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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id BAD8BC61DA4 for ; Sat, 18 Mar 2023 17:36:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229746AbjCRRgP (ORCPT ); Sat, 18 Mar 2023 13:36:15 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39324 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229640AbjCRRgO (ORCPT ); Sat, 18 Mar 2023 13:36:14 -0400 Received: from www381.your-server.de (www381.your-server.de [78.46.137.84]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B1D9D31E3E; Sat, 18 Mar 2023 10:36:12 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=metafoo.de; s=default2002; h=Content-Transfer-Encoding:Content-Type:In-Reply-To:From: References:Cc:To:Subject:MIME-Version:Date:Message-ID:Sender:Reply-To: Content-ID:Content-Description:Resent-Date:Resent-From:Resent-Sender: Resent-To:Resent-Cc:Resent-Message-ID; bh=r7A7mdmBsBY9f3U2r41zJO5Uw7IfyxYxQsJX4tWnBic=; b=ANiUAJRwfDdBEzPXgKut6x0e7H JifM0Ql1RokHy27pqRMCgLTo+kgBNrfw+amBnQUeMac085ALnseR2o87hsa+0Fp3UVzZV97g3lVvg hSH8eLGSD5HFX40bVyxj2+O6vXgIhPSicCJYD2s+URiSoDrFhe5XvmH7YpkzEbRsqRrQzXLyFjRIJ 8LFGn83oHsgorJkYIGoAMTF/dpHl56qcJ+QwX62uVDH4j2Mo9yw2KcfOqqJ5iWKGTy/ZCOIr3Pwzi RNYC+QkK0AViteORpAy4p9ukYreIeJ8aVtieJBPn50InwMjrxZ6phI6WCDiKY7yVhn1XjKrLU3mnM k68LbttQ==; Received: from sslproxy01.your-server.de ([78.46.139.224]) by www381.your-server.de with esmtpsa (TLS1.3) tls TLS_AES_256_GCM_SHA384 (Exim 4.94.2) (envelope-from ) id 1pdaTP-0001Cp-Hi; Sat, 18 Mar 2023 18:36:07 +0100 Received: from [2604:5500:c0e5:eb00:da5e:d3ff:feff:933b] by sslproxy01.your-server.de with esmtpsa (TLSv1.3:TLS_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1pdaTP-000Nhv-3p; Sat, 18 Mar 2023 18:36:07 +0100 Message-ID: Date: Sat, 18 Mar 2023 10:36:04 -0700 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.8.0 Subject: Re: [PATCH] iio: at91-sama5d2_adc: Fix use after free bug in at91_adc_remove due to race condition Content-Language: en-US To: Jonathan Cameron , Zheng Wang Cc: eugen.hristev@collabora.com, nicolas.ferre@microchip.com, alexandre.belloni@bootlin.com, claudiu.beznea@microchip.com, linux-iio@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org References: <20230310091239.1440279-1-zyytlz.wz@163.com> <20230318173913.19e8a1b1@jic23-huawei> From: Lars-Peter Clausen In-Reply-To: <20230318173913.19e8a1b1@jic23-huawei> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Authenticated-Sender: lars@metafoo.de X-Virus-Scanned: Clear (ClamAV 0.103.8/26847/Sat Mar 18 08:21:32 2023) Precedence: bulk List-ID: X-Mailing-List: linux-iio@vger.kernel.org On 3/18/23 10:39, Jonathan Cameron wrote: > On Fri, 10 Mar 2023 17:12:39 +0800 > Zheng Wang wrote: > >> In at91_adc_probe, &st->touch_st.workq is bound with >> at91_adc_workq_handler. Then it will be started by irq >> handler at91_adc_touch_data_handler >> >> If we remove the driver which will call at91_adc_remove >> to make cleanup, there may be a unfinished work. >> >> The possible sequence is as follows: >> >> Fix it by finishing the work before cleanup in the at91_adc_remove >> >> CPU0 CPU1 >> >> |at91_adc_workq_handler >> at91_adc_remove | >> iio_device_unregister| >> iio_dev_release | >> kfree(iio_dev_opaque);| >> | >> |iio_push_to_buffers >> |&iio_dev_opaque->buffer_list >> |//use >> Fixes: 23ec2774f1cc ("iio: adc: at91-sama5d2_adc: add support for position and pressure channels") >> Signed-off-by: Zheng Wang >> --- >> drivers/iio/adc/at91-sama5d2_adc.c | 2 ++ >> 1 file changed, 2 insertions(+) >> >> diff --git a/drivers/iio/adc/at91-sama5d2_adc.c b/drivers/iio/adc/at91-sama5d2_adc.c >> index 50d02e5fc6fc..1b95d18d9e0b 100644 >> --- a/drivers/iio/adc/at91-sama5d2_adc.c >> +++ b/drivers/iio/adc/at91-sama5d2_adc.c >> @@ -2495,6 +2495,8 @@ static int at91_adc_remove(struct platform_device *pdev) >> struct iio_dev *indio_dev = platform_get_drvdata(pdev); >> struct at91_adc_state *st = iio_priv(indio_dev); >> >> + disable_irq_nosync(st->irq); >> + cancel_work_sync(&st->touch_st.workq); > I'd like some input form someone more familiar with this driver than I am. > > In particular, whilst it fixes the bug seen I'm not sure what the most > logical ordering for the disable is or the best way to do it. > > I'd prefer to see the irq cut off at source by disabling it at the device > feature that is generating the irq followed by cancelling or waiting for > completion of any in flight work. The usually way you'd do this by calling free_irq() before the cancel_work_sync().