From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on dcvr.yhbt.net X-Spam-Level: X-Spam-Status: No, score=-4.2 required=3.0 tests=AWL,BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,MAILING_LIST_MULTI, SPF_HELO_PASS,SPF_PASS shortcircuit=no autolearn=ham autolearn_force=no version=3.4.2 Received: from sourceware.org (server2.sourceware.org [8.43.85.97]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by dcvr.yhbt.net (Postfix) with ESMTPS id AF5331F4B4 for ; Wed, 14 Oct 2020 13:43:29 +0000 (UTC) Received: from server2.sourceware.org (localhost [IPv6:::1]) by sourceware.org (Postfix) with ESMTP id C0B7C384BC14; Wed, 14 Oct 2020 13:43:28 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org C0B7C384BC14 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sourceware.org; s=default; t=1602683008; bh=K56lO4SV0EusLbXCpKknNaWAr6vmulLZ5GZ7c6+yLr0=; h=To:Subject:References:Date:In-Reply-To:List-Id:List-Unsubscribe: List-Archive:List-Post:List-Help:List-Subscribe:From:Reply-To: From; b=Nx8gPImAWHf0Sr2/5kqEpINUdbcghDZ1JFgl1IHjGFbnCRKSI9wAbn1uHQ27B0Ur5 lYRLmatqwRYXiBpfkj++/5qmsURW3PtqKddgxv+oyiqXnbsIwWEeYEx+265FgnhiWs rpZivIgayob5FzPkeBSeYb0HhrVIJrHI1oN4xI6A= Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [216.205.24.124]) by sourceware.org (Postfix) with ESMTP id 89F7F3854825 for ; Wed, 14 Oct 2020 13:43:23 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.3.2 sourceware.org 89F7F3854825 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-539-gdaHl0H0NXy9Nbi0HaLpoQ-1; Wed, 14 Oct 2020 09:43:21 -0400 X-MC-Unique: gdaHl0H0NXy9Nbi0HaLpoQ-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 937641084C86; Wed, 14 Oct 2020 13:43:20 +0000 (UTC) Received: from oldenburg2.str.redhat.com (ovpn-114-103.ams2.redhat.com [10.36.114.103]) by smtp.corp.redhat.com (Postfix) with ESMTPS id D0B1660C15; Wed, 14 Oct 2020 13:43:19 +0000 (UTC) To: "H.J. Lu via Libc-alpha" Subject: Re: [PATCH] x86/CET: Update vfork to prevent child return References: <20201013175146.58558-1-hjl.tools@gmail.com> Date: Wed, 14 Oct 2020 15:43:18 +0200 In-Reply-To: <20201013175146.58558-1-hjl.tools@gmail.com> (H. J. Lu via Libc-alpha's message of "Tue, 13 Oct 2020 10:51:46 -0700") Message-ID: <87wnzsord5.fsf@oldenburg2.str.redhat.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.1 (gnu/linux) MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain X-BeenThere: libc-alpha@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libc-alpha mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , From: Florian Weimer via Libc-alpha Reply-To: Florian Weimer Errors-To: libc-alpha-bounces@sourceware.org Sender: "Libc-alpha" * H. J. Lu via Libc-alpha: > Child of vfork should either call _exit or one of the exec family of > functions. But normally there is nothing to prevent child of vfork from > return of the vfork-calling function. Simpilfy x86 vfork when shadow > stack is in use to introduce mismatched shadow stack in child of vfork > to trigger SIGSEGV when the child returns from the function in which > vfork was called. Looks reasonable to me, thanks. We'll see what breaks as a result of this. 8-/ But everything that runs into crash will already have weird bugs. Thanks, Florian -- Red Hat GmbH, https://de.redhat.com/ , Registered seat: Grasbrunn, Commercial register: Amtsgericht Muenchen, HRB 153243, Managing Directors: Charles Cachera, Brian Klemm, Laurie Krebs, Michael O'Neill