From patchwork Tue Jan 24 07:55:33 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Duoming Zhou X-Patchwork-Id: 646365 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 258EBC25B4E for ; Tue, 24 Jan 2023 07:55:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232654AbjAXHzz (ORCPT ); Tue, 24 Jan 2023 02:55:55 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34856 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229627AbjAXHzy (ORCPT ); Tue, 24 Jan 2023 02:55:54 -0500 Received: from zg8tndyumtaxlji0oc4xnzya.icoremail.net (zg8tndyumtaxlji0oc4xnzya.icoremail.net [46.101.248.176]) by lindbergh.monkeyblade.net (Postfix) with SMTP id E5DEC44A9; Mon, 23 Jan 2023 23:55:49 -0800 (PST) Received: from ubuntu.localdomain (unknown [112.254.167.99]) by mail-app2 (Coremail) with SMTP id by_KCgAXHyP3js9j+tkkCg--.54572S2; Tue, 24 Jan 2023 15:55:45 +0800 (CST) From: Duoming Zhou To: sean@mess.org, linux-media@vger.kernel.org Cc: maximlevitsky@gmail.com, mchehab@kernel.org, linux-kernel@vger.kernel.org, Duoming Zhou Subject: [PATCH v3] media: rc: Fix use-after-free bugs caused by ene_tx_irqsim() Date: Tue, 24 Jan 2023 15:55:33 +0800 Message-Id: <20230124075533.30152-1-duoming@zju.edu.cn> X-Mailer: git-send-email 2.17.1 X-CM-TRANSID: by_KCgAXHyP3js9j+tkkCg--.54572S2 X-Coremail-Antispam: 1UD129KBjvJXoWxJFyxXrW3ZFW7AryUtF1rCrg_yoW5Wr45p3 95GFWfKryvqw429r17Xw48ZF15Wr4xJ34rZ34Sg34j9wn5CFyFqF9Yqa4j9a4rAFyrAFZF vr43Xw4fZFnxZFJanT9S1TB71UUUUUUqnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUkS14x267AKxVWUJVW8JwAFc2x0x2IEx4CE42xK8VAvwI8IcIk0 rVWrJVCq3wAFIxvE14AKwVWUJVWUGwA2ocxC64kIII0Yj41l84x0c7CEw4AK67xGY2AK02 1l84ACjcxK6xIIjxv20xvE14v26F1j6w1UM28EF7xvwVC0I7IYx2IY6xkF7I0E14v26F4j 6r4UJwA2z4x0Y4vEx4A2jsIE14v26rxl6s0DM28EF7xvwVC2z280aVCY1x0267AKxVW0oV Cq3wAS0I0E0xvYzxvE52x082IY62kv0487Mc02F40EFcxC0VAKzVAqx4xG6I80ewAv7VC0 I7IYx2IY67AKxVWUJVWUGwAv7VC2z280aVAFwI0_Jr0_Gr1lOx8S6xCaFVCjc4AY6r1j6r 4UM4x0Y48IcxkI7VAKI48JM4x0x7Aq67IIx4CEVc8vx2IErcIFxwCY02Avz4vE14v_GF4l 42xK82IYc2Ij64vIr41l4I8I3I0E4IkC6x0Yz7v_Jr0_Gr1lx2IqxVAqx4xG67AKxVWUJV WUGwC20s026x8GjcxK67AKxVWUGVWUWwC2zVAF1VAY17CE14v26r126r1DMIIYrxkI7VAK I48JMIIF0xvE2Ix0cI8IcVAFwI0_Jr0_JF4lIxAIcVC0I7IYx2IY6xkF7I0E14v26r1j6r 4UMIIF0xvE42xK8VAvwI8IcIk0rVWUJVWUCwCI42IY6I8E87Iv67AKxVWUJVW8JwCI42IY 6I8E87Iv6xkF7I0E14v26r4j6r4UJbIYCTnIWIevJa73UjIFyTuYvjfUekucDUUUU X-CM-SenderInfo: qssqjiasttq6lmxovvfxof0/1tbiAgIFAVZdtdVLGAASsu Precedence: bulk List-ID: X-Mailing-List: linux-media@vger.kernel.org When the ene device is detaching, function ene_remove() will be called. But there is no function to cancel tx_sim_timer in ene_remove(), the timer handler ene_tx_irqsim() could race with ene_remove(). As a result, the UAF bugs could happen, the process is shown below. (cleanup routine) | (timer routine) | mod_timer(&dev->tx_sim_timer, ..) ene_remove() | (wait a time) kfree(dev) //FREE | | ene_tx_irqsim() | dev->hw_lock //USE | ene_tx_sample(dev) //USE Fix by adding del_timer_sync(&dev->tx_sim_timer) in ene_remove(), The tx_sim_timer could stop before ene device is deallocated. What's more, The rc_unregister_device() and del_timer_sync() should be called first in ene_remove() and the deallocated functions such as free_irq(), release_region() and so on should be called behind them. Because the rc_unregister_device() is well synchronized. Otherwise, race conditions may happen. The situations that may lead to race conditions are shown below. Firstly, the rx receiver is disabled with ene_rx_disable() before rc_unregister_device() in ene_remove(), which means it can be enabled again if a process opens /dev/lirc0 between ene_rx_disable() and rc_unregister_device(). Secondly, the irqaction descriptor is freed by free_irq() before the rc device is unregistered, which means irqaction descriptor may be accessed again after it is deallocated. Thirdly, the timer can call ene_tx_sample() that can write to the io ports, which means the io ports could be accessed again after they are deallocated by release_region(). Therefore, the rc_unregister_device() and del_timer_sync() should be called first in ene_remove(). Suggested by: Sean Young Fixes: 9ea53b74df9c ("V4L/DVB: STAGING: remove lirc_ene0100 driver") Signed-off-by: Duoming Zhou --- Changes in v3: - Call rc_unregister_device() and del_timer_sync() first in ene_remove(). drivers/media/rc/ene_ir.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/media/rc/ene_ir.c b/drivers/media/rc/ene_ir.c index e09270916fb..11ee21a7db8 100644 --- a/drivers/media/rc/ene_ir.c +++ b/drivers/media/rc/ene_ir.c @@ -1106,6 +1106,8 @@ static void ene_remove(struct pnp_dev *pnp_dev) struct ene_device *dev = pnp_get_drvdata(pnp_dev); unsigned long flags; + rc_unregister_device(dev->rdev); + del_timer_sync(&dev->tx_sim_timer); spin_lock_irqsave(&dev->hw_lock, flags); ene_rx_disable(dev); ene_rx_restore_hw_buffer(dev); @@ -1113,7 +1115,6 @@ static void ene_remove(struct pnp_dev *pnp_dev) free_irq(dev->irq, dev); release_region(dev->hw_io, ENE_IO_SIZE); - rc_unregister_device(dev->rdev); kfree(dev); }