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 6CB29CCA481 for ; Fri, 3 Jun 2022 17:56:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231416AbiFCR4R (ORCPT ); Fri, 3 Jun 2022 13:56:17 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58124 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1345847AbiFCRzL (ORCPT ); Fri, 3 Jun 2022 13:55:11 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3A3CE44A11; Fri, 3 Jun 2022 10:53:00 -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 ams.source.kernel.org (Postfix) with ESMTPS id D787EB82189; Fri, 3 Jun 2022 17:52:58 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1E326C385A9; Fri, 3 Jun 2022 17:52:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1654278777; bh=wHaTodtD45mZ8oITybG8g60oCCAN8kY0JNM8000sTLE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=1aG9pRkjuAelzvipGcq8YUYZJd3Mca3rYgty1mMaKl8vwRIa1ZiXBlvuohEm+4Nm/ mWAFWYH426UJi7ls3JLUAMt+f5fFiyv3Xiim9qjb5Ehg40ej29KPHuVZ9RNMmPYA2h mgg4oGlqsa6pSw3kPpFZ3GyEz9WFAtr+b6dhRbbQ= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Lin Ma , "David S. Miller" , Sasha Levin Subject: [PATCH 5.17 08/75] nfc: pn533: Fix buggy cleanup order Date: Fri, 3 Jun 2022 19:42:52 +0200 Message-Id: <20220603173821.986074977@linuxfoundation.org> X-Mailer: git-send-email 2.36.1 In-Reply-To: <20220603173821.749019262@linuxfoundation.org> References: <20220603173821.749019262@linuxfoundation.org> User-Agent: quilt/0.66 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 b8cedb7093b2d1394cae9b86494cba4b62d3a30a ] When removing the pn533 device (i2c or USB), there is a logic error. The original code first cancels the worker (flush_delayed_work) and then destroys the workqueue (destroy_workqueue), leaving the timer the last one to be deleted (del_timer). This result in a possible race condition in a multi-core preempt-able kernel. That is, if the cleanup (pn53x_common_clean) is concurrently run with the timer handler (pn533_listen_mode_timer), the timer can queue the poll_work to the already destroyed workqueue, causing use-after-free. This patch reorder the cleanup: it uses the del_timer_sync to make sure the handler is finished before the routine will destroy the workqueue. Note that the timer cannot be activated by the worker again. static void pn533_wq_poll(struct work_struct *work) ... rc = pn533_send_poll_frame(dev); if (rc) return; if (cur_mod->len == 0 && dev->poll_mod_count > 1) mod_timer(&dev->listen_timer, ...); That is, the mod_timer can be called only when pn533_send_poll_frame() returns no error, which is impossible because the device is detaching and the lower driver should return ENODEV code. Signed-off-by: Lin Ma Signed-off-by: David S. Miller Signed-off-by: Sasha Levin --- drivers/nfc/pn533/pn533.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/drivers/nfc/pn533/pn533.c b/drivers/nfc/pn533/pn533.c index a491db46e3bd..d9f6367b9993 100644 --- a/drivers/nfc/pn533/pn533.c +++ b/drivers/nfc/pn533/pn533.c @@ -2787,13 +2787,14 @@ void pn53x_common_clean(struct pn533 *priv) { struct pn533_cmd *cmd, *n; + /* delete the timer before cleanup the worker */ + del_timer_sync(&priv->listen_timer); + flush_delayed_work(&priv->poll_work); destroy_workqueue(priv->wq); skb_queue_purge(&priv->resp_q); - del_timer(&priv->listen_timer); - list_for_each_entry_safe(cmd, n, &priv->cmd_queue, queue) { list_del(&cmd->queue); kfree(cmd); -- 2.35.1