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=-5.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham 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 D416BCA9EA0 for ; Mon, 4 Nov 2019 11:19:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id AFD4C21D7D for ; Mon, 4 Nov 2019 11:19:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728698AbfKDLTk (ORCPT ); Mon, 4 Nov 2019 06:19:40 -0500 Received: from mx1.redhat.com ([209.132.183.28]:48088 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727976AbfKDLTk (ORCPT ); Mon, 4 Nov 2019 06:19:40 -0500 Received: from mail-wr1-f72.google.com (mail-wr1-f72.google.com [209.85.221.72]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id A24B486663 for ; Mon, 4 Nov 2019 11:19:39 +0000 (UTC) Received: by mail-wr1-f72.google.com with SMTP id v6so975875wrm.18 for ; Mon, 04 Nov 2019 03:19:39 -0800 (PST) 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:openpgp:message-id :date:user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=IyB/9FjVy0L8r3UgW28zHK/5BLov7tJmvoQB43XUc5U=; b=T6rYl+k6CTvMfEaWIjoouQvkBNZo1PU0a5n5lupASqchCog9rONLZfGsJkgCyYACRJ 1Uk2n84t0UGZ4U/OssYY0yfEeDrcVuD0lVuu8m+FwaxgzzsoQkiMUMEIxWh2fx71Ek91 MSUCwzfoZjoxI3vckBz0YlcYIXip1bFjBkZQeY/fSCXVDD0aTXllLIer6GflLEa4lLPo Ek4vcxZLKJy6CpsJO65Xw/4axa8s017vXTZBUXH8i7VtvczQL4dMDe8WOLMlpSu2sx43 tHBZEf3b3boyssX5HrDPihmydebMHaqcOp+ONB8gPKfCyuO8cGJs1FQxlrPLuI7HZnCd Akcw== X-Gm-Message-State: APjAAAVc49gdBJChrdAOmubnfqC9QGAzYHvqwmeQAlI13Y3aHMwI4PsL CL+aB9vZ6K/FWSLTzNqXRg01iiWN8CRkD2uu4UgXZrGFzsYa9V5uxPv/J5RfuaXtYaHuwhsC6oI vrj0AyjrhLjE9LYjqZPgtPdgU X-Received: by 2002:adf:cf11:: with SMTP id o17mr22563005wrj.284.1572866378274; Mon, 04 Nov 2019 03:19:38 -0800 (PST) X-Google-Smtp-Source: APXvYqwVKUPV8W60run1lYhxWK79IIU0DtaJkMmOqyowGnPFh+KCscVP6nwt1b1fryS4H5d9uC+blA== X-Received: by 2002:adf:cf11:: with SMTP id o17mr22562979wrj.284.1572866377969; Mon, 04 Nov 2019 03:19:37 -0800 (PST) Received: from ?IPv6:2001:b07:6468:f312:4051:461:136e:3f74? ([2001:b07:6468:f312:4051:461:136e:3f74]) by smtp.gmail.com with ESMTPSA id a206sm23814056wmf.15.2019.11.04.03.19.37 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 04 Nov 2019 03:19:37 -0800 (PST) Subject: Re: [PATCH 1/2] KVM: Fix NULL-ptr defer after kvm_create_vm fails To: Wanpeng Li , linux-kernel@vger.kernel.org, kvm@vger.kernel.org Cc: =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= , Sean Christopherson , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel References: <1572848879-21011-1-git-send-email-wanpengli@tencent.com> From: Paolo Bonzini Openpgp: preference=signencrypt Message-ID: <6a3217bc-cc01-38db-f994-b501110b14bf@redhat.com> Date: Mon, 4 Nov 2019 12:19:36 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <1572848879-21011-1-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 04/11/19 07:27, Wanpeng Li wrote: > Commit 9121923c457d ("kvm: Allocate memslots and buses before calling kvm_arch_init_vm") > moves memslots and buses allocations around, however, if kvm->srcu/irq_srcu fails > initialization, NULL will be returned instead of error code, NULL will not be intercepted > in kvm_dev_ioctl_create_vm() and be deferenced by kvm_coalesced_mmio_init(), this patch > fixes it. This is not enough, as syzkaller also reported an incorrect synchronize_srcu that was also reported by syzkaller: wait_for_completion+0x29c/0x440 kernel/sched/completion.c:136 __synchronize_srcu+0x197/0x250 kernel/rcu/srcutree.c:921 synchronize_srcu_expedited kernel/rcu/srcutree.c:946 [inline] synchronize_srcu+0x239/0x3e8 kernel/rcu/srcutree.c:997 kvm_page_track_unregister_notifier+0xe7/0x130 arch/x86/kvm/page_track.c:212 kvm_mmu_uninit_vm+0x1e/0x30 arch/x86/kvm/mmu.c:5828 kvm_arch_destroy_vm+0x4a2/0x5f0 arch/x86/kvm/x86.c:9579 kvm_create_vm arch/x86/kvm/../../../virt/kvm/kvm_main.c:702 [inline] I'm thinking of something like this (not tested yet): diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index d6f0696d98ef..e22ff63e5b1a 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -645,6 +645,11 @@ static struct kvm *kvm_create_vm(unsigned long type) BUILD_BUG_ON(KVM_MEM_SLOTS_NUM > SHRT_MAX); + if (init_srcu_struct(&kvm->srcu)) + goto out_err_no_srcu; + if (init_srcu_struct(&kvm->irq_srcu)) + goto out_err_no_irq_srcu; + for (i = 0; i < KVM_ADDRESS_SPACE_NUM; i++) { struct kvm_memslots *slots = kvm_alloc_memslots(); @@ -675,11 +680,6 @@ static struct kvm *kvm_create_vm(unsigned long type) INIT_HLIST_HEAD(&kvm->irq_ack_notifier_list); #endif - if (init_srcu_struct(&kvm->srcu)) - goto out_err_no_srcu; - if (init_srcu_struct(&kvm->irq_srcu)) - goto out_err_no_irq_srcu; - r = kvm_init_mmu_notifier(kvm); if (r) goto out_err; @@ -693,10 +693,6 @@ static struct kvm *kvm_create_vm(unsigned long type) return kvm; out_err: - cleanup_srcu_struct(&kvm->irq_srcu); -out_err_no_irq_srcu: - cleanup_srcu_struct(&kvm->srcu); -out_err_no_srcu: hardware_disable_all(); out_err_no_disable: kvm_arch_destroy_vm(kvm); @@ -706,6 +702,10 @@ static struct kvm *kvm_create_vm(unsigned long type) kfree(kvm_get_bus(kvm, i)); for (i = 0; i < KVM_ADDRESS_SPACE_NUM; i++) kvm_free_memslots(kvm, __kvm_memslots(kvm, i)); + cleanup_srcu_struct(&kvm->irq_srcu); +out_err_no_irq_srcu: + cleanup_srcu_struct(&kvm->srcu); +out_err_no_srcu: kvm_arch_free_vm(kvm); mmdrop(current->mm); return ERR_PTR(r); Paolo