From nobody Sun Feb 8 23:25:24 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2638BEB64DD for ; Sat, 22 Jul 2023 01:24:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230384AbjGVBYH (ORCPT ); Fri, 21 Jul 2023 21:24:07 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37264 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231228AbjGVBX7 (ORCPT ); Fri, 21 Jul 2023 21:23:59 -0400 Received: from mail-yb1-xb49.google.com (mail-yb1-xb49.google.com [IPv6:2607:f8b0:4864:20::b49]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3840B35AD for ; Fri, 21 Jul 2023 18:23:58 -0700 (PDT) Received: by mail-yb1-xb49.google.com with SMTP id 3f1490d57ef6-cab7304dcccso2457603276.3 for ; Fri, 21 Jul 2023 18:23:58 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20221208; t=1689989037; x=1690593837; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:reply-to:from:to:cc:subject:date:message-id:reply-to; bh=K8g8ylIBioHABO4UYnvq+eRAgeeK2kAPLMh05XoHYU4=; b=d9n714xKJqMwcsAZMI0NHTCtMswGC8ES6vvzsYorFNt0M9xXUeBRyv2a9UkMH2SDBb 1ScznqmzIh4kjUyE1rSGMt/RSAjUOgBLjmGeokgwc60pdNX308+hKXWH1xXe2eJ1E7UE 05Os0QeMBsYL+KYrO61vzAUcL8pSdwb+96Z18F1kECGsA94JjKWTeYHXZFmAJjnJ1zha vpdW1oLjoY/H5htKcV2jS7OfuDX/CAAY8O0JZDKKDltJ//M2/x0m9xTroHtPNR5sFrHa 9EfyrhBnD0vt7qK+t8Y0oFu8yMInPvL09a53JrtWtYnKRNKlsMgf/sCN6zvwRwW95iyM scGQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1689989037; x=1690593837; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:reply-to:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=K8g8ylIBioHABO4UYnvq+eRAgeeK2kAPLMh05XoHYU4=; b=Kqk9lh2PGzgwMwRtswRqNhkDxZ8DqHm2LcE4xo0eDQUKUEZgCFg4aZGYqkiRWH9vUy /ki1HMmjV87ge/7zUuhB754iyluz60bFoMjRgQihl+Qqv2TqQq6CFN62ZNtYH1Jp/S6J tORReMJPInOvhHNpm0F7cGNlYQjVNyUklD+XiN0tLHUFOpL6H0KZIhXQAOFKcW8ha1K2 hi8K5YIpH5gyetH9E0CM2rNZC3LRzJ33OCRbeDHp6CAVgpOQoyxr5uI5R1+AXGpDhSnU s2DRQXVnN1Rwbu+JhAOblxqrzT9USig8TTusg+vdLOHp9OdBzNkNaDP9FG7uBRhOP8fp puWA== X-Gm-Message-State: ABy/qLYPqmtqMIxn2T5ixtZxCWyT4Jh6RVM74dDNIop/LgBIP4ZmEI0V ykquYx6yQlU3FynPfrAkAFGEYAeVX3o= X-Google-Smtp-Source: APBJJlF+A0iIM85uIonjtFc0LBUEjOC6Z7bNRybAKOxeB2niAfBIolVS8Vuvx1nG9NWSwW1CFVKCGR0Ae6s= X-Received: from zagreus.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:5c37]) (user=seanjc job=sendgmr) by 2002:a25:245:0:b0:d06:cbd:1f3e with SMTP id 66-20020a250245000000b00d060cbd1f3emr13920ybc.3.1689989037474; Fri, 21 Jul 2023 18:23:57 -0700 (PDT) Reply-To: Sean Christopherson Date: Fri, 21 Jul 2023 18:23:48 -0700 In-Reply-To: <20230722012350.2371049-1-seanjc@google.com> Mime-Version: 1.0 References: <20230722012350.2371049-1-seanjc@google.com> X-Mailer: git-send-email 2.41.0.487.g6d72f3e995-goog Message-ID: <20230722012350.2371049-4-seanjc@google.com> Subject: [PATCH 3/5] KVM: x86/mmu: Harden TDP MMU iteration against root w/o shadow page From: Sean Christopherson To: Sean Christopherson , Paolo Bonzini Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Reima Ishii Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Explicitly check that tdp_iter_start() is handed a valid shadow page to harden KVM against bugs where Opportunistically stop the TDP MMU iteration instead of continuing on with garbage if the incoming root is bogus. Attempting to walk a garbage root is more likely to caused major problems than doing nothing. Signed-off-by: Sean Christopherson --- arch/x86/kvm/mmu/tdp_iter.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-) diff --git a/arch/x86/kvm/mmu/tdp_iter.c b/arch/x86/kvm/mmu/tdp_iter.c index d2eb0d4f8710..bd30ebfb2f2c 100644 --- a/arch/x86/kvm/mmu/tdp_iter.c +++ b/arch/x86/kvm/mmu/tdp_iter.c @@ -39,13 +39,14 @@ void tdp_iter_restart(struct tdp_iter *iter) void tdp_iter_start(struct tdp_iter *iter, struct kvm_mmu_page *root, int min_level, gfn_t next_last_level_gfn) { - int root_level =3D root->role.level; - - WARN_ON(root_level < 1); - WARN_ON(root_level > PT64_ROOT_MAX_LEVEL); + if (WARN_ON_ONCE(!root || (root->role.level < 1) || + (root->role.level > PT64_ROOT_MAX_LEVEL))) { + iter->valid =3D false; + return; + } =20 iter->next_last_level_gfn =3D next_last_level_gfn; - iter->root_level =3D root_level; + iter->root_level =3D root->role.level; iter->min_level =3D min_level; iter->pt_path[iter->root_level - 1] =3D (tdp_ptep_t)root->spt; iter->as_id =3D kvm_mmu_page_as_id(root); --=20 2.41.0.487.g6d72f3e995-goog