From nobody Tue May 7 05:58:15 2024 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@gnu.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@gnu.org Return-Path: Received: from lists.gnu.org (208.118.235.17 [208.118.235.17]) by mx.zohomail.com with SMTPS id 1506698679000413.86277607343936; Fri, 29 Sep 2017 08:24:39 -0700 (PDT) Received: from localhost ([::1]:35746 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dxx9K-0007qe-BL for importer@patchew.org; Fri, 29 Sep 2017 11:24:22 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:53421) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dxx88-0007I0-Qz for qemu-devel@nongnu.org; Fri, 29 Sep 2017 11:23:09 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1dxx85-0006nM-Md for qemu-devel@nongnu.org; Fri, 29 Sep 2017 11:23:08 -0400 Received: from mailhub.sw.ru ([195.214.232.25]:48457 helo=relay.sw.ru) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1dxx85-0006mE-6o; Fri, 29 Sep 2017 11:23:05 -0400 Received: from kvm.sw.ru (msk-vpn.virtuozzo.com [195.214.232.6]) by relay.sw.ru (8.13.4/8.13.4) with ESMTP id v8TFMtbL004836; Fri, 29 Sep 2017 18:22:56 +0300 (MSK) From: Vladimir Sementsov-Ogievskiy To: qemu-devel@nongnu.org, qemu-block@nongnu.org Date: Fri, 29 Sep 2017 18:22:55 +0300 Message-Id: <20170929152255.5431-1-vsementsov@virtuozzo.com> X-Mailer: git-send-email 2.11.1 In-Reply-To: <20170928120300.58164-1-vsementsov@virtuozzo.com> References: <20170928120300.58164-1-vsementsov@virtuozzo.com> X-detected-operating-system: by eggs.gnu.org: OpenBSD 3.x [fuzzy] X-Received-From: 195.214.232.25 Subject: [Qemu-devel] [PATCH] block/mirror: check backing in bdrv_mirror_top_flush X-BeenThere: qemu-devel@gnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: kwolf@redhat.com, jcody@redhat.com, qemu-stable@nongnu.org, mreitz@redhat.com Errors-To: qemu-devel-bounces+importer=patchew.org@gnu.org Sender: "Qemu-devel" X-ZohoMail: RSF_0 Z_629925259 SPT_0 Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Backing may be zero after failed bdrv_append in mirror_start_job, which leads to SIGSEGV. Signed-off-by: Vladimir Sementsov-Ogievskiy --- similar SIGSEGV. looks like (I guess by code, don't have full back-trace because of coroutine switch on bdrv_flush): mirror_start_job, bdrv_append failed, backing is not set=20 bdrv_unref bdrv_delete bdrv_close bdrv_flush ... bdrv_mirror_top_flush=20 Segmentation fault on return bdrv_co_flush(bs->backing->bs); as bs->backing =3D 0 block/mirror.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/block/mirror.c b/block/mirror.c index 6f5cb9f26c..f17c0d8726 100644 --- a/block/mirror.c +++ b/block/mirror.c @@ -1056,6 +1056,10 @@ static int coroutine_fn bdrv_mirror_top_pwritev(Bloc= kDriverState *bs, =20 static int coroutine_fn bdrv_mirror_top_flush(BlockDriverState *bs) { + if (bs->backing =3D=3D NULL) { + /* we can be here after failed bdrv_append in mirror_start_job */ + return 0; + } return bdrv_co_flush(bs->backing->bs); } =20 --=20 2.11.1