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=-8.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 BD470C433E2 for ; Mon, 29 Jun 2020 19:06:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9EBA6206A5 for ; Mon, 29 Jun 2020 19:06:17 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="Fce1K0Oh" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730735AbgF2TGP (ORCPT ); Mon, 29 Jun 2020 15:06:15 -0400 Received: from us-smtp-1.mimecast.com ([207.211.31.81]:55375 "EHLO us-smtp-delivery-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1730037AbgF2TGN (ORCPT ); Mon, 29 Jun 2020 15:06:13 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1593457572; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=wiA60jnjSVk1PN6FvCwFOWuyAKPOYAY44lt2HUcQNf4=; b=Fce1K0OhI4n8GXXkr71jHl24wl4Cn5c1UK2uzi7eDRUgQozU7BMbOCFVNgH2BfebMgmcT7 5THjliWzZixzSxbfbn+ppcPeVR/XnnYlYz1ufDx2dB/ZlhzK6mmI29VdKFzsKcMxri9Vil VVLr+Ku+YqyLsuJJzxTplIZdsJiPEP8= Received: from mail-wr1-f69.google.com (mail-wr1-f69.google.com [209.85.221.69]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-217-WF7REQIJOxiSNRrVrGysAw-1; Mon, 29 Jun 2020 11:03:44 -0400 X-MC-Unique: WF7REQIJOxiSNRrVrGysAw-1 Received: by mail-wr1-f69.google.com with SMTP id y13so16666132wrp.13 for ; Mon, 29 Jun 2020 08:03:44 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=wiA60jnjSVk1PN6FvCwFOWuyAKPOYAY44lt2HUcQNf4=; b=bv84YorrWpAmSkVEounLH8RrzzWA/LiW3gfz7BAym/QWhiv33wMZge7kj38VH31F94 SXI8gP9vaO6Uw0eR9SGoXokXqT0Ugu2gvF3q+zsKeWYeMgJ3ynvluJcCxx9/OC54Hqa0 QlZpEQwkM5/EtLrR0yqf6f5a+/aucArPWDUY3zI24gXaMwKu0lBqFrxpvNBnq6ebC8oC 7d/dnMGbVXZJ/M/BNqiHyr3hmNSxWH6LykTHN5zi94VioAvB+kRJWm/IOs2D0dVS9Q+Y q3fx/IeS21MMp4sGpjhnFyGESP0lVARPfDJxQY/c+ZMQx8hunohV7oNpcAgDfgZ6Mgty qvJw== X-Gm-Message-State: AOAM531kygnbmiZ4TKJmm3ClPPKq4GxHPCoMfITPWAgGmvnvDTLD+Npc c6R0e6KUb1nAwltoqQTutAmXtE+dMWYgTxii4ziIIqlGCXhUqWFvHb97q30AdPl/Ngmo2GErkiX bI7LvsMa0Eh8JYOi+9QaV6iBr X-Received: by 2002:a7b:c185:: with SMTP id y5mr17739374wmi.85.1593443023634; Mon, 29 Jun 2020 08:03:43 -0700 (PDT) X-Google-Smtp-Source: ABdhPJyfWzhvzup1XHO1uAaeVJMlYTx2UJCwm1ZI0mJJ7N8UF2kln9C5WXC5FIAYwAJfdIO20eLgbA== X-Received: by 2002:a7b:c185:: with SMTP id y5mr17739339wmi.85.1593443023215; Mon, 29 Jun 2020 08:03:43 -0700 (PDT) Received: from ?IPv6:2001:b07:6468:f312:b0e5:c632:a580:8b9a? ([2001:b07:6468:f312:b0e5:c632:a580:8b9a]) by smtp.gmail.com with ESMTPSA id a126sm63300wme.28.2020.06.29.08.03.42 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 29 Jun 2020 08:03:42 -0700 (PDT) Subject: Re: [PATCH] KVM: X86: Fix async pf caused null-ptr-deref To: Wanpeng Li , linux-kernel@vger.kernel.org, kvm@vger.kernel.org Cc: Sean Christopherson , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel References: <1593426391-8231-1-git-send-email-wanpengli@tencent.com> From: Paolo Bonzini Message-ID: <60b8326d-3979-6218-4a41-79c86ffab3bd@redhat.com> Date: Mon, 29 Jun 2020 17:03:41 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.6.0 MIME-Version: 1.0 In-Reply-To: <1593426391-8231-1-git-send-email-wanpengli@tencent.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 29/06/20 12:26, Wanpeng Li wrote: > From: Wanpeng Li > > Syzbot reported that: > > CPU: 1 PID: 6780 Comm: syz-executor153 Not tainted 5.7.0-syzkaller #0 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 > RIP: 0010:__apic_accept_irq+0x46/0xb80 > Call Trace: > kvm_arch_async_page_present+0x7de/0x9e0 > kvm_check_async_pf_completion+0x18d/0x400 > kvm_arch_vcpu_ioctl_run+0x18bf/0x69f0 > kvm_vcpu_ioctl+0x46a/0xe20 > ksys_ioctl+0x11a/0x180 > __x64_sys_ioctl+0x6f/0xb0 > do_syscall_64+0xf6/0x7d0 > entry_SYSCALL_64_after_hwframe+0x49/0xb3 > > The testcase enables APF mechanism in MSR_KVM_ASYNC_PF_EN with ASYNC_PF_INT > enabled w/o setting MSR_KVM_ASYNC_PF_INT before, what's worse, interrupt > based APF 'page ready' event delivery depends on in kernel lapic, however, > we didn't bail out when lapic is not in kernel during guest setting > MSR_KVM_ASYNC_PF_EN which causes the null-ptr-deref in host later. > This patch fixes it. > > Reported-by: syzbot+1bf777dfdde86d64b89b@syzkaller.appspotmail.com > Fixes: 2635b5c4a0 (KVM: x86: interrupt based APF 'page ready' event delivery) > Signed-off-by: Wanpeng Li > --- > arch/x86/kvm/x86.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index 00c88c2..1c0b4f5 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -2693,6 +2693,9 @@ static int kvm_pv_enable_async_pf(struct kvm_vcpu *vcpu, u64 data) > if (data & 0x30) > return 1; > > + if (!lapic_in_kernel(vcpu)) > + return 1; > + > vcpu->arch.apf.msr_en_val = data; > > if (!kvm_pv_async_pf_enabled(vcpu)) { > Queued, thanks. Paolo