From nobody Sat Feb 7 08:21:58 2026 Delivered-To: importer@patchew.org Received-SPF: pass (zoho.com: domain of gnu.org designates 208.118.235.17 as permitted sender) client-ip=208.118.235.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Authentication-Results: mx.zohomail.com; spf=pass (zoho.com: domain of gnu.org designates 208.118.235.17 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 [208.118.235.17]) by mx.zohomail.com with SMTPS id 1546601056610596.214494154503; Fri, 4 Jan 2019 03:24:16 -0800 (PST) Received: from localhost ([127.0.0.1]:34236 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gfNaJ-0004Wr-GK for importer@patchew.org; Fri, 04 Jan 2019 06:24:15 -0500 Received: from eggs.gnu.org ([208.118.235.92]:51471) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gfNYK-0002Uk-HG for qemu-devel@nongnu.org; Fri, 04 Jan 2019 06:22:13 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1gfNYJ-0005Rj-Rg for qemu-devel@nongnu.org; Fri, 04 Jan 2019 06:22:12 -0500 Received: from mx1.redhat.com ([209.132.183.28]:33696) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1gfNYD-0005P9-WE; Fri, 04 Jan 2019 06:22:06 -0500 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 mx1.redhat.com (Postfix) with ESMTPS id 476664CE99; Fri, 4 Jan 2019 11:22:05 +0000 (UTC) Received: from localhost (ovpn-117-207.ams2.redhat.com [10.36.117.207]) by smtp.corp.redhat.com (Postfix) with ESMTP id 59C7460152; Fri, 4 Jan 2019 11:21:57 +0000 (UTC) From: Stefan Hajnoczi To: qemu-devel@nongnu.org Date: Fri, 4 Jan 2019 11:21:43 +0000 Message-Id: <20190104112145.12413-3-stefanha@redhat.com> In-Reply-To: <20190104112145.12413-1-stefanha@redhat.com> References: <20190104112145.12413-1-stefanha@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.30]); Fri, 04 Jan 2019 11:22:05 +0000 (UTC) Content-Transfer-Encoding: quoted-printable X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 209.132.183.28 Subject: [Qemu-devel] [PULL 2/4] dmg: fix binary search X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Kevin Wolf , Peter Maydell , yuchenlin , qemu-block@nongnu.org, Max Reitz , Stefan Hajnoczi Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" Content-Type: text/plain; charset="utf-8" From: yuchenlin There is a possible hang in original binary search implementation. That is if chunk1 =3D 4, chunk2 =3D 5, chunk3 =3D 4, and we go else case. The chunk1 will be still 4, and so on. Signed-off-by: yuchenlin Message-id: 20190103114700.9686-2-npes87184@gmail.com Signed-off-by: Stefan Hajnoczi --- block/dmg.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/block/dmg.c b/block/dmg.c index 2c806e3389..b26ddb1f68 100644 --- a/block/dmg.c +++ b/block/dmg.c @@ -572,16 +572,20 @@ static inline uint32_t search_chunk(BDRVDMGState *s, = uint64_t sector_num) { /* binary search */ uint32_t chunk1 =3D 0, chunk2 =3D s->n_chunks, chunk3; - while (chunk1 !=3D chunk2) { + while (chunk1 <=3D chunk2) { chunk3 =3D (chunk1 + chunk2) / 2; if (s->sectors[chunk3] > sector_num) { - chunk2 =3D chunk3; + if (chunk3 =3D=3D 0) { + goto err; + } + chunk2 =3D chunk3 - 1; } else if (s->sectors[chunk3] + s->sectorcounts[chunk3] > sector_n= um) { return chunk3; } else { - chunk1 =3D chunk3; + chunk1 =3D chunk3 + 1; } } +err: return s->n_chunks; /* error */ } =20 --=20 2.20.1