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=-6.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=ham 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 422EEC3A59F for ; Thu, 29 Aug 2019 10:54:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1485123405 for ; Thu, 29 Aug 2019 10:54:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728802AbfH2KyH (ORCPT ); Thu, 29 Aug 2019 06:54:07 -0400 Received: from mx1.redhat.com ([209.132.183.28]:3732 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727075AbfH2KyG (ORCPT ); Thu, 29 Aug 2019 06:54:06 -0400 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id BE03C3C93E; Thu, 29 Aug 2019 10:54:05 +0000 (UTC) Received: from thuth.com (ovpn-116-53.ams2.redhat.com [10.36.116.53]) by smtp.corp.redhat.com (Postfix) with ESMTP id 676CD5C1D6; Thu, 29 Aug 2019 10:54:00 +0000 (UTC) From: Thomas Huth To: Christian Borntraeger , Janosch Frank , kvm@vger.kernel.org Cc: David Hildenbrand , Cornelia Huck , Heiko Carstens , Vasily Gorbik , linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH] KVM: s390: Test for bad access register at the start of S390_MEM_OP Date: Thu, 29 Aug 2019 12:53:56 +0200 Message-Id: <20190829105356.27805-1-thuth@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.39]); Thu, 29 Aug 2019 10:54:05 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. Signed-off-by: Thomas Huth --- 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..725690853cbd 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) return -EINVAL; if (mop->size > MEM_OP_MAX_SIZE) -- 2.18.1