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 ESMTPS id E8E213858C27 for ; Thu, 11 Nov 2021 08:16:39 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org E8E213858C27 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-594-luibzyNPM7adB-_FaBaYrg-1; Thu, 11 Nov 2021 03:16:35 -0500 X-MC-Unique: luibzyNPM7adB-_FaBaYrg-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 3D23119253C7; Thu, 11 Nov 2021 08:16:34 +0000 (UTC) Received: from oldenburg.str.redhat.com (unknown [10.39.192.82]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 1980B4180; Thu, 11 Nov 2021 08:16:32 +0000 (UTC) From: Florian Weimer To: Adhemerval Zanella via Libc-alpha Cc: Adhemerval Zanella , leonardo.macchia@gmail.com Subject: Re: [PATCH 1/3] inet: Fix getnameinfo (NI_NOFQDN) race condition (BZ#28566) References: <20211110185832.1931688-1-adhemerval.zanella@linaro.org> <20211110185832.1931688-2-adhemerval.zanella@linaro.org> Date: Thu, 11 Nov 2021 09:16:31 +0100 In-Reply-To: <20211110185832.1931688-2-adhemerval.zanella@linaro.org> (Adhemerval Zanella via Libc-alpha's message of "Wed, 10 Nov 2021 15:58:30 -0300") Message-ID: <87r1bn150g.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 10.5.11.11 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain X-Spam-Status: No, score=-12.7 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_H2, SPF_HELO_NONE, SPF_NONE, TXREP autolearn=ham autolearn_force=no version=3.4.4 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) 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: Thu, 11 Nov 2021 08:16:41 -0000 * Adhemerval Zanella via Libc-alpha: > diff --git a/inet/getnameinfo.c b/inet/getnameinfo.c > index 8380d85783..58ebbb1154 100644 > --- a/inet/getnameinfo.c > +++ b/inet/getnameinfo.c > @@ -86,55 +86,75 @@ libc_freeres_ptr (static char *domain); > static char * > nrl_domainname (void) > { > + __libc_lock_define_initialized (static, lock); > + __libc_lock_lock (lock); > > + static bool not_first = false; > if (! not_first) > + done: > + scratch_buffer_free (&tmpbuf); > + not_first = true; This is missing the acquire/release pairing for the double-checked locking idiom. You can probably use the domain variable directly. > - if ((c = strchr (tmpbuf.data, '.'))) > + if (h && (c = strchr(h->h_name, '.'))) h != NULL? > + if (!scratch_buffer_grow_preserve (&tmpbuf)) I think the change to _preserve should be in the alloca elimination patch (but see my comment there). Thanks, Florian