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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id E718FC4167D for ; Wed, 27 Apr 2022 15:54:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240667AbiD0P5z (ORCPT ); Wed, 27 Apr 2022 11:57:55 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55532 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240577AbiD0P5v (ORCPT ); Wed, 27 Apr 2022 11:57:51 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CC4D8737BD; Wed, 27 Apr 2022 08:54:26 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id DDAC8B82881; Wed, 27 Apr 2022 15:54:22 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7AC5BC385AC; Wed, 27 Apr 2022 15:54:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1651074861; bh=cCZFMNJ7sc4kval9MNFBp8yBF+FZbUz3Tw4iKsgYzLI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=U1ouTdQnremIxFpmyaboRGSRLQKNR1RgfsOhNKdsB4uAdq/5TL+n8+g/i1d5Ci1WP H2ajL4W1Wt/tqhIBfy9S5qhDXuWGndnHVGeynn04I4TSVdw2CmkcAI9++va1RC+H7g bOiBryLq+l6MqSvqcSBpYFcUO0lcdfRNmkQmEYhP6oph/OMxMD/Tuj1ixPmnLxst6B 0HWDi8r1JxY8HfbDDXo8hN3zr7tVfY66tSpaVU44WNs3/V6zvKeghoc9e4YYeYLPXL bE+e1MOwMg2e1dejpaZiF/yiShfnUak+tPUmNs6sNAY5zWgbROdIFdu9fTfwMH78a6 0FHKlbAa7+nwQ== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Paolo Bonzini , Sean Christopherson , Sasha Levin , tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org, kvm@vger.kernel.org Subject: [PATCH MANUALSEL 5.17 5/7] KVM: x86/mmu: avoid NULL-pointer dereference on page freeing bugs Date: Wed, 27 Apr 2022 11:54:01 -0400 Message-Id: <20220427155408.19352-5-sashal@kernel.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220427155408.19352-1-sashal@kernel.org> References: <20220427155408.19352-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Paolo Bonzini [ Upstream commit 9191b8f0745e63edf519e4a54a4aaae1d3d46fbd ] WARN and bail if KVM attempts to free a root that isn't backed by a shadow page. KVM allocates a bare page for "special" roots, e.g. when using PAE paging or shadowing 2/3/4-level page tables with 4/5-level, and so root_hpa will be valid but won't be backed by a shadow page. It's all too easy to blindly call mmu_free_root_page() on root_hpa, be nice and WARN instead of crashing KVM and possibly the kernel. Reviewed-by: Sean Christopherson Signed-off-by: Paolo Bonzini Signed-off-by: Sasha Levin --- arch/x86/kvm/mmu/mmu.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index 7f009ebb319a..e7cd16e1e0a0 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -3239,6 +3239,8 @@ static void mmu_free_root_page(struct kvm *kvm, hpa_t *root_hpa, return; sp = to_shadow_page(*root_hpa & PT64_BASE_ADDR_MASK); + if (WARN_ON(!sp)) + return; if (is_tdp_mmu_page(sp)) kvm_tdp_mmu_put_root(kvm, sp, false); -- 2.35.1