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=-16.5 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,USER_AGENT_GIT 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 40360C49EA4 for ; Mon, 21 Jun 2021 16:25:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 26E12613C2 for ; Mon, 21 Jun 2021 16:25:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232035AbhFUQ2J (ORCPT ); Mon, 21 Jun 2021 12:28:09 -0400 Received: from mail.kernel.org ([198.145.29.99]:48560 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231162AbhFUQ0X (ORCPT ); Mon, 21 Jun 2021 12:26:23 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id D38C761164; Mon, 21 Jun 2021 16:22:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1624292540; bh=hiPF+RosvCLDuD/Y/PuMlF+/+Zt7YBkW3724fIap3sk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=k90br6+Gk3ROt8hUfxZnL4kEwaLMvxqmEX8xSqkNgFnazNKsYOIqmbc2VgPAM6GzN s4fdcjrpDBlCRDNdrrihcSkGSkVhttCo3pI7eMMhnfGvlRHTlspF6VytHHC20me+XG rN08I5ulY/JmzvSCZh5B9VcM4jGbCY7r+Im6+Z7A= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Jim Mattson , syzbot , Paolo Bonzini , Sasha Levin Subject: [PATCH 5.10 010/146] kvm: LAPIC: Restore guard to prevent illegal APIC register access Date: Mon, 21 Jun 2021 18:14:00 +0200 Message-Id: <20210621154911.603988175@linuxfoundation.org> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210621154911.244649123@linuxfoundation.org> References: <20210621154911.244649123@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Jim Mattson [ Upstream commit 218bf772bddd221489c38dde6ef8e917131161f6 ] Per the SDM, "any access that touches bytes 4 through 15 of an APIC register may cause undefined behavior and must not be executed." Worse, such an access in kvm_lapic_reg_read can result in a leak of kernel stack contents. Prior to commit 01402cf81051 ("kvm: LAPIC: write down valid APIC registers"), such an access was explicitly disallowed. Restore the guard that was removed in that commit. Fixes: 01402cf81051 ("kvm: LAPIC: write down valid APIC registers") Signed-off-by: Jim Mattson Reported-by: syzbot Message-Id: <20210602205224.3189316-1-jmattson@google.com> Signed-off-by: Paolo Bonzini Signed-off-by: Sasha Levin --- arch/x86/kvm/lapic.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c index 5759eb075d2f..677d21082454 100644 --- a/arch/x86/kvm/lapic.c +++ b/arch/x86/kvm/lapic.c @@ -1405,6 +1405,9 @@ int kvm_lapic_reg_read(struct kvm_lapic *apic, u32 offset, int len, if (!apic_x2apic_mode(apic)) valid_reg_mask |= APIC_REG_MASK(APIC_ARBPRI); + if (alignment + len > 4) + return 1; + if (offset > 0x3f0 || !(valid_reg_mask & APIC_REG_MASK(offset))) return 1; -- 2.30.2