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 05BD3C43215 for ; Wed, 27 Nov 2019 21:25:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C709221556 for ; Wed, 27 Nov 2019 21:25:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1574889957; bh=FsvQRTDHzkmyfaLsTy8u40CfgdoIRfi8ccBGcX4mt+M=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=FgxvUo+BXAyvLSQ8CpOQVHMG5aXz7MxvTghpOHp4Q5IsQ3uIH8n4V1wm1T59sfXrC v6p6At2o4LYLfYJ9U/Q6vFt/vwFuy13AgM+y6Sf81jlbXTk3Na0zQjmtrS71lYZ3A7 Ic5Y7ir4Sg6iy8x1wZB1hKlV1+tu9fY31eKZxtAk= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731386AbfK0VBS (ORCPT ); Wed, 27 Nov 2019 16:01:18 -0500 Received: from mail.kernel.org ([198.145.29.99]:53382 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731688AbfK0VBQ (ORCPT ); Wed, 27 Nov 2019 16:01:16 -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 BB70F21555; Wed, 27 Nov 2019 21:01:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1574888476; bh=FsvQRTDHzkmyfaLsTy8u40CfgdoIRfi8ccBGcX4mt+M=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=KvxmAiJ0EXgQS8ci0x4zeJ0IS+CnfdQTyIO+ppEUnIvLeKcz0Lrh8GjiRVFlgR33k jqgud1wnimBwIzR4TWbwMzKwPZLctUbekoduqMllcYszaQeV1GP+DYz44y1SsEa1HV YYNonP5IoUAnJeAorGbAOR5SGnGEA/+YJ9g1bnJE= 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 4.19 096/306] USB: misc: appledisplay: fix backlight update_status return code Date: Wed, 27 Nov 2019 21:29:06 +0100 Message-Id: <20191127203121.908875694@linuxfoundation.org> X-Mailer: git-send-email 2.24.0 In-Reply-To: <20191127203114.766709977@linuxfoundation.org> References: <20191127203114.766709977@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@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 1c6da8d6cccf8..39ca31b4de466 100644 --- a/drivers/usb/misc/appledisplay.c +++ b/drivers/usb/misc/appledisplay.c @@ -148,8 +148,11 @@ 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