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=-9.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,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 C9EBCC432C0 for ; Wed, 27 Nov 2019 20:41:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 95FB421741 for ; Wed, 27 Nov 2019 20:41:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1574887268; bh=qpOfe/n+XafqdA3bd277vvX9ZgxGKO9nKXTsAQ4Xcxc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=jPky6gQ9dDvuWZF5Dr0T6bxcHgP20feefodw0c6kv0q4mRz9RwbtYRHb093BMmjxo F6LFhdKX7STe2dPF5cU1x4DGZiXlv8zmcSdhXJHmobxqVw+5HiZ79izb3H5NT+UUJT KFixwtM7BEb/JYlnSORuVd3ivO44d9FQdAqCE0vc= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729130AbfK0UlH (ORCPT ); Wed, 27 Nov 2019 15:41:07 -0500 Received: from mail.kernel.org ([198.145.29.99]:46004 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729123AbfK0UlE (ORCPT ); Wed, 27 Nov 2019 15:41:04 -0500 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 61D8621787; Wed, 27 Nov 2019 20:41:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1574887263; bh=qpOfe/n+XafqdA3bd277vvX9ZgxGKO9nKXTsAQ4Xcxc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=FIvQiTdiw0n+8J+79ByihWggdYBKtTRRaJdBqdBXXslMlSyRW+rNKc0cXjDkyID1x D7W5gXQnBap+8QZi0mhQ1K7lb6C3dl/aaCOQf5mc02XitCVqTb032Rw3p3fxKCwtE/ sUmv4Xj6y4riUmrD6sxjcKZ0CriJXh+froKNl3gQ= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Mattias Jacobsson <2pi@mok.nu>, Sasha Levin Subject: [PATCH 4.9 043/151] USB: misc: appledisplay: fix backlight update_status return code Date: Wed, 27 Nov 2019 21:30:26 +0100 Message-Id: <20191127203027.261800350@linuxfoundation.org> X-Mailer: git-send-email 2.24.0 In-Reply-To: <20191127203000.773542911@linuxfoundation.org> References: <20191127203000.773542911@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Mattias Jacobsson <2pi@mok.nu> [ Upstream commit 090158555ff8d194a98616034100b16697dd80d0 ] Upon success the update_status handler returns a positive number corresponding to the number of bytes transferred by usb_control_msg. However the return code of the update_status handler should indicate if an error occurred(negative) or how many bytes of the user's input to sysfs that was consumed. Return code zero indicates all bytes were consumed. The bug can for example result in the update_status handler being called twice, the second time with only the "unconsumed" part of the user's input to sysfs. Effectively setting an incorrect brightness. Change the update_status handler to return zero for all successful transactions and forward usb_control_msg's error code upon failure. Signed-off-by: Mattias Jacobsson <2pi@mok.nu> Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin --- drivers/usb/misc/appledisplay.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/drivers/usb/misc/appledisplay.c b/drivers/usb/misc/appledisplay.c index b8092bcf89a29..140af7754c1e6 100644 --- a/drivers/usb/misc/appledisplay.c +++ b/drivers/usb/misc/appledisplay.c @@ -160,8 +160,11 @@ static int appledisplay_bl_update_status(struct backlight_device *bd) pdata->msgdata, 2, ACD_USB_TIMEOUT); mutex_unlock(&pdata->sysfslock); - - return retval; + + if (retval < 0) + return retval; + else + return 0; } static int appledisplay_bl_get_brightness(struct backlight_device *bd) -- 2.20.1