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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 22771C43334 for ; Thu, 2 Jun 2022 19:05:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238352AbiFBTFM (ORCPT ); Thu, 2 Jun 2022 15:05:12 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58960 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238396AbiFBTFB (ORCPT ); Thu, 2 Jun 2022 15:05:01 -0400 Received: from mx0a-001b2d01.pphosted.com (mx0b-001b2d01.pphosted.com [148.163.158.5]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B31FE1179; Thu, 2 Jun 2022 12:04:59 -0700 (PDT) Received: from pps.filterd (m0098414.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.17.1.5/8.17.1.5) with ESMTP id 252H6JSk015034; Thu, 2 Jun 2022 19:04:56 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ibm.com; h=message-id : date : mime-version : subject : to : cc : references : from : in-reply-to : content-type : content-transfer-encoding; s=pp1; bh=DukZOSDWRVxHTmZ8S12svqlnqdU+zUS7/m0tvzHawqo=; b=q5EsPytjwYo4883MFAxSh3c+mVCJjIoGvcSudxpwxg0GorxcKf1JJuIGM+wdoOlo6ZEI K8j6i2Hhaw+FVIPqFN4Gr7pHB/7GPkcKp+MisSJfRKwLnJf9EmXJ4C6n0NaU5eyD8xG0 8zSrYo/LSC8NpxujQUqPdny3YlOt276qurEqG79fWtbHl7EWI+oGxtzU5U7M8+KLn0LK zzKqFsNnmArTGpbjWWbLMU/dCJp8/hSQedV3t64zfJayILHwpcGxFp9xTs8vuPiZOKOf 1PHWgmuLR//jFcUJIPhgocv0O4+xnWbedkwNInPKwwBJLcpxUMpmxz7KPoCZ5N6+7vgK Jg== Received: from pps.reinject (localhost [127.0.0.1]) by mx0b-001b2d01.pphosted.com (PPS) with ESMTPS id 3gevu4qx1d-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Thu, 02 Jun 2022 19:04:55 +0000 Received: from m0098414.ppops.net (m0098414.ppops.net [127.0.0.1]) by pps.reinject (8.17.1.5/8.17.1.5) with ESMTP id 252Iw4dU014113; Thu, 2 Jun 2022 19:04:55 GMT Received: from ppma02dal.us.ibm.com (a.bd.3ea9.ip4.static.sl-reverse.com [169.62.189.10]) by mx0b-001b2d01.pphosted.com (PPS) with ESMTPS id 3gevu4qx15-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Thu, 02 Jun 2022 19:04:55 +0000 Received: from pps.filterd (ppma02dal.us.ibm.com [127.0.0.1]) by ppma02dal.us.ibm.com (8.16.1.2/8.16.1.2) with SMTP id 252IowNh028904; Thu, 2 Jun 2022 19:04:54 GMT Received: from b03cxnp08027.gho.boulder.ibm.com (b03cxnp08027.gho.boulder.ibm.com [9.17.130.19]) by ppma02dal.us.ibm.com with ESMTP id 3gd1adbd7p-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Thu, 02 Jun 2022 19:04:54 +0000 Received: from b03ledav004.gho.boulder.ibm.com (b03ledav004.gho.boulder.ibm.com [9.17.130.235]) by b03cxnp08027.gho.boulder.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 252J4qM613697758 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 2 Jun 2022 19:04:53 GMT Received: from b03ledav004.gho.boulder.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id DF66A78064; Thu, 2 Jun 2022 19:04:52 +0000 (GMT) Received: from b03ledav004.gho.boulder.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 0D2417805C; Thu, 2 Jun 2022 19:04:52 +0000 (GMT) Received: from [9.211.104.178] (unknown [9.211.104.178]) by b03ledav004.gho.boulder.ibm.com (Postfix) with ESMTP; Thu, 2 Jun 2022 19:04:51 +0000 (GMT) Message-ID: Date: Thu, 2 Jun 2022 15:04:51 -0400 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.9.0 Subject: Re: [PATCH v1 08/18] vfio/ccw: Check that private pointer is not NULL Content-Language: en-US To: Eric Farman Cc: Jason Gunthorpe , Alex Williamson , Liu Yi L , Halil Pasic , kvm@vger.kernel.org, linux-s390@vger.kernel.org References: <20220602171948.2790690-1-farman@linux.ibm.com> <20220602171948.2790690-9-farman@linux.ibm.com> From: Matthew Rosato In-Reply-To: <20220602171948.2790690-9-farman@linux.ibm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: e--y6Qw8-tbBU5Kcnefai4EfUAGkW9lm X-Proofpoint-GUID: yx8jq245CzxYBIehsb6UO7X1ak0ZqsIy X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.874,Hydra:6.0.517,FMLib:17.11.64.514 definitions=2022-06-02_05,2022-06-02_01,2022-02-23_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 mlxlogscore=993 adultscore=0 clxscore=1015 impostorscore=0 mlxscore=0 phishscore=0 lowpriorityscore=0 priorityscore=1501 bulkscore=0 suspectscore=0 spamscore=0 malwarescore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2204290000 definitions=main-2206020081 Precedence: bulk List-ID: X-Mailing-List: linux-s390@vger.kernel.org On 6/2/22 1:19 PM, Eric Farman wrote: > The subchannel->dev->drvdata pointer is set in vfio_ccw_sch_probe() > and cleared in vfio_ccw_sch_remove(). In a purely defensive move, > let's check that the resultant pointer exists before operating on it > any way, since some lifecycle changes are forthcoming. > > Signed-off-by: Eric Farman > --- > drivers/s390/cio/vfio_ccw_drv.c | 12 ++++++++++++ > drivers/s390/cio/vfio_ccw_ops.c | 3 +++ > 2 files changed, 15 insertions(+) > > diff --git a/drivers/s390/cio/vfio_ccw_drv.c b/drivers/s390/cio/vfio_ccw_drv.c > index 3784eb4cda85..f8226db26e54 100644 > --- a/drivers/s390/cio/vfio_ccw_drv.c > +++ b/drivers/s390/cio/vfio_ccw_drv.c > @@ -41,6 +41,9 @@ int vfio_ccw_sch_quiesce(struct subchannel *sch) > DECLARE_COMPLETION_ONSTACK(completion); > int iretry, ret = 0; > > + if (!private) > + return 0; > + > spin_lock_irq(sch->lock); > if (!sch->schib.pmcw.ena) > goto out_unlock; > @@ -132,6 +135,9 @@ static void vfio_ccw_sch_irq(struct subchannel *sch) > { > struct vfio_ccw_private *private = dev_get_drvdata(&sch->dev); > > + if (WARN_ON(!private)) > + return; > + I wonder, why a warning here vs quietly ignoring in all the other cases? (maybe add a small comment) Also, kind of wondering what serialization is protecting the state of private (e.g. is it possible that you got a nonzero pointer from dev_get_drvdata but now it's been freed by a remove) > inc_irq_stat(IRQIO_CIO); > vfio_ccw_fsm_event(private, VFIO_CCW_EVENT_INTERRUPT); > } > @@ -260,6 +266,9 @@ static void vfio_ccw_sch_remove(struct subchannel *sch) > { > struct vfio_ccw_private *private = dev_get_drvdata(&sch->dev); > > + if (!private) > + return; > + > vfio_ccw_sch_quiesce(sch); > mdev_unregister_device(&sch->dev); > > @@ -293,6 +302,9 @@ static int vfio_ccw_sch_event(struct subchannel *sch, int process) > unsigned long flags; > int rc = -EAGAIN; > > + if (!private) > + return 0; > + > spin_lock_irqsave(sch->lock, flags); > if (!device_is_registered(&sch->dev)) > goto out_unlock; > diff --git a/drivers/s390/cio/vfio_ccw_ops.c b/drivers/s390/cio/vfio_ccw_ops.c > index 497e1b7ffd61..9e5c184eab89 100644 > --- a/drivers/s390/cio/vfio_ccw_ops.c > +++ b/drivers/s390/cio/vfio_ccw_ops.c > @@ -152,6 +152,9 @@ static void vfio_ccw_mdev_remove(struct mdev_device *mdev) > { > struct vfio_ccw_private *private = dev_get_drvdata(mdev->dev.parent); > > + if (!private) > + return; > + > VFIO_CCW_MSG_EVENT(2, "sch %x.%x.%04x: remove\n", > private->sch->schid.cssid, > private->sch->schid.ssid,