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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 364C7C43334 for ; Wed, 15 Jun 2022 12:03:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240782AbiFOMDX convert rfc822-to-8bit (ORCPT ); Wed, 15 Jun 2022 08:03:23 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35798 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231396AbiFOMDV (ORCPT ); Wed, 15 Jun 2022 08:03:21 -0400 Received: from szxga01-in.huawei.com (szxga01-in.huawei.com [45.249.212.187]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 96985220DD for ; Wed, 15 Jun 2022 05:03:20 -0700 (PDT) Received: from kwepemi100012.china.huawei.com (unknown [172.30.72.56]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4LNP681LNDzgZMd; Wed, 15 Jun 2022 20:01:20 +0800 (CST) Received: from dggpemm500006.china.huawei.com (7.185.36.236) by kwepemi100012.china.huawei.com (7.221.188.202) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Wed, 15 Jun 2022 20:03:18 +0800 Received: from dggpemm500006.china.huawei.com ([7.185.36.236]) by dggpemm500006.china.huawei.com ([7.185.36.236]) with mapi id 15.01.2375.024; Wed, 15 Jun 2022 20:03:18 +0800 From: "chenjun (AM)" To: Will Deacon CC: "linux-kernel@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "catalin.marinas@arm.com" , "xuqiang (M)" Subject: Re: [PATCH] arm64/smp: check !ipi_desc[i] in arch_show_interrupts Thread-Topic: [PATCH] arm64/smp: check !ipi_desc[i] in arch_show_interrupts Thread-Index: AQHYcaRPXakPnzyBa0Cd74QU1zTpKQ== Date: Wed, 15 Jun 2022 12:03:17 +0000 Message-ID: <188b4432206b464d93776d80c23081bb@huawei.com> References: <20220527082236.78037-1-chenjun102@huawei.com> <20220609152003.GC3289@willie-the-truck> Accept-Language: zh-CN, en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [10.174.178.43] Content-Type: text/plain; charset="iso-2022-jp" Content-Transfer-Encoding: 8BIT MIME-Version: 1.0 X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 在 2022/6/9 23:20, Will Deacon 写道: > On Fri, May 27, 2022 at 08:22:36AM +0000, Chen Jun wrote: >> There is a potential dereferencing null pointer issue in >> arch_show_interrupts. >> >> Problem 1: >> int arch_show_interrupts(struct seq_file *p, int prec) >> for (i = 0; i < NR_IPI; i++) { >> seq_printf(p, "%10u ", irq_desc_kstat_cpu(ipi_desc[i], >> cpu)); >> >> Only ipi_desc[0..nr_ipi - 1] are initialized in set_smp_ipi_range. >> and ipi_desc[nr_ipi..NR_IPI] are NULL. >> irq_desc_kstat_cpu will dereference NULL pointer. >> For now, the problem can not be triggered, because NR_IPI is always >> equal to nr_ipi. >> >> Problem 2: >> If request_percpu_irq failed in set_smp_ipi_range, ipi_desc[i] >> would be NULL. >> irq_desc_kstat_cpu will dereference NULL pointer. >> >> check !ipi_desc[i] (as arm does) to avoid the problem. >> >> Signed-off-by: Chen Jun >> --- >> arch/arm64/kernel/smp.c | 3 +++ >> 1 file changed, 3 insertions(+) >> >> diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c >> index 62ed361a4376..3d54f464428b 100644 >> --- a/arch/arm64/kernel/smp.c >> +++ b/arch/arm64/kernel/smp.c >> @@ -781,6 +781,9 @@ int arch_show_interrupts(struct seq_file *p, int prec) >> unsigned int cpu, i; >> >> for (i = 0; i < NR_IPI; i++) { >> + if (!ipi_desc[i]) >> + continue; > > Why not just use nr_ipi instead of NR_IPI? Yee, that is what I do at first. But I noticed that: void __init set_smp_ipi_range(int ipi_base, int n) for (i = 0; i < nr_ipi; i++) { err = request_percpu_irq(ipi_base + i, ipi_handler, "IPI", &cpu_number); WARN_ON(err); ipi_desc[i] = irq_to_desc(ipi_base + i); If request_percpu_irq return a error, I not sure if ipi_desc[i] makes sense. > > Will > -- Regards Chen Jun