From nobody Mon Apr 13 10:38:36 2026 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 1CA0AC433FE for ; Tue, 8 Nov 2022 03:34:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232773AbiKHDe1 (ORCPT ); Mon, 7 Nov 2022 22:34:27 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53032 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233376AbiKHDeI (ORCPT ); Mon, 7 Nov 2022 22:34:08 -0500 Received: from szxga02-in.huawei.com (szxga02-in.huawei.com [45.249.212.188]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 34E44B71; Mon, 7 Nov 2022 19:33:21 -0800 (PST) Received: from dggpemm500022.china.huawei.com (unknown [172.30.72.55]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4N5tw75355zHvn5; Tue, 8 Nov 2022 11:32:55 +0800 (CST) Received: from dggpemm500013.china.huawei.com (7.185.36.172) by dggpemm500022.china.huawei.com (7.185.36.162) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.31; Tue, 8 Nov 2022 11:33:19 +0800 Received: from ubuntu1804.huawei.com (10.67.175.36) by dggpemm500013.china.huawei.com (7.185.36.172) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.31; Tue, 8 Nov 2022 11:33:19 +0800 From: Chen Zhongjin To: , CC: , , Subject: [PATCH] media: dvb-core: Fix ignored return value in dvb_register_frontend() Date: Tue, 8 Nov 2022 11:30:05 +0800 Message-ID: <20221108033005.169095-1-chenzhongjin@huawei.com> X-Mailer: git-send-email 2.17.1 MIME-Version: 1.0 X-Originating-IP: [10.67.175.36] X-ClientProxiedBy: dggems703-chm.china.huawei.com (10.3.19.180) To dggpemm500013.china.huawei.com (7.185.36.172) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" In dvb_register_frontend(), dvb_register_device() is possible to fail but its return value is ignored. It will cause use-after-free when module is removed, because in dvb_unregister_frontend() it tries to unregister a not registered device. BUG: KASAN: use-after-free in dvb_remove_device+0x18b/0x1f0 [dvb_core] Read of size 4 at addr ffff88800dff4824 by task rmmod/428 CPU: 3 PID: 428 Comm: rmmod Call Trace: ... dvb_remove_device+0x18b/0x1f0 [dvb_core] dvb_unregister_frontend+0x7b/0x130 [dvb_core] vidtv_bridge_remove+0x6e/0x160 [dvb_vidtv_bridge] ... Fix this by catching return value of dvb_register_device(). However the fe->refcount can't be put to zero immediately, because there are still modules calling dvb_frontend_detach() when dvb_register_frontend() fails. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Chen Zhongjin --- drivers/media/dvb-core/dvb_frontend.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/drivers/media/dvb-core/dvb_frontend.c b/drivers/media/dvb-core= /dvb_frontend.c index 48e735cdbe6b..a7792ef4baf8 100644 --- a/drivers/media/dvb-core/dvb_frontend.c +++ b/drivers/media/dvb-core/dvb_frontend.c @@ -2986,6 +2986,7 @@ int dvb_register_frontend(struct dvb_adapter *dvb, .name =3D fe->ops.info.name, #endif }; + int ret; =20 dev_dbg(dvb->device, "%s:\n", __func__); =20 @@ -3019,8 +3020,13 @@ int dvb_register_frontend(struct dvb_adapter *dvb, "DVB: registering adapter %i frontend %i (%s)...\n", fe->dvb->num, fe->id, fe->ops.info.name); =20 - dvb_register_device(fe->dvb, &fepriv->dvbdev, &dvbdev_template, + ret =3D dvb_register_device(fe->dvb, &fepriv->dvbdev, &dvbdev_template, fe, DVB_DEVICE_FRONTEND, 0); + if (ret) { + dvb_frontend_put(fe); + mutex_unlock(&frontend_mutex); + return ret; + } =20 /* * Initialize the cache to the proper values according with the --=20 2.17.1