From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: 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 8EC69386F41A for ; Mon, 23 Nov 2020 16:44:27 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.3.2 sourceware.org 8EC69386F41A 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-337-l1dkqrgUNAC1LxqKQed1EQ-1; Mon, 23 Nov 2020 11:44:25 -0500 X-MC-Unique: l1dkqrgUNAC1LxqKQed1EQ-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 796791868409; Mon, 23 Nov 2020 16:44:24 +0000 (UTC) Received: from oldenburg2.str.redhat.com (ovpn-112-141.ams2.redhat.com [10.36.112.141]) by smtp.corp.redhat.com (Postfix) with ESMTPS id C286C5D9E2; Mon, 23 Nov 2020 16:44:23 +0000 (UTC) From: Florian Weimer To: Topi Miettinen via Libc-alpha Cc: Topi Miettinen Subject: Re: [RFC PATCH 0/3] Improved ALSR References: <20201004130938.64575-1-toiwoton@gmail.com> Date: Mon, 23 Nov 2020 17:44:22 +0100 In-Reply-To: <20201004130938.64575-1-toiwoton@gmail.com> (Topi Miettinen via Libc-alpha's message of "Sun, 4 Oct 2020 16:09:35 +0300") Message-ID: <87v9dw58gp.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 10.5.11.14 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain X-Spam-Status: No, score=-6.2 required=5.0 tests=BAYES_00, DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, RCVD_IN_DNSWL_NONE, RCVD_IN_MSPIKE_H3, RCVD_IN_MSPIKE_WL, SPF_HELO_NONE, SPF_PASS, TXREP autolearn=ham autolearn_force=no version=3.4.2 X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on server2.sourceware.org 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: , X-List-Received-Date: Mon, 23 Nov 2020 16:44:28 -0000 * Topi Miettinen via Libc-alpha: > Problem with using sbrk() for allocations is that the location of the > memory is relatively predicatable since it's always located next to > data segment. This series makes malloc() and TCB use mmap() instead. Doesn't switching to mmap trade one (relatively) fixed offset for another? I think anonymous mmap is not randomized independently from the file mappings used for loading DSOs. And the series only changes the TCB allocation for the main thread. Fixing thread TCB/stack collocation is a completely different matter (and probably the more significant issue than lack of ASLR). 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