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=-10.4 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS, T_DKIMWL_WL_MED,USER_AGENT_GIT,USER_IN_DEF_DKIM_WL 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 0659DC3279B for ; Fri, 6 Jul 2018 15:13:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B6AB222CB2 for ; Fri, 6 Jul 2018 15:13:17 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="FLPY33x1" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B6AB222CB2 Authentication-Results: mail.kernel.org; dmarc=fail (p=reject dis=none) header.from=google.com 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 S933219AbeGFPNP (ORCPT ); Fri, 6 Jul 2018 11:13:15 -0400 Received: from mail-ua0-f201.google.com ([209.85.217.201]:37417 "EHLO mail-ua0-f201.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932635AbeGFPNN (ORCPT ); Fri, 6 Jul 2018 11:13:13 -0400 Received: by mail-ua0-f201.google.com with SMTP id z33-v6so3529176uah.4 for ; Fri, 06 Jul 2018 08:13:12 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:date:message-id:subject:from:to:cc; bh=R1zve2zgmlb4kooJs7DKxUHxVCMuzZdZmn6sw6MVakw=; b=FLPY33x1Dr6j+4+2rCld0CVuTnbleh3jrGvFcAMi628PqViySrTHx4qRu86EkrwBcD Jnk98jZYKaOSCOZsf2vQE4RMFxwzqFliELNGNPZpoC0/pFpG1QMlNTTNjTk2Xcpgbce/ kHxFtWk2AFa4YjbiE7fYFDh4whjhwf/nnk7MbHUSpTOxKUXLKOgKtWY9stX1WiIMLSln NLl/OS3r0dx8/LnPFsqDofO22rFIZB0L8D97fiWZnsRyMQuqAAdjpayOqrrhAx2E/yj/ jEnol4ndflRnFb8qixhl1w3esAFoFSpLneE/XNETZqd1lq3BoKQa0lPsThuGe4xL5ElC PBYA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:date:message-id:subject:from:to:cc; bh=R1zve2zgmlb4kooJs7DKxUHxVCMuzZdZmn6sw6MVakw=; b=jm6VEvsB1e1EWb2V9LWQhIYe0xCYN1yRFdyiazCqiweoMZnJIBY/JaznA1Isn+q1rb mcjF9nN9u5KLsUu8FX1lnJRKcV4Zz+AVQnpIwLvquEC/EtKmsneAnQggTWNTwW/V3HxI JwTeZ8qYyaInADVh2+QnMeA+g6FvTnBJoTVyxyyY3z9EFoHDQ1ulEReJLLiBdjp0VDNO Ti+D8ufBULGQ4QcQMTi5UEydANZradnQkacVEQAdByS9HjIyxPAq5zEqbtj5HrUNbZpm C1bYHgsPptp/2o1kDUPbpT4U9bWhcPAtJHzxkiQ92yTJlkammZ/qzSzx4DKEGw50t3VK 2tRQ== X-Gm-Message-State: APt69E05/p3mk6ZytRWKvX3ae+VLJYqp/vjC+hJ34w0RTbXDdaQtBH/T YqquSVTtLiKaGW1zVN5FfLoRlnxiKQ== X-Google-Smtp-Source: AAOMgpeNy1oNY4n9jj5KyQJF6nX5Tn2t4DnoqWdblniqid3ZwFNXpPIfmz4R5opDMrxeUabLQeDuSUwUgw== MIME-Version: 1.0 X-Received: by 2002:a1f:36c3:: with SMTP id d186-v6mr4901010vka.69.1530889992182; Fri, 06 Jul 2018 08:13:12 -0700 (PDT) Date: Fri, 6 Jul 2018 17:12:56 +0200 Message-Id: <20180706151256.30359-1-jannh@google.com> X-Mailer: git-send-email 2.18.0.399.gad0ab374a1-goog Subject: [PATCH] USB: yurex: fix out-of-bounds uaccess in read handler From: Jann Horn To: Greg Kroah-Hartman , jannh@google.com Cc: Tomoki Sekiyama , linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org 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 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 --- drivers/usb/misc/yurex.c | 23 ++++++----------------- 1 file changed, 6 insertions(+), 17 deletions(-) diff --git a/drivers/usb/misc/yurex.c b/drivers/usb/misc/yurex.c index 8abb6cbbd98a..3be40eaa1ac9 100644 --- a/drivers/usb/misc/yurex.c +++ b/drivers/usb/misc/yurex.c @@ -396,8 +396,7 @@ static ssize_t yurex_read(struct file *file, char __user *buffer, size_t count, loff_t *ppos) { struct usb_yurex *dev; - int retval = 0; - int bytes_read = 0; + int len = 0; char in_buffer[20]; unsigned long flags; @@ -405,26 +404,16 @@ static ssize_t yurex_read(struct file *file, char __user *buffer, size_t count, 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, -- 2.18.0.399.gad0ab374a1-goog