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=-2.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham 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 E98C0ECDFAA for ; Mon, 16 Jul 2018 07:44:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A124620837 for ; Mon, 16 Jul 2018 07:44:43 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A124620837 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linuxfoundation.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389418AbeGPIKo (ORCPT ); Mon, 16 Jul 2018 04:10:44 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:48238 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388522AbeGPIKo (ORCPT ); Mon, 16 Jul 2018 04:10:44 -0400 Received: from localhost (LFbn-1-12247-202.w90-92.abo.wanadoo.fr [90.92.61.202]) by mail.linuxfoundation.org (Postfix) with ESMTPSA id 72B56CA0; Mon, 16 Jul 2018 07:44:40 +0000 (UTC) From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Jann Horn Subject: [PATCH 4.4 08/43] USB: yurex: fix out-of-bounds uaccess in read handler Date: Mon, 16 Jul 2018 09:36:13 +0200 Message-Id: <20180716073512.701651346@linuxfoundation.org> X-Mailer: git-send-email 2.18.0 In-Reply-To: <20180716073511.796555857@linuxfoundation.org> References: <20180716073511.796555857@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Jann Horn commit f1e255d60ae66a9f672ff9a207ee6cd8e33d2679 upstream. In general, accessing userspace memory beyond the length of the supplied buffer in VFS read/write handlers can lead to both kernel memory corruption (via kernel_read()/kernel_write(), which can e.g. be triggered via sys_splice()) and privilege escalation inside userspace. Fix it by using simple_read_from_buffer() instead of custom logic. Fixes: 6bc235a2e24a ("USB: add driver for Meywa-Denki & Kayac YUREX") Signed-off-by: Jann Horn Cc: stable Signed-off-by: Greg Kroah-Hartman --- drivers/usb/misc/yurex.c | 23 ++++++----------------- 1 file changed, 6 insertions(+), 17 deletions(-) --- a/drivers/usb/misc/yurex.c +++ b/drivers/usb/misc/yurex.c @@ -414,8 +414,7 @@ static ssize_t yurex_read(struct file *f loff_t *ppos) { struct usb_yurex *dev; - int retval = 0; - int bytes_read = 0; + int len = 0; char in_buffer[20]; unsigned long flags; @@ -423,26 +422,16 @@ static ssize_t yurex_read(struct file *f mutex_lock(&dev->io_mutex); if (!dev->interface) { /* already disconnected */ - retval = -ENODEV; - goto exit; + mutex_unlock(&dev->io_mutex); + return -ENODEV; } spin_lock_irqsave(&dev->lock, flags); - bytes_read = snprintf(in_buffer, 20, "%lld\n", dev->bbu); + len = snprintf(in_buffer, 20, "%lld\n", dev->bbu); spin_unlock_irqrestore(&dev->lock, flags); - - if (*ppos < bytes_read) { - if (copy_to_user(buffer, in_buffer + *ppos, bytes_read - *ppos)) - retval = -EFAULT; - else { - retval = bytes_read - *ppos; - *ppos += bytes_read; - } - } - -exit: mutex_unlock(&dev->io_mutex); - return retval; + + return simple_read_from_buffer(buffer, count, ppos, in_buffer, len); } static ssize_t yurex_write(struct file *file, const char __user *user_buffer,