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 0BBB2C6FD1F for ; Mon, 13 Mar 2023 15:10:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230204AbjCMPKP (ORCPT ); Mon, 13 Mar 2023 11:10:15 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36996 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231172AbjCMPJz (ORCPT ); Mon, 13 Mar 2023 11:09:55 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2A5C66C8BD; Mon, 13 Mar 2023 08:09:46 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id D98AAB81184; Mon, 13 Mar 2023 15:09:44 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id B5D55C433D2; Mon, 13 Mar 2023 15:09:41 +0000 (UTC) Message-ID: Date: Mon, 13 Mar 2023 16:09:40 +0100 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] media: hantro: fix use after free bug in hantro_remove due to race condition Content-Language: en-US From: Hans Verkuil To: Zheng Wang , ezequiel@vanguardiasur.com.ar Cc: p.zabel@pengutronix.de, mchehab@kernel.org, linux-media@vger.kernel.org, linux-rockchip@lists.infradead.org, linux-kernel@vger.kernel.org, hackerzheng666@gmail.com, 1395428693sheep@gmail.com, alex000young@gmail.com References: <20230307154157.1184826-1-zyytlz.wz@163.com> <43b48f87-2343-5855-e6c2-8f30319687c5@xs4all.nl> In-Reply-To: <43b48f87-2343-5855-e6c2-8f30319687c5@xs4all.nl> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 13/03/2023 16:08, Hans Verkuil wrote: > On 07/03/2023 16:41, Zheng Wang wrote: >> In hantro_probe, vpu->watchdog_work is bound with >> hantro_watchdog. Then hantro_end_prepare_run may >> be called to start the work. >> >> If we close the file or remove the module which will >> call hantro_release and hantro_remove to make cleanup, >> there may be a unfinished work. The possible sequence >> is as follows, which will cause a typical UAF bug. >> >> The same thing will happen in hantro_release, and use >> ctx after freeing it. >> >> Fix it by canceling the work before cleanup in hantro_release. >> >> CPU0 CPU1 >> >> |hantro_watchdog >> hantro_remove | >> v4l2_m2m_release | >> kfree(m2m_dev); | >> | >> | v4l2_m2m_get_curr_priv >> | m2m_dev->curr_ctx //use >> >> Signed-off-by: Zheng Wang >> --- >> drivers/media/platform/verisilicon/hantro_drv.c | 1 + >> 1 file changed, 1 insertion(+) >> >> diff --git a/drivers/media/platform/verisilicon/hantro_drv.c b/drivers/media/platform/verisilicon/hantro_drv.c >> index b0aeedae7b65..80bd856a4da9 100644 >> --- a/drivers/media/platform/verisilicon/hantro_drv.c >> +++ b/drivers/media/platform/verisilicon/hantro_drv.c >> @@ -1099,6 +1099,7 @@ static int hantro_remove(struct platform_device *pdev) >> >> v4l2_info(&vpu->v4l2_dev, "Removing %s\n", pdev->name); >> >> + cancel_delayed_work(&vpu->watchdog_work); > > Use cancel_delayed_work_sync(): that ensures the code waits for a running > watchdog function to finish. > > Ditto for the other patch. And also the cedrus and rkvdec patches. Regards, Hans > > Regards, > > Hans > >> media_device_unregister(&vpu->mdev); >> hantro_remove_dec_func(vpu); >> hantro_remove_enc_func(vpu); >