From patchwork Mon Oct 14 15:39:28 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Max Reitz X-Patchwork-Id: 11188981 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 2C967912 for ; Mon, 14 Oct 2019 15:42:25 +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 0CB2721848 for ; Mon, 14 Oct 2019 15:42:25 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0CB2721848 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+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Received: from localhost ([::1]:51680 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iK2UK-0001BF-7r for patchwork-qemu-devel@patchwork.kernel.org; Mon, 14 Oct 2019 11:42:24 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:60954) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iK2Rp-0005vP-OR for qemu-devel@nongnu.org; Mon, 14 Oct 2019 11:39:50 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1iK2Ro-0004Cn-ME for qemu-devel@nongnu.org; Mon, 14 Oct 2019 11:39:49 -0400 Received: from mx1.redhat.com ([209.132.183.28]:62420) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1iK2Rm-0004Ao-D0; Mon, 14 Oct 2019 11:39:46 -0400 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 885ACC049E1A; Mon, 14 Oct 2019 15:39:45 +0000 (UTC) Received: from localhost (ovpn-117-165.ams2.redhat.com [10.36.117.165]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 9A05D60BE2; Mon, 14 Oct 2019 15:39:39 +0000 (UTC) From: Max Reitz To: qemu-block@nongnu.org Subject: [PATCH v3 1/4] mirror: Do not dereference invalid pointers Date: Mon, 14 Oct 2019 17:39:28 +0200 Message-Id: <20191014153931.20699-2-mreitz@redhat.com> In-Reply-To: <20191014153931.20699-1-mreitz@redhat.com> References: <20191014153931.20699-1-mreitz@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.31]); Mon, 14 Oct 2019 15:39:45 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 209.132.183.28 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 , Vladimir Sementsov-Ogievskiy , John Snow , qemu-devel@nongnu.org, Max Reitz Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.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 Reviewed-by: John Snow Reviewed-by: Vladimir Sementsov-Ogievskiy --- 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 = container_of(job, MirrorBlockJob, common.job); BlockJob *bjob = &s->common; - MirrorBDSOpaque *bs_opaque = s->mirror_top_bs->opaque; + MirrorBDSOpaque *bs_opaque; AioContext *replace_aio_context = NULL; - BlockDriverState *src = s->mirror_top_bs->backing->bs; - BlockDriverState *target_bs = blk_bs(s->target); - BlockDriverState *mirror_top_bs = s->mirror_top_bs; + BlockDriverState *src; + BlockDriverState *target_bs; + BlockDriverState *mirror_top_bs; Error *local_err = NULL; bool abort = job->ret < 0; int ret = 0; @@ -634,6 +634,11 @@ static int mirror_exit_common(Job *job) } s->prepared = true; + mirror_top_bs = s->mirror_top_bs; + bs_opaque = mirror_top_bs->opaque; + src = mirror_top_bs->backing->bs; + target_bs = blk_bs(s->target); + if (bdrv_chain_contains(src, target_bs)) { bdrv_unfreeze_backing_chain(mirror_top_bs, target_bs); }