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 [63.128.21.124]) by sourceware.org (Postfix) with ESMTP id 498B73850433 for ; Mon, 14 Dec 2020 14:54:19 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.3.2 sourceware.org 498B73850433 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-560-RKDjp5t6Ps2_bz4L7Amp_w-1; Mon, 14 Dec 2020 09:54:17 -0500 X-MC-Unique: RKDjp5t6Ps2_bz4L7Amp_w-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 4FDAA1934105; Mon, 14 Dec 2020 14:54:16 +0000 (UTC) Received: from oldenburg2.str.redhat.com (ovpn-112-228.ams2.redhat.com [10.36.112.228]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 78FDA6085D; Mon, 14 Dec 2020 14:54:13 +0000 (UTC) From: Florian Weimer To: Siddhesh Poyarekar via Libc-alpha Cc: Siddhesh Poyarekar , jakub@redhat.com Subject: Re: [PATCH v2 1/2] string: _FORTIFY_SOURCE=3 using __builtin_dynamic_object_size References: <11032ad8-821f-541a-4622-680b7c604458@cs.ucla.edu> <20201214052304.177490-1-siddhesh@sourceware.org> Date: Mon, 14 Dec 2020 15:54:11 +0100 In-Reply-To: <20201214052304.177490-1-siddhesh@sourceware.org> (Siddhesh Poyarekar via Libc-alpha's message of "Mon, 14 Dec 2020 10:53:04 +0530") Message-ID: <874kkocub0.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 10.5.11.13 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain X-Spam-Status: No, score=-12.1 required=5.0 tests=BAYES_00, DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, GIT_PATCH_0, RCVD_IN_DNSWL_NONE, RCVD_IN_MSPIKE_H4, 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, 14 Dec 2020 14:54:20 -0000 * Siddhesh Poyarekar via Libc-alpha: > diff --git a/NEWS b/NEWS > index 0820984547..4167f34c13 100644 > --- a/NEWS > +++ b/NEWS > @@ -28,6 +28,11 @@ Major new features: > The 32-bit RISC-V port requires at least Linux 5.4, GCC 7.1 and binutils > 2.28. > > +* A new fortification level _FORTIFY_SOURCE=3 is available. At this level, > + glibc may use additional checks that may be computationally expensive. At > + present these checks are available only on LLVM 9 and later. The latest GCC > + available at this time (10.2) does not support this level of fortification. I think it's still a fixed overhead per call (i.e., not proportional to buffer size or stack depth). So the performance warning is perhaps a bit too strong (likewise in the manual). Rest of the patch looks okay to me. Debian Code Search doesn't show any users of __objsize0 reference, so the macro name should be safe, although it does not have a __glibc_ prefix. 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