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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS 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 27D6CC6778C for ; Fri, 6 Jul 2018 18:23:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D0EAC216F9 for ; Fri, 6 Jul 2018 18:23:53 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D0EAC216F9 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934417AbeGFSXu (ORCPT ); Fri, 6 Jul 2018 14:23:50 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:51142 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S934440AbeGFSXq (ORCPT ); Fri, 6 Jul 2018 14:23:46 -0400 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.rdu2.redhat.com [10.11.54.5]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id DFA8C3468C; Fri, 6 Jul 2018 18:23:45 +0000 (UTC) Received: from [10.10.121.173] (ovpn-121-173.rdu2.redhat.com [10.10.121.173]) by smtp.corp.redhat.com (Postfix) with ESMTP id C91FF76CE; Fri, 6 Jul 2018 18:23:44 +0000 (UTC) Subject: Re: [PATCH v3 3/3] uio: fix crash after the device is unregistered To: xiubli@redhat.com, gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org References: <1530845836-49101-1-git-send-email-xiubli@redhat.com> <1530845836-49101-4-git-send-email-xiubli@redhat.com> Cc: hamish.martin@alliedtelesis.co.nz, jannh@google.com, pkalever@redhat.com, pkarampu@redhat.com, atumball@redhat.com, sabose@redhat.com From: Mike Christie Message-ID: <5B3FB3B0.7010105@redhat.com> Date: Fri, 6 Jul 2018 13:23:44 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.6.0 MIME-Version: 1.0 In-Reply-To: <1530845836-49101-4-git-send-email-xiubli@redhat.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.11.54.5 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.2]); Fri, 06 Jul 2018 18:23:45 +0000 (UTC) X-Greylist: inspected by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.2]); Fri, 06 Jul 2018 18:23:45 +0000 (UTC) for IP:'10.11.54.5' DOMAIN:'int-mx05.intmail.prod.int.rdu2.redhat.com' HELO:'smtp.corp.redhat.com' FROM:'mchristi@redhat.com' RCPT:'' Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 07/05/2018 09:57 PM, xiubli@redhat.com wrote: > static irqreturn_t uio_interrupt(int irq, void *dev_id) > { > struct uio_device *idev = (struct uio_device *)dev_id; > - irqreturn_t ret = idev->info->handler(irq, idev->info); > + irqreturn_t ret; > + > + mutex_lock(&idev->info_lock); > + if (!idev->info) { > + ret = IRQ_NONE; > + goto out; > + } > > + ret = idev->info->handler(irq, idev->info); > if (ret == IRQ_HANDLED) > uio_event_notify(idev->info); > > +out: > + mutex_unlock(&idev->info_lock); > return ret; > } Do you need the interrupt related changes in this patch and the first one? When we do uio_unregister_device -> free_irq does free_irq return when there are no longer running interrupt handlers that we requested? If that is not the case then I think we can hit a similar bug. We do: __uio_register_device -> device_register -> device's refcount goes to zero so we do -> uio_device_release -> kfree(idev) and if it is possible the interrupt handler could still run after free_irq then we would end up doing: uio_interrupt -> mutex_lock(&idev->info_lock) -> idev access freed memory.