From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0D752C4CEC6 for ; Thu, 12 Sep 2019 14:16:33 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id D80CE20684 for ; Thu, 12 Sep 2019 14:16:32 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D80CE20684 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:34980 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1i8Ptf-00017Y-OQ for qemu-devel@archiver.kernel.org; Thu, 12 Sep 2019 10:16:31 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:41682) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1i8PaX-0006Uu-Ba for qemu-devel@nongnu.org; Thu, 12 Sep 2019 09:56:46 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1i8PaW-0006NE-9P for qemu-devel@nongnu.org; Thu, 12 Sep 2019 09:56:45 -0400 Received: from mx1.redhat.com ([209.132.183.28]:34690) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1i8PaU-0006Lj-2q; Thu, 12 Sep 2019 09:56:42 -0400 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 6D60F8E581; Thu, 12 Sep 2019 13:56:41 +0000 (UTC) Received: from localhost (unknown [10.40.205.22]) by smtp.corp.redhat.com (Postfix) with ESMTPS id A29AE600C4; Thu, 12 Sep 2019 13:56:40 +0000 (UTC) From: Max Reitz To: qemu-block@nongnu.org Date: Thu, 12 Sep 2019 15:56:29 +0200 Message-Id: <20190912135632.13925-2-mreitz@redhat.com> In-Reply-To: <20190912135632.13925-1-mreitz@redhat.com> References: <20190912135632.13925-1-mreitz@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 [10.5.110.28]); Thu, 12 Sep 2019 13:56:41 +0000 (UTC) Content-Transfer-Encoding: quoted-printable X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: [Qemu-devel] [PATCH 1/4] mirror: Do not dereference invalid pointers X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Kevin Wolf , John Snow , qemu-devel@nongnu.org, Markus Armbruster , Max Reitz Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" mirror_exit_common() may be called twice (if it is called from mirror_prepare() and fails, it will be called from mirror_abort() again). In such a case, many of the pointers in the MirrorBlockJob object will already be freed. This can be seen most reliably for s->target, which is set to NULL (and then dereferenced by blk_bs()). Cc: qemu-stable@nongnu.org Fixes: 737efc1eda23b904fbe0e66b37715fb0e5c3e58b Signed-off-by: Max Reitz --- block/mirror.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-) diff --git a/block/mirror.c b/block/mirror.c index fe984efb90..706d80fced 100644 --- a/block/mirror.c +++ b/block/mirror.c @@ -620,11 +620,11 @@ static int mirror_exit_common(Job *job) { MirrorBlockJob *s =3D container_of(job, MirrorBlockJob, common.job); BlockJob *bjob =3D &s->common; - MirrorBDSOpaque *bs_opaque =3D s->mirror_top_bs->opaque; + MirrorBDSOpaque *bs_opaque; AioContext *replace_aio_context =3D NULL; - BlockDriverState *src =3D s->mirror_top_bs->backing->bs; - BlockDriverState *target_bs =3D blk_bs(s->target); - BlockDriverState *mirror_top_bs =3D s->mirror_top_bs; + BlockDriverState *src; + BlockDriverState *target_bs; + BlockDriverState *mirror_top_bs; Error *local_err =3D NULL; bool abort =3D job->ret < 0; int ret =3D 0; @@ -634,6 +634,11 @@ static int mirror_exit_common(Job *job) } s->prepared =3D true; =20 + mirror_top_bs =3D s->mirror_top_bs; + bs_opaque =3D mirror_top_bs->opaque; + src =3D mirror_top_bs->backing->bs; + target_bs =3D blk_bs(s->target); + if (bdrv_chain_contains(src, target_bs)) { bdrv_unfreeze_backing_chain(mirror_top_bs, target_bs); } --=20 2.21.0