From patchwork Mon Nov 21 06:33:08 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Hyunwoo Kim X-Patchwork-Id: 13050351 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 0A98DC4332F for ; Mon, 21 Nov 2022 06:33:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229705AbiKUGdU (ORCPT ); Mon, 21 Nov 2022 01:33:20 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56270 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229489AbiKUGdS (ORCPT ); Mon, 21 Nov 2022 01:33:18 -0500 Received: from mail-pj1-x102b.google.com (mail-pj1-x102b.google.com [IPv6:2607:f8b0:4864:20::102b]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C827930F73 for ; Sun, 20 Nov 2022 22:33:14 -0800 (PST) Received: by mail-pj1-x102b.google.com with SMTP id w4-20020a17090ac98400b002186f5d7a4cso9908716pjt.0 for ; Sun, 20 Nov 2022 22:33:14 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=theori.io; s=google; h=content-disposition:mime-version:message-id:subject:cc:to:from:date :from:to:cc:subject:date:message-id:reply-to; bh=rldQbVzv5ebudT94dGZh2jVY/qkQgmXwBXggpzupv6g=; b=FUXLpBXC985sjZvdr2/n7L886E22UrSSCgeTmKY/YRtMKh3+UNmA3BhhLhBQI+34Mn IJDgN5xFyBg/ALxwNwmIWJ4YZG6zrE/QOk1p2ERomztODtaBfJnQkpDTiDFj+3sdIhVc ZvHBg7n7Plw7Lml7AVVCzOAvHaeWN1hag9A2U= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-disposition:mime-version:message-id:subject:cc:to:from:date :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=rldQbVzv5ebudT94dGZh2jVY/qkQgmXwBXggpzupv6g=; b=TpqWlPdJagOPHPbvHgdC1MsliWDGaAM7AhB93/kSs/0WFXahI/8hBwfy7AhzPRlY3w Ojah4r/njA5OgYvrjhXzSdJgTdJi7yLj0yU8arMOAYuJs3habw2TWP8RBW1mpesmaTKo gA3Zwgt7HcoHXEgA72G+b+Q3TixGokTRMAMm4nPaUZwIwC3R8HAQmBiJe8s41gIpiC0o BBU+jDaY99VmXar3OR8uas4E+IyZuSob4gzajKhFIXPDeRibYMgty30shkoeU0awWhYO sN7j9+a5quqg7mj7W+mRuvKU8nNWBYOYdzX10paMwOey0CJbgioaxP9qNj/rRyKIEc7b OsJw== X-Gm-Message-State: ANoB5pnpXTzh0Gkq4v4ScC+w48ndAwEmGKveUrCTyiuBvlfeyo1ggW9X 6DxPHc72n4KsPqX0K6MB18FfBQ== X-Google-Smtp-Source: AA0mqf66VffZbM1/0KybknJnOwPt5S0b1hE4ZfrN6xpKk4e8OzGYFNFZuL8Zo7e57awlk6ixqCTZ2A== X-Received: by 2002:a17:90a:4886:b0:211:42a9:d132 with SMTP id b6-20020a17090a488600b0021142a9d132mr19262919pjh.8.1669012394383; Sun, 20 Nov 2022 22:33:14 -0800 (PST) Received: from ubuntu ([121.133.63.188]) by smtp.gmail.com with ESMTPSA id 143-20020a621495000000b00565b259a52asm7854502pfu.1.2022.11.20.22.33.11 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 20 Nov 2022 22:33:13 -0800 (PST) Date: Sun, 20 Nov 2022 22:33:08 -0800 From: Hyunwoo Kim To: mchehab@kernel.org Cc: linux-media@vger.kernel.org, linux-usb@vger.kernel.org, tiwai@suse.de, v4bel@theori.io Subject: [PATCH] media: dvb-core: Fix use-after-free due to race condition occurring in dvb_ca_en50221 Message-ID: <20221121063308.GA33821@ubuntu> MIME-Version: 1.0 Content-Disposition: inline Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org If the device node of dvb_ca_en50221 is open() and the device is disconnected, a UAF may occur when calling close() on the device node. The root cause is that wake_up() and wait_event() for dvbdev->wait_queue are not implemented. So implement wait_event() function in dvb_ca_en50221_release() and add 'remove_mutex' which prevents race condition for 'ca->exit'. Signed-off-by: Hyunwoo Kim --- drivers/media/dvb-core/dvb_ca_en50221.c | 36 ++++++++++++++++++++++++- 1 file changed, 35 insertions(+), 1 deletion(-) diff --git a/drivers/media/dvb-core/dvb_ca_en50221.c b/drivers/media/dvb-core/dvb_ca_en50221.c index 15a08d8c69ef..60133a315701 100644 --- a/drivers/media/dvb-core/dvb_ca_en50221.c +++ b/drivers/media/dvb-core/dvb_ca_en50221.c @@ -151,6 +151,12 @@ struct dvb_ca_private { /* mutex serializing ioctls */ struct mutex ioctl_mutex; + + /* A mutex used when a device is disconnected */ + struct mutex remove_mutex; + + /* Whether the device is disconnected */ + int exit; }; static void dvb_ca_private_free(struct dvb_ca_private *ca) @@ -1709,12 +1715,22 @@ static int dvb_ca_en50221_io_open(struct inode *inode, struct file *file) dprintk("%s\n", __func__); - if (!try_module_get(ca->pub->owner)) + mutex_lock(&ca->remove_mutex); + + if (ca->exit) { + mutex_unlock(&ca->remove_mutex); + return -ENODEV; + } + + if (!try_module_get(ca->pub->owner)) { + mutex_unlock(&ca->remove_mutex); return -EIO; + } err = dvb_generic_open(inode, file); if (err < 0) { module_put(ca->pub->owner); + mutex_unlock(&ca->remove_mutex); return err; } @@ -1739,6 +1755,7 @@ static int dvb_ca_en50221_io_open(struct inode *inode, struct file *file) dvb_ca_private_get(ca); + mutex_unlock(&ca->remove_mutex); return 0; } @@ -1758,6 +1775,8 @@ static int dvb_ca_en50221_io_release(struct inode *inode, struct file *file) dprintk("%s\n", __func__); + mutex_lock(&ca->remove_mutex); + /* mark the CA device as closed */ ca->open = 0; dvb_ca_en50221_thread_update_delay(ca); @@ -1768,6 +1787,12 @@ static int dvb_ca_en50221_io_release(struct inode *inode, struct file *file) dvb_ca_private_put(ca); + if (dvbdev->users == 1 && ca->exit == 1) { + mutex_unlock(&ca->remove_mutex); + wake_up(&dvbdev->wait_queue); + } else + mutex_unlock(&ca->remove_mutex); + return err; } @@ -1891,6 +1916,7 @@ int dvb_ca_en50221_init(struct dvb_adapter *dvb_adapter, } mutex_init(&ca->ioctl_mutex); + mutex_init(&ca->remove_mutex); if (signal_pending(current)) { ret = -EINTR; @@ -1933,6 +1959,14 @@ void dvb_ca_en50221_release(struct dvb_ca_en50221 *pubca) dprintk("%s\n", __func__); + mutex_lock(&ca->remove_mutex); + ca->exit = 1; + mutex_unlock(&ca->remove_mutex); + + if (ca->dvbdev->users < 1) + wait_event(ca->dvbdev->wait_queue, + ca->dvbdev->users == 1); + /* shutdown the thread if there was one */ kthread_stop(ca->thread);