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=-13.6 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT 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 8E933C4363D for ; Thu, 1 Oct 2020 01:38:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4A6CD207F7 for ; Thu, 1 Oct 2020 01:38:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1601516307; bh=XZMO4TFRTZP9b5yzSScYL7RC7vJy1GH6mjdF75Dp63Q=; h=From:To:Cc:Subject:Date:List-ID:From; b=XTTJKb7pMshVBkWF9XYtZgclFNaJU2lE4TYyQ+Z869zPjsPLlou6IMfTd67R7Gy8m dEwvDR1dso/R+CSycs7T7hxHgHzTNRhswVmjGEXfRFk0cYw6t71r+SIFXcFYScb00u 8PLWksLE1GSTYGATj2yYgMLQJWkKnxsoLCF39NPw= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730238AbgJABiZ (ORCPT ); Wed, 30 Sep 2020 21:38:25 -0400 Received: from mail.kernel.org ([198.145.29.99]:40044 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725800AbgJABiY (ORCPT ); Wed, 30 Sep 2020 21:38:24 -0400 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 08041207C3; Thu, 1 Oct 2020 01:38:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1601516304; bh=XZMO4TFRTZP9b5yzSScYL7RC7vJy1GH6mjdF75Dp63Q=; h=From:To:Cc:Subject:Date:From; b=saNzvhOF8SyN9uvJGhdWR4czhwd9sXkILvfsW8J69kKHEh2cP2XEUw79BEKtszGoK cSqCCLrryfDk/Wy0V2UFLxhLn+XZr/zR1pMhuHd4Fd5nBvODfA0X8Td9cVwZeUPxJp YcilWetfHKSBiUzrn2g9GGq7+EkaxLkmWyrBUouk= From: Sasha Levin To: kys@microsoft.com, haiyangz@microsoft.com, sthemmin@microsoft.com, wei.liu@kernel.org Cc: tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, x86@kernel.org, hpa@zytor.com, vkuznets@redhat.com, mikelley@microsoft.com, linux-hyperv@vger.kernel.org, linux-kernel@vger.kernel.org, Sasha Levin , stable@kernel.org Subject: [PATCH] x86/hyper-v: guard against cpu mask changes in hyperv_flush_tlb_others() Date: Wed, 30 Sep 2020 21:38:14 -0400 Message-Id: <20201001013814.2435935-1-sashal@kernel.org> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org cpumask can change underneath us, which is generally safe except when we call into hv_cpu_number_to_vp_number(): if cpumask ends up empty we pass num_cpu_possible() into hv_cpu_number_to_vp_number(), causing it to read garbage. As reported by KASAN: [ 83.504763] BUG: KASAN: slab-out-of-bounds in hyperv_flush_tlb_others (include/asm-generic/mshyperv.h:128 arch/x86/hyperv/mmu.c:112) [ 83.908636] Read of size 4 at addr ffff888267c01370 by task kworker/u8:2/106 [ 84.196669] CPU: 0 PID: 106 Comm: kworker/u8:2 Tainted: G W 5.4.60 #1 [ 84.196669] Hardware name: Microsoft Corporation Virtual Machine/Virtual Machine, BIOS 090008 12/07/2018 [ 84.196669] Workqueue: writeback wb_workfn (flush-8:0) [ 84.196669] Call Trace: [ 84.196669] dump_stack (lib/dump_stack.c:120) [ 84.196669] print_address_description.constprop.0 (mm/kasan/report.c:375) [ 84.196669] __kasan_report.cold (mm/kasan/report.c:507) [ 84.196669] kasan_report (arch/x86/include/asm/smap.h:71 mm/kasan/common.c:635) [ 84.196669] hyperv_flush_tlb_others (include/asm-generic/mshyperv.h:128 arch/x86/hyperv/mmu.c:112) [ 84.196669] flush_tlb_mm_range (arch/x86/include/asm/paravirt.h:68 arch/x86/mm/tlb.c:798) [ 84.196669] ptep_clear_flush (arch/x86/include/asm/tlbflush.h:586 mm/pgtable-generic.c:88) Fixes: 0e4c88f37693 ("x86/hyper-v: Use cheaper HVCALL_FLUSH_VIRTUAL_ADDRESS_{LIST,SPACE} hypercalls when possible") Cc: Vitaly Kuznetsov Cc: stable@kernel.org Signed-off-by: Sasha Levin --- arch/x86/hyperv/mmu.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/arch/x86/hyperv/mmu.c b/arch/x86/hyperv/mmu.c index 5208ba49c89a9..b1d6afc5fc4a3 100644 --- a/arch/x86/hyperv/mmu.c +++ b/arch/x86/hyperv/mmu.c @@ -109,7 +109,9 @@ static void hyperv_flush_tlb_others(const struct cpumask *cpus, * must. We will also check all VP numbers when walking the * supplied CPU set to remain correct in all cases. */ - if (hv_cpu_number_to_vp_number(cpumask_last(cpus)) >= 64) + int last = cpumask_last(cpus); + + if (last < num_possible_cpus() && hv_cpu_number_to_vp_number(last) >= 64) goto do_ex_hypercall; for_each_cpu(cpu, cpus) { -- 2.25.1