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=-3.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 CEC91C433E1 for ; Wed, 20 May 2020 14:23:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AE10F205CB for ; Wed, 20 May 2020 14:23:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728073AbgETOXf (ORCPT ); Wed, 20 May 2020 10:23:35 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:33124 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727052AbgETOW2 (ORCPT ); Wed, 20 May 2020 10:22:28 -0400 Received: from [192.168.4.242] (helo=deadeye) by shadbolt.decadent.org.uk with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.89) (envelope-from ) id 1jbPbz-00037e-Vx; Wed, 20 May 2020 15:22:24 +0100 Received: from ben by deadeye with local (Exim 4.93) (envelope-from ) id 1jbPbx-007DVZ-8z; Wed, 20 May 2020 15:22:21 +0100 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, Denis Kirjanov , "Marios Pomonis" , "Nick Finco" , "Jim Mattson" , "Paolo Bonzini" , "Andrew Honig" Date: Wed, 20 May 2020 15:14:51 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) X-Patchwork-Hint: ignore Subject: [PATCH 3.16 83/99] KVM: x86: Protect DR-based index computations from Spectre-v1/L1TF attacks In-Reply-To: X-SA-Exim-Connect-IP: 192.168.4.242 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16.84-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Marios Pomonis commit ea740059ecb37807ba47b84b33d1447435a8d868 upstream. This fixes a Spectre-v1/L1TF vulnerability in __kvm_set_dr() and kvm_get_dr(). Both kvm_get_dr() and kvm_set_dr() (a wrapper of __kvm_set_dr()) are exported symbols so KVM should tream them conservatively from a security perspective. Fixes: 020df0794f57 ("KVM: move DR register access handling into generic code") Signed-off-by: Nick Finco Signed-off-by: Marios Pomonis Reviewed-by: Andrew Honig Reviewed-by: Jim Mattson Signed-off-by: Paolo Bonzini Signed-off-by: Ben Hutchings --- arch/x86/kvm/x86.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -801,9 +801,11 @@ static void kvm_update_dr7(struct kvm_vc static int __kvm_set_dr(struct kvm_vcpu *vcpu, int dr, unsigned long val) { + size_t size = ARRAY_SIZE(vcpu->arch.db); + switch (dr) { case 0 ... 3: - vcpu->arch.db[dr] = val; + vcpu->arch.db[array_index_nospec(dr, size)] = val; if (!(vcpu->guest_debug & KVM_GUESTDBG_USE_HW_BP)) vcpu->arch.eff_db[dr] = val; break; @@ -848,9 +850,11 @@ EXPORT_SYMBOL_GPL(kvm_set_dr); static int _kvm_get_dr(struct kvm_vcpu *vcpu, int dr, unsigned long *val) { + size_t size = ARRAY_SIZE(vcpu->arch.db); + switch (dr) { case 0 ... 3: - *val = vcpu->arch.db[dr]; + *val = vcpu->arch.db[array_index_nospec(dr, size)]; break; case 4: if (kvm_read_cr4_bits(vcpu, X86_CR4_DE))