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=-2.4 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 42D74C4332D for ; Thu, 19 Mar 2020 16:01:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1A47320658 for ; Thu, 19 Mar 2020 16:01:27 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="nW7so1kV" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727884AbgCSQB0 (ORCPT ); Thu, 19 Mar 2020 12:01:26 -0400 Received: from userp2120.oracle.com ([156.151.31.85]:53194 "EHLO userp2120.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727496AbgCSQBZ (ORCPT ); Thu, 19 Mar 2020 12:01:25 -0400 Received: from pps.filterd (userp2120.oracle.com [127.0.0.1]) by userp2120.oracle.com (8.16.0.42/8.16.0.42) with SMTP id 02JFtwdC062863; Thu, 19 Mar 2020 16:01:15 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=subject : to : cc : references : from : message-id : date : mime-version : in-reply-to : content-type : content-transfer-encoding; s=corp-2020-01-29; bh=tHGRux1eakIQEtpuMlP/9xx4wD3CXDV5MuFjhTwSK1w=; b=nW7so1kVOtpmW0J0VkL+8AD9DSPH6SU0jaVq3+sEU0BrSKvKQ7IMpUCVibikPONIUK0u 6Qpgnyx+QnJdJv9Npx4Iq4H4JGMNjGNZaHaAFaDgHRAhIhleWyxkJ7gIOaIXoGuFDzKk RiUSaAa6zpo1gOvdIRvHOJP5JEPxvBOQ7BHz05iiGTc0YDGr/cZ09dFb5T72ZZh/TECy HbOTygrbw7dWPeERIDJ49fh2A7XoqA0IYXmrlsKhw/EP0dt1uWtfDZwty+IOcWe7jlkY N28nShWYTtOS43lInrJHV0eSenJ/70UQpgzviKicBS4F3hHmwNVwEi1Cx45yljN56mHX hw== Received: from aserp3020.oracle.com (aserp3020.oracle.com [141.146.126.70]) by userp2120.oracle.com with ESMTP id 2yub27925p-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 19 Mar 2020 16:01:15 +0000 Received: from pps.filterd (aserp3020.oracle.com [127.0.0.1]) by aserp3020.oracle.com (8.16.0.42/8.16.0.42) with SMTP id 02JFnqMD136226; Thu, 19 Mar 2020 16:01:14 GMT Received: from userv0121.oracle.com (userv0121.oracle.com [156.151.31.72]) by aserp3020.oracle.com with ESMTP id 2ys92mgbkm-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 19 Mar 2020 16:01:13 +0000 Received: from abhmp0016.oracle.com (abhmp0016.oracle.com [141.146.116.22]) by userv0121.oracle.com (8.14.4/8.13.8) with ESMTP id 02JG1AmM014111; Thu, 19 Mar 2020 16:01:11 GMT Received: from [10.39.245.129] (/10.39.245.129) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Thu, 19 Mar 2020 09:01:10 -0700 Subject: Re: [PATCH] xen/events: avoid NULL pointer dereference in evtchn_from_irq() To: Juergen Gross , xen-devel@lists.xenproject.org, linux-kernel@vger.kernel.org Cc: Stefano Stabellini , =?UTF-8?Q?Marek_Marczykowski-G=c3=b3recki?= , stable@vger.kernel.org References: <20200319071428.12115-1-jgross@suse.com> From: Boris Ostrovsky Message-ID: <1f8aab2c-dddc-494c-708d-85087c8d4e57@oracle.com> Date: Thu, 19 Mar 2020 12:01:05 -0400 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.4.1 MIME-Version: 1.0 In-Reply-To: <20200319071428.12115-1-jgross@suse.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9565 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 malwarescore=0 mlxlogscore=999 mlxscore=0 spamscore=0 bulkscore=0 adultscore=0 suspectscore=0 phishscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2003020000 definitions=main-2003190069 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9565 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 malwarescore=0 impostorscore=0 mlxlogscore=999 mlxscore=0 phishscore=0 adultscore=0 suspectscore=0 clxscore=1011 priorityscore=1501 lowpriorityscore=0 bulkscore=0 spamscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2003020000 definitions=main-2003190069 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 3/19/20 3:14 AM, Juergen Gross wrote: > There have been reports of races in evtchn_from_irq() where the info > pointer has been NULL. Do you have an example of how this race happens (and how moving kfree to rcu will help)? (I am mostly wondering whether we'd be masking a more serious problem) -boris