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 X-Spam-Level: X-Spam-Status: No, score=-9.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E32A2C43381 for ; Mon, 11 Mar 2019 20:09:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id AAFC02064A for ; Mon, 11 Mar 2019 20:09:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1552334946; bh=+u1e3/PVkxtbkOTEztkjRaMj7bgwpvCzON0ol0D8zI4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=zm8pG2+uv8inF6IVUM3bT18L9L7EbHzIE+zd01YyEaFgyCpig7aIPzqdfCuq65y7k nUu41e3O/ar/2rIv/CGx/6ZUgXkEOjZg050QltuL6anyCJqKKtKQkhb6xPddgaszbI Hr7pC8KU6qSTcNYY1LM/3yyfYsuty45rK3a8RkW4= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729060AbfCKUJF (ORCPT ); Mon, 11 Mar 2019 16:09:05 -0400 Received: from mail.kernel.org ([198.145.29.99]:34326 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728291AbfCKT44 (ORCPT ); Mon, 11 Mar 2019 15:56:56 -0400 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 15398214D8; Mon, 11 Mar 2019 19:56:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1552334215; bh=+u1e3/PVkxtbkOTEztkjRaMj7bgwpvCzON0ol0D8zI4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=z+F7u8dc2udef/pxmlxzmBysfWIfBCzEkKwF4W8RHmuT9ZrHQQXixUY2QtFZYaoLS UxMGywHmGqJ7y01BrB+nVDZJ6m82urFDMFcpiTmOq1H2vBPxQDzFfPg72MN2gRla71 Lqh1yJysMnlcdye9btLEx/rp5Kp+X9uhPJ89srXc= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Miguel Ojeda , Sasha Levin Subject: [PATCH AUTOSEL 4.20 50/52] auxdisplay: ht16k33: fix potential user-after-free on module unload Date: Mon, 11 Mar 2019 15:55:14 -0400 Message-Id: <20190311195516.137772-50-sashal@kernel.org> X-Mailer: git-send-email 2.19.1 In-Reply-To: <20190311195516.137772-1-sashal@kernel.org> References: <20190311195516.137772-1-sashal@kernel.org> MIME-Version: 1.0 X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Miguel Ojeda [ Upstream commit 69ef9bc54715fb1cb7786ada15774e469e822209 ] On module unload/remove, we need to ensure that work does not run after we have freed resources. Concretely, cancel_delayed_work() may return while the callback function is still running. >From kernel/workqueue.c: The work callback function may still be running on return, unless it returns true and the work doesn't re-arm itself. Explicitly flush or use cancel_delayed_work_sync() to wait on it. Link: https://lore.kernel.org/lkml/20190204220952.30761-1-TheSven73@googlemail.com/ Reported-by: Sven Van Asbroeck Reviewed-by: Dmitry Torokhov Reviewed-by: Sven Van Asbroeck Acked-by: Robin van der Gracht Signed-off-by: Miguel Ojeda Signed-off-by: Sasha Levin --- drivers/auxdisplay/ht16k33.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/auxdisplay/ht16k33.c b/drivers/auxdisplay/ht16k33.c index a43276c76fc6..21393ec3b9a4 100644 --- a/drivers/auxdisplay/ht16k33.c +++ b/drivers/auxdisplay/ht16k33.c @@ -509,7 +509,7 @@ static int ht16k33_remove(struct i2c_client *client) struct ht16k33_priv *priv = i2c_get_clientdata(client); struct ht16k33_fbdev *fbdev = &priv->fbdev; - cancel_delayed_work(&fbdev->work); + cancel_delayed_work_sync(&fbdev->work); unregister_framebuffer(fbdev->info); framebuffer_release(fbdev->info); free_page((unsigned long) fbdev->buffer); -- 2.19.1