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=-2.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT 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 DC096C169C4 for ; Mon, 11 Feb 2019 08:29:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A6B6420863 for ; Mon, 11 Feb 2019 08:29:08 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="cYTjgZiJ" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727036AbfBKI3G (ORCPT ); Mon, 11 Feb 2019 03:29:06 -0500 Received: from mail-pg1-f196.google.com ([209.85.215.196]:39314 "EHLO mail-pg1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726015AbfBKI3G (ORCPT ); Mon, 11 Feb 2019 03:29:06 -0500 Received: by mail-pg1-f196.google.com with SMTP id r11so4642725pgp.6; Mon, 11 Feb 2019 00:29:05 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=yltjAFKS9GF5mtiDgNMgOQw/i68kr7Vg6EKoL/JMrV8=; b=cYTjgZiJW6rxt/mmCNFw9qybkYWOC8p53SjnIj+NGm8P7TMFKo8a3lyUruJqn46f3i Vqg2E0wPvrWVhQ4ZDa4Tzg42Bxqm3U+GQE51hKaQRgWp0coQbo8cHSK4CA0SZVBJoTqr Z43Mm9GQvsPMOQWLln/kQ4skXQjWaPuDZj0Mk5zJiKdDRBhhCrMaU2g083E2Bhn9knS5 Rx1yYeOwLhIqD0Ds/NnFKGaz4s2gsol5lh18FLlDPjLmSyMDsutFOjLCYM1PKWylEtFr tR98a09HGI97MstUJgISjs8FT/953K72JDLkK6EOemZPM6d8M9OvXZ2mGCxQt+r8b8d/ HZUw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=yltjAFKS9GF5mtiDgNMgOQw/i68kr7Vg6EKoL/JMrV8=; b=mZjh6V8MonCJ/koIJhdkpuf2nSZT/K49z1PhQOkc+5FfULLvyMvM/sIbqxdt+he5tS 2Wn0vTSqx8ztEQicFXrlVmYF+xxmguhbzUI0g4j5cdHArebhbhyu94t9Mo8UVelseEVg dWEFcrja24zS8WYCAdGIEuKm/nFWVJ/Z08BpC8BeLxehpDF5mtdgUnSbkzjQibAS0bYk Mvr0KZ0Q6VkqsiV5WtLFnt2B78Ug8bhiLWtV6AxO+wxpm3Auodv70raDVdVe6ELY0j3n mZvYTohnr7k2cIT8NURGPcsp+ODvh53wFwRiRKm5fd5Dx59fmtH+HbUXVcRt9fnmCLvG ASjA== X-Gm-Message-State: AHQUAuaWzavi3RciL8J6LdczsM8Y7hBBYgLIDfIjZ9+M/DyVqExQQv9V crMCCZwtMGmStXBjOr3byQE= X-Google-Smtp-Source: AHgI3IY98ex3WgD4epHUmKzrRyiDfHKbkiS699ZNBYNJkHr6gJyTcxcO++0hTrCjy+HXCC0dzzu2AQ== X-Received: by 2002:a63:e655:: with SMTP id p21mr17391343pgj.70.1549873745042; Mon, 11 Feb 2019 00:29:05 -0800 (PST) Received: from dtor-ws ([2620:15c:202:201:3adc:b08c:7acc:b325]) by smtp.gmail.com with ESMTPSA id f12sm11743822pgo.13.2019.02.11.00.29.04 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Mon, 11 Feb 2019 00:29:04 -0800 (PST) Date: Mon, 11 Feb 2019 00:29:02 -0800 From: Dmitry Torokhov To: Sven Van Asbroeck Cc: linux-input@vger.kernel.org, Tejun Heo , Linux Kernel Mailing List Subject: Re: [PATCH] Input: matrix_keypad - use flush_delayed_work() Message-ID: <20190211082902.GA95126@dtor-ws> References: <20190207224650.GA49861@dtor-ws> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Sven, On Sun, Feb 10, 2019 at 12:43:21PM -0500, Sven Van Asbroeck wrote: > Hi Dmitry, > > On Thu, Feb 7, 2019 at 5:46 PM Dmitry Torokhov > wrote: > > > > We should be using flush_delayed_work() instead of flush_work() in > > matrix_keypad_stop() to ensure that we are not missing work that is > > scheduled but not yet put in the workqueue (i.e. its delay timer has not > > expired yet). > > > > Could the following scenario cause a use-after-free? > (I am adding comments on lines starting with -->) > > a) user closes the device handle: > > static void matrix_keypad_stop(struct input_dev *dev) > { > struct matrix_keypad *keypad = input_get_drvdata(dev); > > spin_lock_irq(&keypad->lock); > keypad->stopped = true; > spin_unlock_irq(&keypad->lock); > > flush_work(&keypad->work.work); > --> > --> new interrupt comes in, and schedules new delayed keypad->work (1) It will not schedule new work because we check keypad->stopped flag in ISR. Thanks. -- Dmitry