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=-10.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 79B8EC432C3 for ; Sat, 16 Nov 2019 15:51:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 47F2F20B7C for ; Sat, 16 Nov 2019 15:51:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1573919514; bh=qpOfe/n+XafqdA3bd277vvX9ZgxGKO9nKXTsAQ4Xcxc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=aV6n/ylzd7XOZGslzme3AMSFZ/4qUvRtQDi22rpepFVQ14Ua1ZN31/a+ovGp4+ozD fFtiykI0ayRDc/oGwxZuEsUKYyCsT8LhJqRtTBTqckPIpy2aaCsEW+VeX9ICr89Eeo QX6RHQcT9mnt6rTYNCFJSugVWQCF6AWavaxbcIK4= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729924AbfKPPvx (ORCPT ); Sat, 16 Nov 2019 10:51:53 -0500 Received: from mail.kernel.org ([198.145.29.99]:60616 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730843AbfKPPvs (ORCPT ); Sat, 16 Nov 2019 10:51:48 -0500 Received: from sasha-vm.mshome.net (unknown [50.234.116.4]) (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 7C1002084B; Sat, 16 Nov 2019 15:51:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1573919507; bh=qpOfe/n+XafqdA3bd277vvX9ZgxGKO9nKXTsAQ4Xcxc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ONmA/lAxz8jkEnZ+iLubex0frOc7iY9P259auJUOQeQxJNaacTplkC1N016xqzlBh Z+e1S2R+BTX/M+dci62lE/2gvPoQJcdpBASZwqXKy7tLuSDLxgAYigL9kmDspq/KHQ gHh6uuPtI6xC+Cdc5tMZ0nQJVrhWu7yr3iuEK8xM= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Mattias Jacobsson <2pi@mok.nu>, Greg Kroah-Hartman , Sasha Levin , linux-usb@vger.kernel.org Subject: [PATCH AUTOSEL 4.9 31/99] USB: misc: appledisplay: fix backlight update_status return code Date: Sat, 16 Nov 2019 10:49:54 -0500 Message-Id: <20191116155103.10971-31-sashal@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20191116155103.10971-1-sashal@kernel.org> References: <20191116155103.10971-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review 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: 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