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 B829BC6FD19 for ; Mon, 13 Mar 2023 13:47:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231179AbjCMNrh (ORCPT ); Mon, 13 Mar 2023 09:47:37 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48322 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231133AbjCMNrd (ORCPT ); Mon, 13 Mar 2023 09:47:33 -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 3EDC66F495; Mon, 13 Mar 2023 06:47:07 -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 E826DB810E8; Mon, 13 Mar 2023 13:47:05 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id DE390C433D2; Mon, 13 Mar 2023 13:47:02 +0000 (UTC) Message-ID: <1c1e4e60-3b90-f268-8012-3193e1de4769@xs4all.nl> Date: Mon, 13 Mar 2023 14:47:01 +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_release due to race condition Content-Language: en-US To: Zheng Hacker Cc: Zheng Wang , ezequiel@vanguardiasur.com.ar, p.zabel@pengutronix.de, mchehab@kernel.org, linux-media@vger.kernel.org, linux-rockchip@lists.infradead.org, linux-kernel@vger.kernel.org, 1395428693sheep@gmail.com, alex000young@gmail.com References: <20230307153542.1178065-1-zyytlz.wz@163.com> <7f9796d2-1885-a6f2-b9e3-d6ea58524033@xs4all.nl> From: Hans Verkuil In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 13/03/2023 14:45, Zheng Hacker wrote: > Hans Verkuil 于2023年3月13日周一 21:17写道: >> >> On 07/03/2023 16:35, 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..cf00ccaa7829 100644 >>> --- a/drivers/media/platform/verisilicon/hantro_drv.c >>> +++ b/drivers/media/platform/verisilicon/hantro_drv.c >>> @@ -601,6 +601,7 @@ static int hantro_release(struct file *filp) >>> * No need for extra locking because this was the last reference >>> * to this file. >>> */ >>> + cancel_delayed_work(&vpu->watchdog_work); >>> v4l2_m2m_ctx_release(ctx->fh.m2m_ctx); >>> v4l2_fh_del(&ctx->fh); >>> v4l2_fh_exit(&ctx->fh); >> >> drivers/media/platform/verisilicon/hantro_drv.c: In function ‘hantro_release’: >> drivers/media/platform/verisilicon/hantro_drv.c:604:30: error: ‘vpu’ undeclared (first use in this function); did you mean ‘fpu’? >> 604 | cancel_delayed_work(&vpu->watchdog_work); >> | ^~~ >> | fpu >> drivers/media/platform/verisilicon/hantro_drv.c:604:30: note: each undeclared identifier is reported only once for each function it appears in >> >> You clearly didn't compile this patch! >> > Sorry for my mistake. I was hurried to report the issue and discuss > with developer to confirm it . I'll complete it and test it locally. Was this UAF actually observed, or is it theoretical? Regards, Hans > > Best regards, > Zheng