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=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS 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 A01CDC432C3 for ; Wed, 20 Nov 2019 15:43:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7A5BE2071F for ; Wed, 20 Nov 2019 15:43:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732247AbfKTPnI (ORCPT ); Wed, 20 Nov 2019 10:43:08 -0500 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:52848 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730074AbfKTPkT (ORCPT ); Wed, 20 Nov 2019 10:40:19 -0500 Received: from [167.98.27.226] (helo=deadeye) by shadbolt.decadent.org.uk with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.89) (envelope-from ) id 1iXS5V-0004bQ-K9; Wed, 20 Nov 2019 15:40:13 +0000 Received: from ben by deadeye with local (Exim 4.93-RC1) (envelope-from ) id 1iXS5U-0004Lr-WF; Wed, 20 Nov 2019 15:40:13 +0000 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, Denis Kirjanov , "Zhiqiang Liu" , "Thomas Gleixner" , "Yunfeng Ye" Date: Wed, 20 Nov 2019 15:38:16 +0000 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) X-Patchwork-Hint: ignore Subject: [PATCH 3.16 66/83] genirq: Prevent NULL pointer dereference in resend_irqs() In-Reply-To: X-SA-Exim-Connect-IP: 167.98.27.226 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16.78-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Yunfeng Ye commit eddf3e9c7c7e4d0707c68d1bb22cc6ec8aef7d4a upstream. The following crash was observed: 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 The reason for this is that the interrupt resend mechanism happens in soft interrupt context, which is a asynchronous mechanism versus other operations on interrupts. free_irq() does not take resend handling into account. Thus, the irq descriptor might be already freed before the resend tasklet is executed. resend_irqs() does not check the return value of the interrupt descriptor lookup and derefences the return value unconditionally. 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 --> Ooops Fix this by adding a NULL pointer check in resend_irqs() before derefencing the irq descriptor. Fixes: a4633adcdbc1 ("[PATCH] genirq: add genirq sw IRQ-retrigger") Signed-off-by: Yunfeng Ye Signed-off-by: Thomas Gleixner Reviewed-by: Zhiqiang Liu Link: https://lkml.kernel.org/r/1630ae13-5c8e-901e-de09-e740b6a426a7@huawei.com Signed-off-by: Ben Hutchings --- kernel/irq/resend.c | 2 ++ 1 file changed, 2 insertions(+) --- a/kernel/irq/resend.c +++ b/kernel/irq/resend.c @@ -37,6 +37,8 @@ static void resend_irqs(unsigned long ar 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(irq, desc); local_irq_enable();