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 B1699C54EBD for ; Thu, 12 Jan 2023 14:36:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238739AbjALOgN (ORCPT ); Thu, 12 Jan 2023 09:36:13 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55486 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237897AbjALOfl (ORCPT ); Thu, 12 Jan 2023 09:35:41 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C76A26564 for ; Thu, 12 Jan 2023 06:26:28 -0800 (PST) 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 6CD5EB81E67 for ; Thu, 12 Jan 2023 14:26:27 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9C340C433D2; Thu, 12 Jan 2023 14:26:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1673533586; bh=CZfTW9O9xfl15/nV5+mNC2Vf4M0i0dGc0/QrgWqQteg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=PUYdRvIKYxgd/5/VRIOfUymzVXNPYe8DaOS+rvCB5MDEaLg/F3OF6BRPJo1v5P786 6BUo3cmgoSJva7dtpPP3Byb9BXseGdAqfE+zGH3vNZd0EL2Gj6uHaa1lu8bLrPiaA9 brUboz7niTBsQKWCpiBYXAlO1ORlypWF+eq0tWXg= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Lin Ma , kernel test robot , Mauro Carvalho Chehab , Sasha Levin Subject: [PATCH 5.10 526/783] media: dvbdev: adopts refcnt to avoid UAF Date: Thu, 12 Jan 2023 14:54:02 +0100 Message-Id: <20230112135548.601442764@linuxfoundation.org> X-Mailer: git-send-email 2.39.0 In-Reply-To: <20230112135524.143670746@linuxfoundation.org> References: <20230112135524.143670746@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: Lin Ma [ Upstream commit 0fc044b2b5e2d05a1fa1fb0d7f270367a7855d79 ] dvb_unregister_device() is known that prone to use-after-free. That is, the cleanup from dvb_unregister_device() releases the dvb_device even if there are pointers stored in file->private_data still refer to it. This patch adds a reference counter into struct dvb_device and delays its deallocation until no pointer refers to the object. Link: https://lore.kernel.org/linux-media/20220807145952.10368-1-linma@zju.edu.cn Signed-off-by: Lin Ma Reported-by: kernel test robot Signed-off-by: Mauro Carvalho Chehab Signed-off-by: Sasha Levin --- drivers/media/dvb-core/dvb_ca_en50221.c | 2 +- drivers/media/dvb-core/dvb_frontend.c | 2 +- drivers/media/dvb-core/dvbdev.c | 32 +++++++++++++++++++------ include/media/dvbdev.h | 31 +++++++++++++----------- 4 files changed, 44 insertions(+), 23 deletions(-) diff --git a/drivers/media/dvb-core/dvb_ca_en50221.c b/drivers/media/dvb-core/dvb_ca_en50221.c index cfc27629444f..fd476536d32e 100644 --- a/drivers/media/dvb-core/dvb_ca_en50221.c +++ b/drivers/media/dvb-core/dvb_ca_en50221.c @@ -157,7 +157,7 @@ static void dvb_ca_private_free(struct dvb_ca_private *ca) { unsigned int i; - dvb_free_device(ca->dvbdev); + dvb_device_put(ca->dvbdev); for (i = 0; i < ca->slot_count; i++) vfree(ca->slot_info[i].rx_buffer.data); diff --git a/drivers/media/dvb-core/dvb_frontend.c b/drivers/media/dvb-core/dvb_frontend.c index b28ea7204f23..b04638321b75 100644 --- a/drivers/media/dvb-core/dvb_frontend.c +++ b/drivers/media/dvb-core/dvb_frontend.c @@ -135,7 +135,7 @@ static void __dvb_frontend_free(struct dvb_frontend *fe) struct dvb_frontend_private *fepriv = fe->frontend_priv; if (fepriv) - dvb_free_device(fepriv->dvbdev); + dvb_device_put(fepriv->dvbdev); dvb_frontend_invoke_release(fe, fe->ops.release); diff --git a/drivers/media/dvb-core/dvbdev.c b/drivers/media/dvb-core/dvbdev.c index ec9ebff28552..7b28b483e4b2 100644 --- a/drivers/media/dvb-core/dvbdev.c +++ b/drivers/media/dvb-core/dvbdev.c @@ -107,7 +107,7 @@ static int dvb_device_open(struct inode *inode, struct file *file) new_fops = fops_get(dvbdev->fops); if (!new_fops) goto fail; - file->private_data = dvbdev; + file->private_data = dvb_device_get(dvbdev); replace_fops(file, new_fops); if (file->f_op->open) err = file->f_op->open(inode, file); @@ -171,6 +171,9 @@ int dvb_generic_release(struct inode *inode, struct file *file) } dvbdev->users++; + + dvb_device_put(dvbdev); + return 0; } EXPORT_SYMBOL(dvb_generic_release); @@ -487,6 +490,7 @@ int dvb_register_device(struct dvb_adapter *adap, struct dvb_device **pdvbdev, return -ENOMEM; } + kref_init(&dvbdev->ref); memcpy(dvbdev, template, sizeof(struct dvb_device)); dvbdev->type = type; dvbdev->id = id; @@ -517,7 +521,7 @@ int dvb_register_device(struct dvb_adapter *adap, struct dvb_device **pdvbdev, #endif dvbdev->minor = minor; - dvb_minors[minor] = dvbdev; + dvb_minors[minor] = dvb_device_get(dvbdev); up_write(&minor_rwsem); ret = dvb_register_media_device(dvbdev, type, minor, demux_sink_pads); @@ -557,6 +561,7 @@ void dvb_remove_device(struct dvb_device *dvbdev) down_write(&minor_rwsem); dvb_minors[dvbdev->minor] = NULL; + dvb_device_put(dvbdev); up_write(&minor_rwsem); dvb_media_device_free(dvbdev); @@ -568,21 +573,34 @@ void dvb_remove_device(struct dvb_device *dvbdev) EXPORT_SYMBOL(dvb_remove_device); -void dvb_free_device(struct dvb_device *dvbdev) +static void dvb_free_device(struct kref *ref) { - if (!dvbdev) - return; + struct dvb_device *dvbdev = container_of(ref, struct dvb_device, ref); kfree (dvbdev->fops); kfree (dvbdev); } -EXPORT_SYMBOL(dvb_free_device); + + +struct dvb_device *dvb_device_get(struct dvb_device *dvbdev) +{ + kref_get(&dvbdev->ref); + return dvbdev; +} +EXPORT_SYMBOL(dvb_device_get); + + +void dvb_device_put(struct dvb_device *dvbdev) +{ + if (dvbdev) + kref_put(&dvbdev->ref, dvb_free_device); +} void dvb_unregister_device(struct dvb_device *dvbdev) { dvb_remove_device(dvbdev); - dvb_free_device(dvbdev); + dvb_device_put(dvbdev); } EXPORT_SYMBOL(dvb_unregister_device); diff --git a/include/media/dvbdev.h b/include/media/dvbdev.h index e547cbeee431..6e736587aa1f 100644 --- a/include/media/dvbdev.h +++ b/include/media/dvbdev.h @@ -156,6 +156,7 @@ struct dvb_adapter { */ struct dvb_device { struct list_head list_head; + struct kref ref; const struct file_operations *fops; struct dvb_adapter *adapter; enum dvb_device_type type; @@ -187,6 +188,20 @@ struct dvb_device { void *priv; }; +/** + * dvb_device_get - Increase dvb_device reference + * + * @dvbdev: pointer to struct dvb_device + */ +struct dvb_device *dvb_device_get(struct dvb_device *dvbdev); + +/** + * dvb_device_get - Decrease dvb_device reference + * + * @dvbdev: pointer to struct dvb_device + */ +void dvb_device_put(struct dvb_device *dvbdev); + /** * dvb_register_adapter - Registers a new DVB adapter * @@ -231,29 +246,17 @@ int dvb_register_device(struct dvb_adapter *adap, /** * dvb_remove_device - Remove a registered DVB device * - * This does not free memory. To do that, call dvb_free_device(). + * This does not free memory. dvb_free_device() will do that when + * reference counter is empty * * @dvbdev: pointer to struct dvb_device */ void dvb_remove_device(struct dvb_device *dvbdev); -/** - * dvb_free_device - Free memory occupied by a DVB device. - * - * Call dvb_unregister_device() before calling this function. - * - * @dvbdev: pointer to struct dvb_device - */ -void dvb_free_device(struct dvb_device *dvbdev); /** * dvb_unregister_device - Unregisters a DVB device * - * This is a combination of dvb_remove_device() and dvb_free_device(). - * Using this function is usually a mistake, and is often an indicator - * for a use-after-free bug (when a userspace process keeps a file - * handle to a detached device). - * * @dvbdev: pointer to struct dvb_device */ void dvb_unregister_device(struct dvb_device *dvbdev); -- 2.35.1