From nobody Sun Oct 5 17:32:17 2025 Delivered-To: importer@patchew.org Authentication-Results: mx.zohomail.com; dkim=fail; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=fail(p=none dis=none) header.from=redhat.com Return-Path: Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 1637016080415361.9432108719752; Mon, 15 Nov 2021 14:41:20 -0800 (PST) Received: from localhost ([::1]:39436 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1mmkf9-0000Ar-DD for importer@patchew.org; Mon, 15 Nov 2021 17:41:19 -0500 Received: from eggs.gnu.org ([209.51.188.92]:55460) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mmkdk-0007Io-Qw for qemu-devel@nongnu.org; Mon, 15 Nov 2021 17:39:52 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:32952) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mmkdj-00034E-2J for qemu-devel@nongnu.org; Mon, 15 Nov 2021 17:39:52 -0500 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-428-xDHcbEpiPfmBACP06ivkPw-1; Mon, 15 Nov 2021 17:39:47 -0500 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 3C2D61006AA0; Mon, 15 Nov 2021 22:39:46 +0000 (UTC) Received: from blue.redhat.com (ovpn-114-146.phx2.redhat.com [10.3.114.146]) by smtp.corp.redhat.com (Postfix) with ESMTP id A4D82ADCD; Mon, 15 Nov 2021 22:39:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1637015990; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=/A6PQvKS7Qjxo0EjasRHuFb0dkWFWTM912+tsj8k/+0=; b=TLt7qdUzfA8jflrN8o2N+mvPzguuybop6pobRLmrgqna+lsm1ABSDDXi0E3CBC3lZPDv35 0jii+fad3fXCscv5aP89TNG1guEW1uQlkLi90FqXRIJiIIxo5zlzhNuAzfPQW894OaAqQW JlPwhI/t3OZlSKk75QpE7zM2ikGdVyo= X-MC-Unique: xDHcbEpiPfmBACP06ivkPw-1 From: Eric Blake To: qemu-devel@nongnu.org Subject: [PATCH for 6.2] nbd/server: Silence clang sanitizer warning Date: Mon, 15 Nov 2021 16:39:43 -0600 Message-Id: <20211115223943.626416-1-eblake@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=eblake@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: quoted-printable Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=170.10.133.124; envelope-from=eblake@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -34 X-Spam_score: -3.5 X-Spam_bar: --- X-Spam_report: (-3.5 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.7, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H2=-0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=unavailable autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Peter Maydell , Vladimir Sementsov-Ogievskiy , "open list:Network Block Dev..." Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail-DKIM: fail (Header signature does not verify) X-ZM-MESSAGEID: 1637016082891100001 Content-Type: text/plain; charset="utf-8" clang's sanitizer is picky: memset(NULL, x, 0) is technically undefined behavior, even though no sane implementation of memset() deferences the NULL. Caught by the nbd-qemu-allocation iotest. The alternative to checking before each memset is to instead force an allocation of 1 element instead of g_new0(type, 0)'s behavior of returning NULL for a 0-length array. Reported-by: Peter Maydell Fixes: 3b1f244c59 (nbd: Allow export of multiple bitmaps for one device) Signed-off-by: Eric Blake Reviewed-by: Philippe Mathieu-Daud=C3=A9 --- nbd/server.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-) diff --git a/nbd/server.c b/nbd/server.c index 6d03e8a4b436..d9164ee6d0da 100644 --- a/nbd/server.c +++ b/nbd/server.c @@ -1,5 +1,5 @@ /* - * Copyright (C) 2016-2020 Red Hat, Inc. + * Copyright (C) 2016-2021 Red Hat, Inc. * Copyright (C) 2005 Anthony Liguori * * Network Block Device Server Side @@ -879,7 +879,9 @@ static bool nbd_meta_qemu_query(NBDClient *client, NBDE= xportMetaContexts *meta, if (!*query) { if (client->opt =3D=3D NBD_OPT_LIST_META_CONTEXT) { meta->allocation_depth =3D meta->exp->allocation_depth; - memset(meta->bitmaps, 1, meta->exp->nr_export_bitmaps); + if (meta->exp->nr_export_bitmaps) { + memset(meta->bitmaps, 1, meta->exp->nr_export_bitmaps); + } } trace_nbd_negotiate_meta_query_parse("empty"); return true; @@ -894,7 +896,8 @@ static bool nbd_meta_qemu_query(NBDClient *client, NBDE= xportMetaContexts *meta, if (nbd_strshift(&query, "dirty-bitmap:")) { trace_nbd_negotiate_meta_query_parse("dirty-bitmap:"); if (!*query) { - if (client->opt =3D=3D NBD_OPT_LIST_META_CONTEXT) { + if (client->opt =3D=3D NBD_OPT_LIST_META_CONTEXT && + meta->exp->nr_export_bitmaps) { memset(meta->bitmaps, 1, meta->exp->nr_export_bitmaps); } trace_nbd_negotiate_meta_query_parse("empty"); @@ -1024,7 +1027,9 @@ static int nbd_negotiate_meta_queries(NBDClient *clie= nt, /* enable all known contexts */ meta->base_allocation =3D true; meta->allocation_depth =3D meta->exp->allocation_depth; - memset(meta->bitmaps, 1, meta->exp->nr_export_bitmaps); + if (meta->exp->nr_export_bitmaps) { + memset(meta->bitmaps, 1, meta->exp->nr_export_bitmaps); + } } else { for (i =3D 0; i < nb_queries; ++i) { ret =3D nbd_negotiate_meta_query(client, meta, errp); --=20 2.33.1