From nobody Fri May 3 14:57:16 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@nongnu.org; helo=lists.gnu.org; Authentication-Results: mx.zoho.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; Return-Path: Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) by mx.zohomail.com with SMTPS id 1495103357315282.48262606759135; Thu, 18 May 2017 03:29:17 -0700 (PDT) Received: from localhost ([::1]:52871 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dBIgF-0007Iv-Mq for importer@patchew.org; Thu, 18 May 2017 06:29:15 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:45036) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dBIfN-0006vu-3n for qemu-devel@nongnu.org; Thu, 18 May 2017 06:28:22 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1dBIfK-0002nb-22 for qemu-devel@nongnu.org; Thu, 18 May 2017 06:28:21 -0400 Received: from mx1.redhat.com ([209.132.183.28]:40648) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1dBIfJ-0002n4-SI; Thu, 18 May 2017 06:28:17 -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 BDB705F795; Thu, 18 May 2017 10:28:16 +0000 (UTC) Received: from lemon.redhat.com (ovpn-12-70.pek2.redhat.com [10.72.12.70]) by smtp.corp.redhat.com (Postfix) with ESMTP id 7470B19EE6; Thu, 18 May 2017 10:28:10 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com BDB705F795 Authentication-Results: ext-mx10.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx10.extmail.prod.ext.phx2.redhat.com; spf=pass smtp.mailfrom=famz@redhat.com DKIM-Filter: OpenDKIM Filter v2.11.0 mx1.redhat.com BDB705F795 From: Fam Zheng To: qemu-devel@nongnu.org Date: Thu, 18 May 2017 18:28:08 +0800 Message-Id: <20170518102808.30046-1-famz@redhat.com> 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 [10.5.110.39]); Thu, 18 May 2017 10:28:16 +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 Subject: [Qemu-devel] [PATCH] virtio-scsi: Unset hotplug handler when unrealize 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: Paolo Bonzini , qemu-stable@nongnu.org, "Michael S. Tsirkin" Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.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" This matches the qbus_set_hotplug_handler in realize and is important to release the final reference to the embedded VirtIODevice so that it is properly finalized. A use-after-free is fixed with this patch, indirectly: virtio_device_instance_finalize wasn't called at hot-unplug, and the vdev->listener would be a dangling pointer in the global and the per address space listener list. See also RHBZ 1449031. Thanks to Paolo for explaining the reference counting. Cc: qemu-stable@nongnu.org Signed-off-by: Fam Zheng --- Like suggested by Paolo, it seems to make sense to do this clean up in bus_unparent, but given how confused I got when working on this bug, I'm not confident in my reasoning about the ref count balance in other callers. --- hw/scsi/virtio-scsi.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/hw/scsi/virtio-scsi.c b/hw/scsi/virtio-scsi.c index 46a3e3f..f46f06d 100644 --- a/hw/scsi/virtio-scsi.c +++ b/hw/scsi/virtio-scsi.c @@ -918,6 +918,9 @@ void virtio_scsi_common_unrealize(DeviceState *dev, Err= or **errp) =20 static void virtio_scsi_device_unrealize(DeviceState *dev, Error **errp) { + VirtIOSCSI *s =3D VIRTIO_SCSI(dev); + + qbus_set_hotplug_handler(BUS(&s->bus), NULL, &error_abort); virtio_scsi_common_unrealize(dev, errp); } =20 --=20 2.9.3