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=-2.9 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_NEOMUTT 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 25AF9C282DA for ; Thu, 18 Apr 2019 01:44:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E7E9B217FA for ; Thu, 18 Apr 2019 01:44:48 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="MBO6Wp3o" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387630AbfDRBos (ORCPT ); Wed, 17 Apr 2019 21:44:48 -0400 Received: from mail-pg1-f195.google.com ([209.85.215.195]:38168 "EHLO mail-pg1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729331AbfDRBor (ORCPT ); Wed, 17 Apr 2019 21:44:47 -0400 Received: by mail-pg1-f195.google.com with SMTP id j26so393933pgl.5; Wed, 17 Apr 2019 18:44:47 -0700 (PDT) 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=MzjPpnoXEbsEM/B5pimFouu3ItZ7AAJKqejdoIFMMLI=; b=MBO6Wp3oDEm+26DyRLbcD2J5evIuTXBdagfYhT4dukyZj7LKgu6r0nD1mP499TdcWR so78mannP5E4Ou3H6TRvL8u9i8RLGq3X8snZxWeRjaHG/N5G83c2ozhPgLelP3qJaJSh 9A7OXUvQFtoVcVt1Hv54waydQobr9r9ZoYqKHk8UW+N1I18s6SzJJItYMN0N87a51u4g 02oUdR2O1OOcP/9CsHfDOHWduO26tjHePxUG4wCIOPtgrDTJlHDne3qEIguOdHaGEZKl TrjJomGOJX/TRfqESYU5jdfFzu8DkpMP/Cx/PyCh4AaxP0QzeoA+EJZN7vXdOP0d74dP rwfQ== 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=MzjPpnoXEbsEM/B5pimFouu3ItZ7AAJKqejdoIFMMLI=; b=k70KyYjVOTVwG749jgMm8uFcjhg2j3j7SSrCdQSak3Lke5Z2VuXDBwnQ2TFOiQouHf rV6cxIcHWrV/Rwjvbu+8JZXbIhyXTT6LDwFIwEZdIzRzh5wyJ00ageRilGRRrjwydLIy RZ9dAqSRj8c00lIiG8EuLZ/CAmBRuvZYjpjGWDK8obohwEo/nypz3B6m8ThsF2FLbGHT /ojOyV57UGK5XLqrxhf/NmyXIWU9T6UcEHRhDVt9Aunc9avz7BTBQlTxauulrh4R1P6C /CGy4c4ZMpNdkWX7NSGzAdOYFOO+L1giz9UhyRpWxpQEB1SeypjDRbsKVZB/GLek909q l/VA== X-Gm-Message-State: APjAAAU3bObZus9d2WVmG7ebafZdwEFO7FetOGer3kTlM5DlI3YE9UlR weNH68SnWtvh1yxPEc63SO4= X-Google-Smtp-Source: APXvYqzuR6DAmLJtQtZaQO6y5ps8jDVm4PFfroRe7sRLxh4TI/CKzz63RBg8By1louuFyqbKFbbdZg== X-Received: by 2002:a63:1043:: with SMTP id 3mr85617214pgq.283.1555551886015; Wed, 17 Apr 2019 18:44:46 -0700 (PDT) Received: from localhost ([210.162.55.198]) by smtp.gmail.com with ESMTPSA id r76sm613616pfa.39.2019.04.17.18.44.44 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Wed, 17 Apr 2019 18:44:44 -0700 (PDT) Date: Thu, 18 Apr 2019 01:43:21 +0000 From: "dmitry.torokhov@gmail.com" To: Mukesh Ojha Cc: linux-input@vger.kernel.org, linux-kernel@vger.kernel.org, Gaurav Kohli , Peter Hutterer , Martin Kepplinger , "Paul E. McKenney" Subject: Re: [PATCH v2] Input: uinput: Avoid Object-Already-Free with a global lock Message-ID: <20190418014321.dptin7tpxpldhsns@penguin> References: <1554883176-24318-1-git-send-email-mojha@codeaurora.org> <7299a6db-38b7-75c7-633a-00d2257eba45@codeaurora.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <7299a6db-38b7-75c7-633a-00d2257eba45@codeaurora.org> User-Agent: NeoMutt/20170113 (1.7.2) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Mukesh, On Mon, Apr 15, 2019 at 03:35:51PM +0530, Mukesh Ojha wrote: > > Hi Dmitry, > > Can you please have a look at this patch ? as this seems to reproducing > quite frequently > > Thanks, > Mukesh > > On 4/10/2019 1:29 PM, Mukesh Ojha wrote: > > uinput_destroy_device() gets called from two places. In one place, > > uinput_ioctl_handler() where it is protected under a lock > > udev->mutex but there is no protection on udev device from freeing > > inside uinput_release(). uinput_release() should be called when last file handle to the uinput instance is being dropped, so there should be no other users and thus we can't be racing with anyone. > > > > This can result in Object-Already-Free case where uinput parent > > device already got freed while a child being inserted inside it. > > That result in a double free case for parent while kernfs_put() > > being done for child in a failure path of adding a node. Can you please describe scenario in more detail? How do you free the parent device while child input device is being registered? Thanks. - Dmitry