ); Wed, 14 Aug 2019 08:29:17 -0400 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id ED579300D209; Wed, 14 Aug 2019 12:29:16 +0000 (UTC) Received: from dhcp-27-174.brq.redhat.com (unknown [10.43.17.136]) by smtp.corp.redhat.com (Postfix) with SMTP id 7D88B80697; Wed, 14 Aug 2019 12:29:11 +0000 (UTC) Received: by dhcp-27-174.brq.redhat.com (nbSMTP-1.00) for uid 1000 oleg@redhat.com; Wed, 14 Aug 2019 14:29:16 +0200 (CEST) Date: Wed, 14 Aug 2019 14:29:10 +0200 From: Oleg Nesterov To: christian.brauner@ubuntu.com Cc: linux-kernel@vger.kernel.org, libc-alpha@sourceware.org, alistair23@gmail.com, ebiederm@xmission.com, arnd@arndb.de, dalias@libc.org, torvalds@linux-foundation.org, adhemerval.zanella@linaro.org, fweimer@redhat.com, palmer@sifive.com, macro@wdc.com, zongbox@gmail.com, akpm@linux-foundation.org, viro@zeniv.linux.org.uk, hpa@zytor.com Subject: Re: [PATCH v1 1/1] waitid: Add support for waiting for the current process group Message-ID: <20190814122909.GA11595@redhat.com> References: <20190814113822.9505-1-christian.brauner@ubuntu.com> <20190814113822.9505-2-christian.brauner@ubuntu.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190814113822.9505-2-christian.brauner@ubuntu.com> User-Agent: Mutt/1.5.24 (2015-08-30) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.40]); Wed, 14 Aug 2019 12:29:17 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 08/14, christian.brauner@ubuntu.com wrote: > > case P_PGID: > type = PIDTYPE_PGID; > - if (upid <= 0) > + if (upid < 0) > return -EINVAL; > + > + if (upid == 0) > + pid = get_pid(task_pgrp(current)); this needs rcu lock or tasklist_lock, this can race with another thread doing sys_setpgid/setsid (see change_pid(PIDTYPE_PGID)). Oleg.