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 2C60FC77B7A for ; Sat, 13 May 2023 17:58:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229482AbjEMR6Q (ORCPT ); Sat, 13 May 2023 13:58:16 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36110 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233590AbjEMR5v (ORCPT ); Sat, 13 May 2023 13:57:51 -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 A9D8C2D47; Sat, 13 May 2023 10:57:49 -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 6A19361C36; Sat, 13 May 2023 17:57:47 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4A94CC43442; Sat, 13 May 2023 17:57:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1684000666; bh=wQLhhjc/nu1gKQyvfutHSjiIwSyWN5kCMhdc5rNzry4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=CNaozJB/E/zHWbvpcNPvBHIW0aqcrTtLeI37AkOeiH/20A4MsmVtVRXp3WSsBwqn2 MIrNv2vrL469S3HtuMNcZ+bP3lZrdvVvQxHtQ/TAEVGuEPlRM601PnGW4eZQ87zFx5 O/ckYQuVjqodt/wo/yhI5we7z3xl78C40I//CM4A1I+pakpZHa6/9Sbn5Bn9PBzbib rs26QpXas9fV6/tTTufIMcrp4vZX6FUpV++yNVjeeHBTmPVEXTWxiTsOkbxdWJa0Lv cyecYxPd/PMLKpgkbqegbwfF3o8OYQuT8QBm4yGmpKNMTVVF/X6YxOY6W7aS24+7Cq A8DTz0ulGkI5w== Received: from mchehab by mail.kernel.org with local (Exim 4.96) (envelope-from ) id 1pxtV1-001ty5-1b; Sat, 13 May 2023 18:57:43 +0100 From: Mauro Carvalho Chehab Cc: Hyunwoo Kim , Mauro Carvalho Chehab , linux-kernel@vger.kernel.org, linux-media@vger.kernel.org Subject: [PATCH 14/24] media: dvb-core: Fix use-after-free due to race condition occurring in dvb_frontend Date: Sat, 13 May 2023 18:57:31 +0100 Message-Id: X-Mailer: git-send-email 2.40.1 In-Reply-To: <53558de2b5c4f4ee6bfcfbe34e27071c2d0073d5.1684000646.git.mchehab@kernel.org> References: <53558de2b5c4f4ee6bfcfbe34e27071c2d0073d5.1684000646.git.mchehab@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit To: unlisted-recipients:; (no To-header on input) Precedence: bulk List-ID: X-Mailing-List: linux-media@vger.kernel.org From: Hyunwoo Kim If the device node of dvb_frontend is open() and the device is disconnected, many kinds of UAFs may occur when calling close() on the device node. The root cause of this is that wake_up() for dvbdev->wait_queue is implemented in the dvb_frontend_release() function, but wait_event() is not implemented in the dvb_frontend_stop() function. So, implement wait_event() function in dvb_frontend_stop() and add 'remove_mutex' which prevents race condition for 'fe->exit'. [mchehab: fix a couple of checkpatch warnings] Link: https://lore.kernel.org/linux-media/20221117045925.14297-2-imv4bel@gmail.com Signed-off-by: Hyunwoo Kim Signed-off-by: Mauro Carvalho Chehab --- drivers/media/dvb-core/dvb_frontend.c | 39 ++++++++++++++++++++++++--- include/media/dvb_frontend.h | 6 ++++- 2 files changed, 40 insertions(+), 5 deletions(-) diff --git a/drivers/media/dvb-core/dvb_frontend.c b/drivers/media/dvb-core/dvb_frontend.c index cc0a789f09ae..375eb255df9e 100644 --- a/drivers/media/dvb-core/dvb_frontend.c +++ b/drivers/media/dvb-core/dvb_frontend.c @@ -809,6 +809,8 @@ static void dvb_frontend_stop(struct dvb_frontend *fe) dev_dbg(fe->dvb->device, "%s:\n", __func__); + mutex_lock(&fe->remove_mutex); + if (fe->exit != DVB_FE_DEVICE_REMOVED) fe->exit = DVB_FE_NORMAL_EXIT; mb(); @@ -818,6 +820,13 @@ static void dvb_frontend_stop(struct dvb_frontend *fe) kthread_stop(fepriv->thread); + mutex_unlock(&fe->remove_mutex); + + if (fepriv->dvbdev->users < -1) { + wait_event(fepriv->dvbdev->wait_queue, + fepriv->dvbdev->users == -1); + } + sema_init(&fepriv->sem, 1); fepriv->state = FESTATE_IDLE; @@ -2761,9 +2770,13 @@ static int dvb_frontend_open(struct inode *inode, struct file *file) struct dvb_adapter *adapter = fe->dvb; int ret; + mutex_lock(&fe->remove_mutex); + dev_dbg(fe->dvb->device, "%s:\n", __func__); - if (fe->exit == DVB_FE_DEVICE_REMOVED) + if (fe->exit == DVB_FE_DEVICE_REMOVED) { + mutex_unlock(&fe->remove_mutex); return -ENODEV; + } if (adapter->mfe_shared == 2) { mutex_lock(&adapter->mfe_lock); @@ -2794,8 +2807,10 @@ static int dvb_frontend_open(struct inode *inode, struct file *file) while (mferetry-- && (mfedev->users != -1 || mfepriv->thread)) { if (msleep_interruptible(500)) { - if (signal_pending(current)) + if (signal_pending(current)) { + mutex_unlock(&fe->remove_mutex); return -EINTR; + } } } @@ -2807,6 +2822,7 @@ static int dvb_frontend_open(struct inode *inode, struct file *file) if (mfedev->users != -1 || mfepriv->thread) { mutex_unlock(&adapter->mfe_lock); + mutex_unlock(&fe->remove_mutex); return -EBUSY; } adapter->mfe_dvbdev = dvbdev; @@ -2866,6 +2882,8 @@ static int dvb_frontend_open(struct inode *inode, struct file *file) if (adapter->mfe_shared) mutex_unlock(&adapter->mfe_lock); + + mutex_unlock(&fe->remove_mutex); return ret; err3: @@ -2887,6 +2905,8 @@ static int dvb_frontend_open(struct inode *inode, struct file *file) err0: if (adapter->mfe_shared) mutex_unlock(&adapter->mfe_lock); + + mutex_unlock(&fe->remove_mutex); return ret; } @@ -2897,6 +2917,8 @@ static int dvb_frontend_release(struct inode *inode, struct file *file) struct dvb_frontend_private *fepriv = fe->frontend_priv; int ret; + mutex_lock(&fe->remove_mutex); + dev_dbg(fe->dvb->device, "%s:\n", __func__); if ((file->f_flags & O_ACCMODE) != O_RDONLY) { @@ -2918,10 +2940,18 @@ static int dvb_frontend_release(struct inode *inode, struct file *file) } mutex_unlock(&fe->dvb->mdev_lock); #endif - if (fe->exit != DVB_FE_NO_EXIT) - wake_up(&dvbdev->wait_queue); if (fe->ops.ts_bus_ctrl) fe->ops.ts_bus_ctrl(fe, 0); + + if (fe->exit != DVB_FE_NO_EXIT) { + mutex_unlock(&fe->remove_mutex); + wake_up(&dvbdev->wait_queue); + } else { + mutex_unlock(&fe->remove_mutex); + } + + } else { + mutex_unlock(&fe->remove_mutex); } dvb_frontend_put(fe); @@ -3022,6 +3052,7 @@ int dvb_register_frontend(struct dvb_adapter *dvb, fepriv = fe->frontend_priv; kref_init(&fe->refcount); + mutex_init(&fe->remove_mutex); /* * After initialization, there need to be two references: one diff --git a/include/media/dvb_frontend.h b/include/media/dvb_frontend.h index e7c44870f20d..367d5381217b 100644 --- a/include/media/dvb_frontend.h +++ b/include/media/dvb_frontend.h @@ -686,7 +686,10 @@ struct dtv_frontend_properties { * @id: Frontend ID * @exit: Used to inform the DVB core that the frontend * thread should exit (usually, means that the hardware - * got disconnected. + * got disconnected). + * @remove_mutex: mutex that avoids a race condition between a callback + * called when the hardware is disconnected and the + * file_operations of dvb_frontend. */ struct dvb_frontend { @@ -704,6 +707,7 @@ struct dvb_frontend { int (*callback)(void *adapter_priv, int component, int cmd, int arg); int id; unsigned int exit; + struct mutex remove_mutex; }; /** -- 2.40.1