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=-6.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 ED3F7C76195 for ; Thu, 18 Jul 2019 03:15:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C39662077C for ; Thu, 18 Jul 2019 03:15:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1563419720; bh=RqHs4PD78dqw4xd7ttlwOYA6we00lDzzgKgXO/uJ2ME=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=QjU5WjaVNiv/7Ixp5nICjr5PApBZBow3Oc0urTPMI0siN84GpzwgH6vhtX80qAfdV m3dK1LDDqbOwlPTeyb2esfA4ILpQ1QLNc0p4lKY1HwSZjXu7io604uEhcYLqh+KuVF 08AUzilvuIdtIkFjsq7dfAH9TGXAPBVbq0IucaT0= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2391994AbfGRDPS (ORCPT ); Wed, 17 Jul 2019 23:15:18 -0400 Received: from mail.kernel.org ([198.145.29.99]:52244 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2391985AbfGRDPS (ORCPT ); Wed, 17 Jul 2019 23:15:18 -0400 Received: from localhost (115.42.148.210.bf.2iij.net [210.148.42.115]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 0189D21849; Thu, 18 Jul 2019 03:15:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1563419717; bh=RqHs4PD78dqw4xd7ttlwOYA6we00lDzzgKgXO/uJ2ME=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Eq8QFYq6S9xQNOgP5Dl4sKunvUd+MwmmET8eJ01WzV73DSC7qlUMWiBXlxfZBpOAo r8fpFtTS032MMRJcYYMNLUsFOza5BHh8EleuO6FRlVy4Xf/XJNCvAC1o7CWSHrTjMU tD1HzKIvrxa2I3gH+plmyZmfKtgEMeK+qmzZefOk= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Dmitry Vyukov , Paolo Bonzini , =?UTF-8?q?Radim=20Kr=C4=8Dm=C3=A1=C5=99?= , Zubin Mithra Subject: [PATCH 4.4 40/40] KVM: x86: protect KVM_CREATE_PIT/KVM_CREATE_PIT2 with kvm->lock Date: Thu, 18 Jul 2019 12:02:36 +0900 Message-Id: <20190718030050.616694335@linuxfoundation.org> X-Mailer: git-send-email 2.22.0 In-Reply-To: <20190718030039.676518610@linuxfoundation.org> References: <20190718030039.676518610@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Paolo Bonzini commit 250715a6171a076748be8ab88b274e72f0cfb435 upstream. The syzkaller folks reported a NULL pointer dereference that seems to be cause by a race between KVM_CREATE_IRQCHIP and KVM_CREATE_PIT2. The former takes kvm->lock (except when registering the devices, which needs kvm->slots_lock); the latter takes kvm->slots_lock only. Change KVM_CREATE_PIT2 to follow the same model as KVM_CREATE_IRQCHIP. Testcase: #include #include #include #include #include #include #include #include #include long r[23]; void* thr1(void* arg) { struct kvm_pit_config pitcfg = { .flags = 4 }; switch ((long)arg) { case 0: r[2] = open("/dev/kvm", O_RDONLY|O_ASYNC); break; case 1: r[3] = ioctl(r[2], KVM_CREATE_VM, 0); break; case 2: r[4] = ioctl(r[3], KVM_CREATE_IRQCHIP, 0); break; case 3: r[22] = ioctl(r[3], KVM_CREATE_PIT2, &pitcfg); break; } return 0; } int main(int argc, char **argv) { long i; pthread_t th[4]; memset(r, -1, sizeof(r)); for (i = 0; i < 4; i++) { pthread_create(&th[i], 0, thr, (void*)i); if (argc > 1 && rand()%2) usleep(rand()%1000); } usleep(20000); return 0; } Reported-by: Dmitry Vyukov Signed-off-by: Paolo Bonzini Signed-off-by: Radim Krčmář Signed-off-by: Zubin Mithra Signed-off-by: Greg Kroah-Hartman --- arch/x86/kvm/i8254.c | 5 +++-- arch/x86/kvm/x86.c | 4 ++-- 2 files changed, 5 insertions(+), 4 deletions(-) --- a/arch/x86/kvm/i8254.c +++ b/arch/x86/kvm/i8254.c @@ -678,7 +678,6 @@ static const struct kvm_io_device_ops sp .write = speaker_ioport_write, }; -/* Caller must hold slots_lock */ struct kvm_pit *kvm_create_pit(struct kvm *kvm, u32 flags) { struct kvm_pit *pit; @@ -733,6 +732,7 @@ struct kvm_pit *kvm_create_pit(struct kv pit->mask_notifier.func = pit_mask_notifer; kvm_register_irq_mask_notifier(kvm, 0, &pit->mask_notifier); + mutex_lock(&kvm->slots_lock); kvm_iodevice_init(&pit->dev, &pit_dev_ops); ret = kvm_io_bus_register_dev(kvm, KVM_PIO_BUS, KVM_PIT_BASE_ADDRESS, KVM_PIT_MEM_LENGTH, &pit->dev); @@ -747,13 +747,14 @@ struct kvm_pit *kvm_create_pit(struct kv if (ret < 0) goto fail_unregister; } + mutex_unlock(&kvm->slots_lock); return pit; fail_unregister: kvm_io_bus_unregister_dev(kvm, KVM_PIO_BUS, &pit->dev); - fail: + mutex_unlock(&kvm->slots_lock); kvm_unregister_irq_mask_notifier(kvm, 0, &pit->mask_notifier); kvm_unregister_irq_ack_notifier(kvm, &pit_state->irq_ack_notifier); kvm_free_irq_source_id(kvm, pit->irq_source_id); --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -3867,7 +3867,7 @@ long kvm_arch_vm_ioctl(struct file *filp sizeof(struct kvm_pit_config))) goto out; create_pit: - mutex_lock(&kvm->slots_lock); + mutex_lock(&kvm->lock); r = -EEXIST; if (kvm->arch.vpit) goto create_pit_unlock; @@ -3876,7 +3876,7 @@ long kvm_arch_vm_ioctl(struct file *filp if (kvm->arch.vpit) r = 0; create_pit_unlock: - mutex_unlock(&kvm->slots_lock); + mutex_unlock(&kvm->lock); break; case KVM_GET_IRQCHIP: { /* 0: PIC master, 1: PIC slave, 2: IOAPIC */