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 [170.10.133.124]) by sourceware.org (Postfix) with ESMTP id 535C53857821 for ; Mon, 10 May 2021 08:44:42 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.3.2 sourceware.org 535C53857821 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-38-HaU-IPiqPP-TWgzrnX7iYw-1; Mon, 10 May 2021 04:44:40 -0400 X-MC-Unique: HaU-IPiqPP-TWgzrnX7iYw-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 E893310059CA; Mon, 10 May 2021 08:44:38 +0000 (UTC) Received: from oldenburg.str.redhat.com (ovpn-112-137.ams2.redhat.com [10.36.112.137]) by smtp.corp.redhat.com (Postfix) with ESMTPS id E7A3D5D9CA; Mon, 10 May 2021 08:44:37 +0000 (UTC) From: Florian Weimer To: Martin Sebor via Libc-alpha Cc: Martin Sebor , Joseph Myers Subject: Re: [PATCH] more out of bounds checking improvements References: <176ba75f-4299-073f-8319-66dbf9fe3f42@gmail.com> <87k0ot9trs.fsf@oldenburg.str.redhat.com> <87v98d6ldm.fsf@oldenburg.str.redhat.com> <2a7e377d-60c8-313b-9422-6cd0b4f5224c@gmail.com> Date: Mon, 10 May 2021 10:45:03 +0200 In-Reply-To: (Martin Sebor via Libc-alpha's message of "Thu, 6 May 2021 11:03:49 -0600") Message-ID: <87fsyvf04w.fsf@oldenburg.str.redhat.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.2 (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=-12.8 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_LOW, 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, 10 May 2021 08:44:43 -0000 * Martin Sebor via Libc-alpha: > diff --git a/nss/makedb.c b/nss/makedb.c > index 74edb749cf..9389f6b548 100644 > --- a/nss/makedb.c > +++ b/nss/makedb.c > @@ -747,7 +747,8 @@ write_output (int fd) > header->valstrlen = valstrlen; > > size_t filled_dbs = 0; > - struct iovec iov[2 + ndatabases * 3]; > + size_t iov_nelts = 2 + ndatabases * 3; > + struct iovec iov[iov_nelts]; > iov[0].iov_base = header; > iov[0].iov_len = file_offset; > > @@ -791,7 +792,9 @@ write_output (int fd) > + nhashentries_total * sizeof (stridx_t))); > header->allocate = file_offset; > > - if (writev (fd, iov, 2 + ndatabases * 3) != keydataoffset) > + /* Help GCC 10 see iov_nelts doesn't overflow the writev argument. */ > + assert (iov_nelts <= INT_MAX); > + if (writev (fd, iov, iov_nelts) != keydataoffset) > { > error (0, errno, gettext ("failed to write new database file")); > return EXIT_FAILURE; I don't think you should use assert to suppress compiler warnings because we are supposed to have warning-free builds even with -DNDEBUG (although it's likely that other problems exist). Thanks, Florian