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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,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 8E2A6C3A5A7 for ; Wed, 4 Sep 2019 12:46:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 625EA21883 for ; Wed, 4 Sep 2019 12:46:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730020AbfIDMqj (ORCPT ); Wed, 4 Sep 2019 08:46:39 -0400 Received: from szxga06-in.huawei.com ([45.249.212.32]:40848 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1729398AbfIDMqj (ORCPT ); Wed, 4 Sep 2019 08:46:39 -0400 Received: from DGGEMS406-HUB.china.huawei.com (unknown [172.30.72.60]) by Forcepoint Email with ESMTP id 53398A45EB0F9F9D40D8 for ; Wed, 4 Sep 2019 20:46:37 +0800 (CST) Received: from [127.0.0.1] (10.177.251.225) by DGGEMS406-HUB.china.huawei.com (10.3.19.206) with Microsoft SMTP Server id 14.3.439.0; Wed, 4 Sep 2019 20:46:31 +0800 To: From: Yunfeng Ye Subject: [PATCH] genirq: Fix NULL pointer dereference in resend_irqs() CC: Zhiqiang Liu , Message-ID: <1630ae13-5c8e-901e-de09-e740b6a426a7@huawei.com> Date: Wed, 4 Sep 2019 20:46:25 +0800 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.6.1 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.177.251.225] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Oops occur when running qemu on arm64: Unable to handle kernel NULL pointer dereference at 0000000000000158 Internal error: Oops: 96000004 [#1] SMP pc : resend_irqs+0x68/0xb0 lr : resend_irqs+0x64/0xb0 ... Call trace: resend_irqs+0x68/0xb0 tasklet_action_common.isra.6+0x84/0x138 tasklet_action+0x2c/0x38 __do_softirq+0x120/0x324 run_ksoftirqd+0x44/0x60 smpboot_thread_fn+0x1ac/0x1e8 kthread+0x134/0x138 ret_from_fork+0x10/0x18 As we know, softirq is a asynchronous mechanism. The process of free irqs does not take resend irq handling into account. Thus, the irq_desc may be already freed before softirq running, and resend_irqs() does not check the validation of irq_desc, finally, the Oops occur. Process is as follows: 1): __setup_irq irq_startup check_irq_resend // activate softirq to handle resend irq 2): irq_domain_free_irqs irq_free_descs free_desc call_rcu(&desc->rcu, delayed_free_desc) 3): __do_softirq tasklet_action resend_irqs desc = irq_to_desc(irq) desc->handle_irq(desc) // desc is NULL, Oops occur Fix this by checking for a NULL pointer when get @irq_desc in resend_irqs(). Signed-off-by: Yunfeng Ye Reviewed-by: Zhiqiang Liu --- kernel/irq/resend.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/kernel/irq/resend.c b/kernel/irq/resend.c index 95414ad..98c04ca5 100644 --- a/kernel/irq/resend.c +++ b/kernel/irq/resend.c @@ -36,6 +36,8 @@ static void resend_irqs(unsigned long arg) irq = find_first_bit(irqs_resend, nr_irqs); clear_bit(irq, irqs_resend); desc = irq_to_desc(irq); + if (!desc) + continue; local_irq_disable(); desc->handle_irq(desc); local_irq_enable(); -- 1.8.3.1