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=-0.7 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS autolearn=unavailable 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 D0274C04A6B for ; Fri, 10 May 2019 03:31:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9F2612084A for ; Fri, 10 May 2019 03:31:21 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="key not found in DNS" (0-bit key) header.d=codeaurora.org header.i=@codeaurora.org header.b="eWgPmiy8"; dkim=fail reason="key not found in DNS" (0-bit key) header.d=codeaurora.org header.i=@codeaurora.org header.b="IwYvbwHy" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726907AbfEJDbV (ORCPT ); Thu, 9 May 2019 23:31:21 -0400 Received: from smtp.codeaurora.org ([198.145.29.96]:59128 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726882AbfEJDbU (ORCPT ); Thu, 9 May 2019 23:31:20 -0400 Received: by smtp.codeaurora.org (Postfix, from userid 1000) id F07C4607EB; Fri, 10 May 2019 03:31:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=codeaurora.org; s=default; t=1557459080; bh=ZdJ/UhXjQBUu2fWsqDO0l9IHAfnLU9pcY6tmqkKnt/I=; h=Subject:To:Cc:References:From:Date:In-Reply-To:From; b=eWgPmiy8q3KCGwv+cC+BJ7tbr7F/+kB1ksNKBz6GrsHwUjWYXd5wKBhOh2Sb7xdAn 9rjvXMrwFP+bmTzdMaObGYXHy1gONAKqfZZJlGe3JGN1Mwqm/fxaOME19CTHy6Sv29 TlpaS/Eoa/rRkGm/GXMywKmgCBnXRvSk1pkhcGVY= Received: from [10.204.78.109] (blr-c-bdr-fw-01_globalnat_allzones-outside.qualcomm.com [103.229.19.19]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) (Authenticated sender: gkohli@smtp.codeaurora.org) by smtp.codeaurora.org (Postfix) with ESMTPSA id 86DDC60592; Fri, 10 May 2019 03:31:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=codeaurora.org; s=default; t=1557459079; bh=ZdJ/UhXjQBUu2fWsqDO0l9IHAfnLU9pcY6tmqkKnt/I=; h=Subject:To:Cc:References:From:Date:In-Reply-To:From; b=IwYvbwHyjQBccR78yGpBpQQhaLwWMAnjUYY0tes3ePguKuTyPPWPHW6vzlJ7d83bU NTaVcZY5ldVw0WtlZK1QYHmZFcPUKeWf8CiqCGJbHYdCGIX5SscsO0jl/DsjGCQ7ng 8dQREHYyuK6fINknqSgt3oi3olZm5JrEyFriRmKY= DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org 86DDC60592 Authentication-Results: pdx-caf-mail.web.codeaurora.org; dmarc=none (p=none dis=none) header.from=codeaurora.org Authentication-Results: pdx-caf-mail.web.codeaurora.org; spf=none smtp.mailfrom=gkohli@codeaurora.org Subject: Re: [PATCH] driver core: Fix use-after-free and double free on glue directory To: Benjamin Herrenschmidt , Greg KH , Muchun Song Cc: rafael@kernel.org, linux-kernel , zhaowuyun@wingtech.com, linux-arm-msm@vger.kernel.org References: <20190423143258.96706-1-smuchun@gmail.com> <24b0fff3775147c04b006282727d94fea7f408b4.camel@kernel.crashing.org> <79fbc203bc9fa09d88ab2c4bff8635be4c293d49.camel@kernel.crashing.org> <20190504153440.GB19654@kroah.com> <73b783e634551420dfa249816514fb31ed3487b6.camel@kernel.crashing.org> From: Gaurav Kohli Message-ID: <6d755534-714b-5d04-3280-b27fd8a1df1b@codeaurora.org> Date: Fri, 10 May 2019 09:01:14 +0530 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.6.1 MIME-Version: 1.0 In-Reply-To: <73b783e634551420dfa249816514fb31ed3487b6.camel@kernel.crashing.org> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-arm-msm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-arm-msm@vger.kernel.org Thanks for the comment, will check the patch and update. Regards Gaurav On 5/10/2019 4:52 AM, Benjamin Herrenschmidt wrote: > On Thu, 2019-05-09 at 20:08 +0530, Gaurav Kohli wrote: >> Hi , >> >> Last patch will serialize the addition of child to parent directory, >> won't it affect performance. > > I doubt this is a significant issue, and there's already a global lock > taken once or twice in that path, the fix is purely to make sure that > the some locked section is used both for the lookup and the addition as > the bug comes from the window in between those two operations allowing > the object to be removed after it was "found". > > Cheers, > Ben. > >> >> Regards >> Gaurav >> >> On 5/4/2019 9:04 PM, Greg KH wrote: >>> On Sat, May 04, 2019 at 10:47:07PM +0800, Muchun Song wrote: >>>> Benjamin Herrenschmidt 于2019年5月2日周四 >>>> 下午2:25写道： >>>> >>>>>>> The basic idea yes, the whole bool *locked is horrid >>>>>>> though. >>>>>>> Wouldn't it >>>>>>> work to have a get_device_parent_locked that always returns >>>>>>> with >>>>>>> the mutex held, >>>>>>> or just move the mutex to the caller or something simpler >>>>>>> like this >>>>>>> ? >>>>>>> >>>>>> >>>>>> Greg and Rafael, do you have any suggestions for this? Or you >>>>>> also >>>>>> agree with Ben? >>>>> >>>>> Ping guys ? This is worth fixing... >>>> >>>> I also agree with you. But Greg and Rafael seem to be high >>>> latency right now. >>> >>> It's in my list of patches to get to, sorry, hopefully will dig out >>> of >>> that next week with the buffer that the merge window provides me. >>> >>> thanks, >>> >>> greg k-h >>> >> >> > -- Qualcomm India Private Limited, on behalf of Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project.