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=-8.3 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 E78A7C3A59F for ; Thu, 29 Aug 2019 13:40:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B7B022339E for ; Thu, 29 Aug 2019 13:40:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727594AbfH2Nk6 (ORCPT ); Thu, 29 Aug 2019 09:40:58 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:62582 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1727069AbfH2Nk6 (ORCPT ); Thu, 29 Aug 2019 09:40:58 -0400 Received: from pps.filterd (m0098419.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.27/8.16.0.27) with SMTP id x7TDedoD079186 for ; Thu, 29 Aug 2019 09:40:55 -0400 Received: from e06smtp01.uk.ibm.com (e06smtp01.uk.ibm.com [195.75.94.97]) by mx0b-001b2d01.pphosted.com with ESMTP id 2upcxepunu-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Thu, 29 Aug 2019 09:40:47 -0400 Received: from localhost by e06smtp01.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) Thu, 29 Aug 2019 14:38:36 +0100 Received: from d06av24.portsmouth.uk.ibm.com (d06av24.portsmouth.uk.ibm.com [9.149.105.60]) by b06cxnps4075.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id x7TDcZB349283106 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 29 Aug 2019 13:38:35 GMT Received: from d06av24.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id E96CA42042; Thu, 29 Aug 2019 13:38:34 +0000 (GMT) Received: from d06av24.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 95CB94203F; Thu, 29 Aug 2019 13:38:34 +0000 (GMT) Received: from oc7455500831.ibm.com (unknown [9.152.224.51]) by d06av24.portsmouth.uk.ibm.com (Postfix) with ESMTP; Thu, 29 Aug 2019 13:38:34 +0000 (GMT) Subject: Re: [PATCH v2] KVM: s390: Test for bad access register and size at the start of S390_MEM_OP To: Cornelia Huck , Thomas Huth Cc: Janosch Frank , kvm@vger.kernel.org, David Hildenbrand , Heiko Carstens , Vasily Gorbik , linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org References: <20190829122517.31042-1-thuth@redhat.com> <20190829144013.322edb0a.cohuck@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: <20190829144013.322edb0a.cohuck@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 x-cbid: 19082913-4275-0000-0000-0000035EB34D X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 19082913-4276-0000-0000-00003870EAD9 Message-Id: X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-08-29_06:,, 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=853 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1906280000 definitions=main-1908290150 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 29.08.19 14:40, Cornelia Huck wrote: > On Thu, 29 Aug 2019 14:25:17 +0200 > Thomas Huth wrote: > >> If the KVM_S390_MEM_OP ioctl is called with an access register >= 16, >> then there is certainly a bug in the calling userspace application. >> We check for wrong access registers, but only if the vCPU was already >> in the access register mode before (i.e. the SIE block has recorded >> it). The check is also buried somewhere deep in the calling chain (in >> the function ar_translation()), so this is somewhat hard to find. >> >> It's better to always report an error to the userspace in case this >> field is set wrong, and it's safer in the KVM code if we block wrong >> values here early instead of relying on a check somewhere deep down >> the calling chain, so let's add another check to kvm_s390_guest_mem_op() >> directly. >> >> We also should check that the "size" is non-zero here (thanks to Janosch >> Frank for the hint!). If we do not check the size, we could call vmalloc() >> with this 0 value, and this will cause a kernel warning. >> >> Signed-off-by: Thomas Huth I will add cc stable. Thanks applied. >> --- >> v2: Check mop->size to be non-zero >> >> arch/s390/kvm/kvm-s390.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c >> index f329dcb3f44c..49d7722229ae 100644 >> --- a/arch/s390/kvm/kvm-s390.c >> +++ b/arch/s390/kvm/kvm-s390.c >> @@ -4255,7 +4255,7 @@ static long kvm_s390_guest_mem_op(struct kvm_vcpu *vcpu, >> const u64 supported_flags = KVM_S390_MEMOP_F_INJECT_EXCEPTION >> | KVM_S390_MEMOP_F_CHECK_ONLY; >> >> - if (mop->flags & ~supported_flags) >> + if (mop->flags & ~supported_flags || mop->ar >= NUM_ACRS || !mop->size) >> return -EINVAL; >> >> if (mop->size > MEM_OP_MAX_SIZE) > > Reviewed-by: Cornelia Huck >