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=-3.8 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no 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 54045C54FCB for ; Thu, 23 Apr 2020 12:03:58 +0000 (UTC) Received: from mm01.cs.columbia.edu (mm01.cs.columbia.edu [128.59.11.253]) by mail.kernel.org (Postfix) with ESMTP id D5B9D2084D for ; Thu, 23 Apr 2020 12:03:57 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="o2GFQj9Q" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D5B9D2084D Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvmarm-bounces@lists.cs.columbia.edu Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 813C54B117; Thu, 23 Apr 2020 08:03:57 -0400 (EDT) X-Virus-Scanned: at lists.cs.columbia.edu Authentication-Results: mm01.cs.columbia.edu (amavisd-new); dkim=softfail (fail, message has been altered) header.i=@kernel.org Received: from mm01.cs.columbia.edu ([127.0.0.1]) by localhost (mm01.cs.columbia.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id zbNF+oRGWzcE; Thu, 23 Apr 2020 08:03:56 -0400 (EDT) Received: from mm01.cs.columbia.edu (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 187024B14A; Thu, 23 Apr 2020 08:03:56 -0400 (EDT) Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 1663B4B117 for ; Thu, 23 Apr 2020 08:03:55 -0400 (EDT) X-Virus-Scanned: at lists.cs.columbia.edu Received: from mm01.cs.columbia.edu ([127.0.0.1]) by localhost (mm01.cs.columbia.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id SSmqiPtyqG3B for ; Thu, 23 Apr 2020 08:03:53 -0400 (EDT) Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by mm01.cs.columbia.edu (Postfix) with ESMTPS id C543A4B0D8 for ; Thu, 23 Apr 2020 08:03:53 -0400 (EDT) Received: from disco-boy.misterjones.org (disco-boy.misterjones.org [51.254.78.96]) (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 AC4DD20781; Thu, 23 Apr 2020 12:03:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1587643432; bh=Yr+fkNmvLrz5b3ICOiyLazRf0Fuq3pgrt9QoX+DdBF8=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=o2GFQj9Q0+NAc5cK9SBz15ZI+lsTPKH5RaaTlo00DKMSU8Mf+4wnWhR2yi4iVPD/1 ZQS4NSzX6D2YB0ikmmy0a6UnvVy7sIQTefufvOBJoNam99BbXXOxlo/GzNLoUyFvq1 hNrb76I8BBsWHkZwlOSY9gnD9yIhbx5ngTuFyBhg= Received: from disco-boy.misterjones.org ([51.254.78.96] helo=www.loen.fr) by disco-boy.misterjones.org with esmtpsa (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.92) (envelope-from ) id 1jRaa6-005lQU-TF; Thu, 23 Apr 2020 13:03:51 +0100 MIME-Version: 1.0 Date: Thu, 23 Apr 2020 13:03:50 +0100 From: Marc Zyngier To: James Morse Subject: Re: [PATCH v3 5/6] KVM: arm64: vgic-v3: Retire all pending LPIs on vcpu destroy In-Reply-To: <2a0d1542-1964-c818-aae8-76f9227676b8@arm.com> References: <20200422161844.3848063-1-maz@kernel.org> <20200422161844.3848063-6-maz@kernel.org> <2a0d1542-1964-c818-aae8-76f9227676b8@arm.com> Message-ID: X-Sender: maz@kernel.org User-Agent: Roundcube Webmail/1.3.10 X-SA-Exim-Connect-IP: 51.254.78.96 X-SA-Exim-Rcpt-To: james.morse@arm.com, yuzenghui@huawei.com, linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org, eric.auger@redhat.com, Andre.Przywara@arm.com, julien@xen.org, julien.thierry.kdev@gmail.com, suzuki.poulose@arm.com X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false Cc: Julien Grall , kvm@vger.kernel.org, Andre Przywara , kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org X-BeenThere: kvmarm@lists.cs.columbia.edu X-Mailman-Version: 2.1.14 Precedence: list List-Id: Where KVM/ARM decisions are made List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Errors-To: kvmarm-bounces@lists.cs.columbia.edu Sender: kvmarm-bounces@lists.cs.columbia.edu Hi James, Thanks for the heads up. On 2020-04-23 12:35, James Morse wrote: > Hi Marc, Zenghui, > > On 22/04/2020 17:18, Marc Zyngier wrote: >> From: Zenghui Yu >> >> It's likely that the vcpu fails to handle all virtual interrupts if >> userspace decides to destroy it, leaving the pending ones stay in the >> ap_list. If the un-handled one is a LPI, its vgic_irq structure will >> be eventually leaked because of an extra refcount increment in >> vgic_queue_irq_unlock(). > >> diff --git a/virt/kvm/arm/vgic/vgic-init.c >> b/virt/kvm/arm/vgic/vgic-init.c >> index a963b9d766b73..53ec9b9d9bc43 100644 >> --- a/virt/kvm/arm/vgic/vgic-init.c >> +++ b/virt/kvm/arm/vgic/vgic-init.c >> @@ -348,6 +348,12 @@ void kvm_vgic_vcpu_destroy(struct kvm_vcpu *vcpu) >> { >> struct vgic_cpu *vgic_cpu = &vcpu->arch.vgic_cpu; >> >> + /* >> + * Retire all pending LPIs on this vcpu anyway as we're >> + * going to destroy it. >> + */ > > Looking at the other caller, do we need something like: > | if (vgic_cpu->lpis_enabled) > > ? Huh... On its own, this call is absolutely harmless even if you don't have LPIs. But see below. > >> + vgic_flush_pending_lpis(vcpu); >> + > > Otherwise, I get this on a gic-v2 machine!: > [ 1742.187139] BUG: KASAN: use-after-free in > vgic_flush_pending_lpis+0x250/0x2c0 > [ 1742.194302] Read of size 8 at addr ffff0008e1bf1f28 by task > qemu-system-aar/542 > [ 1742.203140] CPU: 2 PID: 542 Comm: qemu-system-aar Not tainted > 5.7.0-rc2-00006-g4fb0f7bb0e27 #2 > [ 1742.211780] Hardware name: ARM LTD ARM Juno Development > Platform/ARM Juno Development > Platform, BIOS EDK II Jul 30 2018 > [ 1742.222596] Call trace: > [ 1742.225059] dump_backtrace+0x0/0x328 > [ 1742.228738] show_stack+0x18/0x28 > [ 1742.232071] dump_stack+0x134/0x1b0 > [ 1742.235578] print_address_description.isra.0+0x6c/0x350 > [ 1742.240910] __kasan_report+0x10c/0x180 > [ 1742.244763] kasan_report+0x4c/0x68 > [ 1742.248268] __asan_report_load8_noabort+0x30/0x48 > [ 1742.253081] vgic_flush_pending_lpis+0x250/0x2c0 > [ 1742.257718] __kvm_vgic_destroy+0x1cc/0x478 > [ 1742.261919] kvm_vgic_destroy+0x30/0x48 > [ 1742.265773] kvm_arch_destroy_vm+0x20/0x128 > [ 1742.269976] kvm_put_kvm+0x3e0/0x8d0 > [ 1742.273567] kvm_vm_release+0x3c/0x60 > [ 1742.277248] __fput+0x218/0x630 > [ 1742.280406] ____fput+0x10/0x20 > [ 1742.283565] task_work_run+0xd8/0x1f0 > [ 1742.287245] do_exit+0x87c/0x2640 > [ 1742.290575] do_group_exit+0xd0/0x258 > [ 1742.294254] __arm64_sys_exit_group+0x3c/0x48 > [ 1742.298631] el0_svc_common.constprop.0+0x10c/0x348 > [ 1742.303529] do_el0_svc+0x48/0xd0 > [ 1742.306861] el0_sync_handler+0x11c/0x1b8 > [ 1742.310888] el0_sync+0x158/0x180 > [ 1742.315716] The buggy address belongs to the page: > [ 1742.320529] page:fffffe002366fc40 refcount:0 mapcount:0 > mapping:000000007e21d29f index:0x0 > [ 1742.328821] flags: 0x2ffff00000000000() > [ 1742.332678] raw: 2ffff00000000000 0000000000000000 ffffffff23660401 > 0000000000000000 > [ 1742.340449] raw: 0000000000000000 0000000000000000 00000000ffffffff > 0000000000000000 > [ 1742.348215] page dumped because: kasan: bad access detected > [ 1742.355304] Memory state around the buggy address: > [ 1742.360115] ffff0008e1bf1e00: ff ff ff ff ff ff ff ff ff ff ff ff > ff ff ff ff > [ 1742.367360] ffff0008e1bf1e80: ff ff ff ff ff ff ff ff ff ff ff ff > ff ff ff ff > [ 1742.374606] >ffff0008e1bf1f00: ff ff ff ff ff ff ff ff ff ff ff ff > ff ff ff ff > [ 1742.381851] ^ > [ 1742.386399] ffff0008e1bf1f80: ff ff ff ff ff ff ff ff ff ff ff ff > ff ff ff ff > [ 1742.393645] ffff0008e1bf2000: ff ff ff ff ff ff ff ff ff ff ff ff > ff ff ff ff > [ 1742.400889] > ================================================================== > [ 1742.408132] Disabling lock debugging due to kernel taint > > > With that: > Reviewed-by: James Morse I think this is slightly more concerning. The issue is that we have started freeing parts of the interrupt state already (we free the SPIs early in kvm_vgic_dist_destroy()). If a SPI was pending or active at this stage (i.e. present in the ap_list), we are going to iterate over memory that has been freed already. This is bad, and this can happen on GICv3 as well. I think this should solve it, but I need to test it on a GICv2 system: diff --git a/virt/kvm/arm/vgic/vgic-init.c b/virt/kvm/arm/vgic/vgic-init.c index 53ec9b9d9bc43..30dbec9fe0b4a 100644 --- a/virt/kvm/arm/vgic/vgic-init.c +++ b/virt/kvm/arm/vgic/vgic-init.c @@ -365,10 +365,10 @@ static void __kvm_vgic_destroy(struct kvm *kvm) vgic_debug_destroy(kvm); - kvm_vgic_dist_destroy(kvm); - kvm_for_each_vcpu(i, vcpu, kvm) kvm_vgic_vcpu_destroy(vcpu); + + kvm_vgic_dist_destroy(kvm); } void kvm_vgic_destroy(struct kvm *kvm) Thanks, M. -- Jazz is not dead. It just smells funny... _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm