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 EB5AEC7EE25 for ; Wed, 7 Jun 2023 20:35:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233942AbjFGUf3 (ORCPT ); Wed, 7 Jun 2023 16:35:29 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33758 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234085AbjFGUfW (ORCPT ); Wed, 7 Jun 2023 16:35:22 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0963026A3 for ; Wed, 7 Jun 2023 13:35:13 -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 dfw.source.kernel.org (Postfix) with ESMTPS id 9346F6455A for ; Wed, 7 Jun 2023 20:35:12 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id A780CC4339B; Wed, 7 Jun 2023 20:35:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1686170112; bh=Chv4QB+WTslAjhYhq1oMBJcqeXiztpGYI+GrTa/Tu1Y=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=e0iJdT0XDeM8iRkQ5OX7MRVA2XGn5cAsoUBuWRXdVzCBIXq7XpaFu1LySWsNpH+Eo 1ufkPwvVbBuSnQ6t+wkwtitZo8Qq+gMRtGIxE9y3jxlqqmWVaxTpCJtjltvx+ujbVC XPfu/CfBtMOycPSmaFsb48cAS8nYjMbEmaFApdeM= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Hyunwoo Kim , Mauro Carvalho Chehab , Sasha Levin Subject: [PATCH 4.19 49/88] media: dvb-core: Fix use-after-free due on race condition at dvb_net Date: Wed, 7 Jun 2023 22:16:06 +0200 Message-ID: <20230607200900.776324926@linuxfoundation.org> X-Mailer: git-send-email 2.41.0 In-Reply-To: <20230607200854.030202132@linuxfoundation.org> References: <20230607200854.030202132@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Hyunwoo Kim [ Upstream commit 4172385b0c9ac366dcab78eda48c26814b87ed1a ] A race condition may occur between the .disconnect function, which is called when the device is disconnected, and the dvb_device_open() function, which is called when the device node is open()ed. This results in several types of UAFs. The root cause of this is that you use the dvb_device_open() function, which does not implement a conditional statement that checks 'dvbnet->exit'. So, add 'remove_mutex` to protect 'dvbnet->exit' and use locked_dvb_net_open() function to check 'dvbnet->exit'. [mchehab: fix a checkpatch warning] Link: https://lore.kernel.org/linux-media/20221117045925.14297-3-imv4bel@gmail.com Signed-off-by: Hyunwoo Kim Signed-off-by: Mauro Carvalho Chehab Signed-off-by: Sasha Levin --- drivers/media/dvb-core/dvb_net.c | 38 +++++++++++++++++++++++++++++--- include/media/dvb_net.h | 4 ++++ 2 files changed, 39 insertions(+), 3 deletions(-) diff --git a/drivers/media/dvb-core/dvb_net.c b/drivers/media/dvb-core/dvb_net.c index 3f154755bbc63..6c44526bb7efa 100644 --- a/drivers/media/dvb-core/dvb_net.c +++ b/drivers/media/dvb-core/dvb_net.c @@ -1575,15 +1575,43 @@ static long dvb_net_ioctl(struct file *file, return dvb_usercopy(file, cmd, arg, dvb_net_do_ioctl); } +static int locked_dvb_net_open(struct inode *inode, struct file *file) +{ + struct dvb_device *dvbdev = file->private_data; + struct dvb_net *dvbnet = dvbdev->priv; + int ret; + + if (mutex_lock_interruptible(&dvbnet->remove_mutex)) + return -ERESTARTSYS; + + if (dvbnet->exit) { + mutex_unlock(&dvbnet->remove_mutex); + return -ENODEV; + } + + ret = dvb_generic_open(inode, file); + + mutex_unlock(&dvbnet->remove_mutex); + + return ret; +} + static int dvb_net_close(struct inode *inode, struct file *file) { struct dvb_device *dvbdev = file->private_data; struct dvb_net *dvbnet = dvbdev->priv; + mutex_lock(&dvbnet->remove_mutex); + dvb_generic_release(inode, file); - if(dvbdev->users == 1 && dvbnet->exit == 1) + if (dvbdev->users == 1 && dvbnet->exit == 1) { + mutex_unlock(&dvbnet->remove_mutex); wake_up(&dvbdev->wait_queue); + } else { + mutex_unlock(&dvbnet->remove_mutex); + } + return 0; } @@ -1591,7 +1619,7 @@ static int dvb_net_close(struct inode *inode, struct file *file) static const struct file_operations dvb_net_fops = { .owner = THIS_MODULE, .unlocked_ioctl = dvb_net_ioctl, - .open = dvb_generic_open, + .open = locked_dvb_net_open, .release = dvb_net_close, .llseek = noop_llseek, }; @@ -1610,10 +1638,13 @@ void dvb_net_release (struct dvb_net *dvbnet) { int i; + mutex_lock(&dvbnet->remove_mutex); dvbnet->exit = 1; + mutex_unlock(&dvbnet->remove_mutex); + if (dvbnet->dvbdev->users < 1) wait_event(dvbnet->dvbdev->wait_queue, - dvbnet->dvbdev->users==1); + dvbnet->dvbdev->users == 1); dvb_unregister_device(dvbnet->dvbdev); @@ -1632,6 +1663,7 @@ int dvb_net_init (struct dvb_adapter *adap, struct dvb_net *dvbnet, int i; mutex_init(&dvbnet->ioctl_mutex); + mutex_init(&dvbnet->remove_mutex); dvbnet->demux = dmx; for (i=0; i