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=-2.4 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 E7D22C54FC9 for ; Tue, 21 Apr 2020 11:28:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B92D6206B8 for ; Tue, 21 Apr 2020 11:28:40 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="hIFpCxzS" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728621AbgDUL2k (ORCPT ); Tue, 21 Apr 2020 07:28:40 -0400 Received: from us-smtp-2.mimecast.com ([207.211.31.81]:34650 "EHLO us-smtp-delivery-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726018AbgDUL2j (ORCPT ); Tue, 21 Apr 2020 07:28:39 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1587468518; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=fi9gazHfvgbNH4vVnBQ4u/0lTDUCnMDsJilS89wFh+E=; b=hIFpCxzSXNHuWZnaRby4PCOj3cmbz64Xuw9hGnt1b2OfgLykjYw03goNnfmcKWP68Oz6Pc Mfl8HKgFCw3g6dqJODiJ+31ugxcowbfH/j1gO2eDmgF2mWhUsLDLoSCd9bgTqWUPDB8zDB b+JDlmv3cA3xOanteLw64jEQyeAsJag= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-61-plzc8nxCN7yl48DFpeXF-w-1; Tue, 21 Apr 2020 07:28:35 -0400 X-MC-Unique: plzc8nxCN7yl48DFpeXF-w-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id C71D61B18BC0; Tue, 21 Apr 2020 11:28:33 +0000 (UTC) Received: from dhcp-27-174.brq.redhat.com (unknown [10.40.195.130]) by smtp.corp.redhat.com (Postfix) with SMTP id 7EB6219C58; Tue, 21 Apr 2020 11:28:32 +0000 (UTC) Received: by dhcp-27-174.brq.redhat.com (nbSMTP-1.00) for uid 1000 oleg@redhat.com; Tue, 21 Apr 2020 13:28:33 +0200 (CEST) Date: Tue, 21 Apr 2020 13:28:31 +0200 From: Oleg Nesterov To: Christian Brauner Cc: "Eric W. Biederman" , linux-kernel@vger.kernel.org, Linux Containers , Christof Meerwald Subject: Re: [PATCH] signal: Avoid corrupting si_pid and si_uid in do_notify_parent Message-ID: <20200421112831.GD6787@redhat.com> References: <20200419201336.GI22017@edge.cmeerw.net> <87sggyytnh.fsf@x220.int.ebiederm.org> <20200421083031.5wapruzncjkagvhf@wittgenstein> <20200421092846.GB6787@redhat.com> <20200421102104.6pt34jknxmtu5ygm@wittgenstein> <20200421111139.GC6787@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200421111139.GC6787@redhat.com> User-Agent: Mutt/1.5.24 (2015-08-30) X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. Oleg.