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=-8.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=unavailable 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 23FAAC3A5A2 for ; Tue, 10 Sep 2019 13:16:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E879C2084D for ; Tue, 10 Sep 2019 13:16:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731095AbfIJNQ1 (ORCPT ); Tue, 10 Sep 2019 09:16:27 -0400 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:63670 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731068AbfIJNQ0 (ORCPT ); Tue, 10 Sep 2019 09:16:26 -0400 Received: from pps.filterd (m0098396.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.27/8.16.0.27) with SMTP id x8ADG1Vn049698 for ; Tue, 10 Sep 2019 09:16:25 -0400 Received: from e06smtp04.uk.ibm.com (e06smtp04.uk.ibm.com [195.75.94.100]) by mx0a-001b2d01.pphosted.com with ESMTP id 2ux9w4e8nf-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Tue, 10 Sep 2019 09:16:20 -0400 Received: from localhost by e06smtp04.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! 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Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Tue, 10 Sep 2019 14:15:41 +0100 Received: from d06av25.portsmouth.uk.ibm.com (d06av25.portsmouth.uk.ibm.com [9.149.105.61]) by b06cxnps4074.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id x8ADFdRv53149792 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 10 Sep 2019 13:15:39 GMT Received: from d06av25.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 7474711C054; Tue, 10 Sep 2019 13:15:39 +0000 (GMT) Received: from d06av25.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 0D8BB11C05C; Tue, 10 Sep 2019 13:15:39 +0000 (GMT) Received: from oc7455500831.ibm.com (unknown [9.152.224.184]) by d06av25.portsmouth.uk.ibm.com (Postfix) with ESMTP; Tue, 10 Sep 2019 13:15:38 +0000 (GMT) Subject: Re: [PATCH] KVM: s390: kvm_s390_vm_start_migration: check dirty_bitmap before using it as target for memset() To: Igor Mammedov , linux-kernel@vger.kernel.org Cc: david@redhat.com, cohuck@redhat.com, frankja@linux.ibm.com, heiko.carstens@de.ibm.com, gor@linux.ibm.com, imbrenda@linux.ibm.com, linux-s390@vger.kernel.org, kvm@vger.kernel.org, stable@vger.kernel.org References: <20190910130215.23647-1-imammedo@redhat.com> From: Christian Borntraeger Openpgp: preference=signencrypt Autocrypt: addr=borntraeger@de.ibm.com; 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Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <20190910130215.23647-1-imammedo@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 x-cbid: 19091013-0016-0000-0000-000002A981E1 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 19091013-0017-0000-0000-0000330A0917 Message-Id: X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-09-10_09:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=874 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1906280000 definitions=main-1909100129 Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On 10.09.19 15:02, Igor Mammedov wrote: > If userspace doesn't set KVM_MEM_LOG_DIRTY_PAGES on memslot before calling > kvm_s390_vm_start_migration(), kernel will oops with: > > Unable to handle kernel pointer dereference in virtual kernel address space > Failing address: 0000000000000000 TEID: 0000000000000483 > Fault in home space mode while using kernel ASCE. > AS:0000000002a2000b R2:00000001bff8c00b R3:00000001bff88007 S:00000001bff91000 P:000000000000003d > Oops: 0004 ilc:2 [#1] SMP > ... > Call Trace: > ([<001fffff804ec552>] kvm_s390_vm_set_attr+0x347a/0x3828 [kvm]) > [<001fffff804ecfc0>] kvm_arch_vm_ioctl+0x6c0/0x1998 [kvm] > [<001fffff804b67e4>] kvm_vm_ioctl+0x51c/0x11a8 [kvm] > [<00000000008ba572>] do_vfs_ioctl+0x1d2/0xe58 > [<00000000008bb284>] ksys_ioctl+0x8c/0xb8 > [<00000000008bb2e2>] sys_ioctl+0x32/0x40 > [<000000000175552c>] system_call+0x2b8/0x2d8 > INFO: lockdep is turned off. > Last Breaking-Event-Address: > [<0000000000dbaf60>] __memset+0xc/0xa0 > > due to ms->dirty_bitmap being NULL, which might crash the host. > > Make sure that ms->dirty_bitmap is set before using it or > print a warning and return -ENIVAL otherwise. > > Fixes: afdad61615cc ("KVM: s390: Fix storage attributes migration with memory slots") > Signed-off-by: Igor Mammedov > --- > Cc: stable@vger.kernel.org # v4.19+ Reviewed-by: Christian Borntraeger It also matches Documentation/virt/kvm/devices/vm.txt which already allows -EINVAL. > > v2: > - drop WARN() > > arch/s390/kvm/kvm-s390.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c > index f329dcb3f44c..2a40cd3e40b4 100644 > --- a/arch/s390/kvm/kvm-s390.c > +++ b/arch/s390/kvm/kvm-s390.c > @@ -1018,6 +1018,8 @@ static int kvm_s390_vm_start_migration(struct kvm *kvm) > /* mark all the pages in active slots as dirty */ > for (slotnr = 0; slotnr < slots->used_slots; slotnr++) { > ms = slots->memslots + slotnr; > + if (!ms->dirty_bitmap) > + return -EINVAL; > /* > * The second half of the bitmap is only used on x86, > * and would be wasted otherwise, so we put it to good >