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=-4.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS 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 7E40AC43441 for ; Sun, 11 Nov 2018 20:35:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 10C8720818 for ; Sun, 11 Nov 2018 20:35:23 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 10C8720818 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=decadent.org.uk 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 S1731525AbeKLGYx (ORCPT ); Mon, 12 Nov 2018 01:24:53 -0500 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:49916 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730055AbeKLFsN (ORCPT ); Mon, 12 Nov 2018 00:48:13 -0500 Received: from [192.168.4.242] (helo=deadeye) by shadbolt.decadent.org.uk with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.89) (envelope-from ) id 1gLvsZ-0000oU-9K; Sun, 11 Nov 2018 19:58:43 +0000 Received: from ben by deadeye with local (Exim 4.91) (envelope-from ) id 1gLvsV-0001iA-Td; Sun, 11 Nov 2018 19:58:39 +0000 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Greg Kroah-Hartman" , "Jann Horn" Date: Sun, 11 Nov 2018 19:49:05 +0000 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.16 240/366] ibmasm: don't write out of bounds in read handler In-Reply-To: X-SA-Exim-Connect-IP: 192.168.4.242 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16.61-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Jann Horn commit a0341fc1981a950c1e902ab901e98f60e0e243f3 upstream. This read handler had a lot of custom logic and wrote outside the bounds of the provided buffer. This could lead to kernel and userspace memory corruption. Just use simple_read_from_buffer() with a stack buffer. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Jann Horn Signed-off-by: Greg Kroah-Hartman Signed-off-by: Ben Hutchings --- drivers/misc/ibmasm/ibmasmfs.c | 27 +++------------------------ 1 file changed, 3 insertions(+), 24 deletions(-) --- a/drivers/misc/ibmasm/ibmasmfs.c +++ b/drivers/misc/ibmasm/ibmasmfs.c @@ -507,35 +507,14 @@ static int remote_settings_file_close(st static ssize_t remote_settings_file_read(struct file *file, char __user *buf, size_t count, loff_t *offset) { void __iomem *address = (void __iomem *)file->private_data; - unsigned char *page; - int retval; int len = 0; unsigned int value; - - if (*offset < 0) - return -EINVAL; - if (count == 0 || count > 1024) - return 0; - if (*offset != 0) - return 0; - - page = (unsigned char *)__get_free_page(GFP_KERNEL); - if (!page) - return -ENOMEM; + char lbuf[20]; value = readl(address); - len = sprintf(page, "%d\n", value); - - if (copy_to_user(buf, page, len)) { - retval = -EFAULT; - goto exit; - } - *offset += len; - retval = len; + len = snprintf(lbuf, sizeof(lbuf), "%d\n", value); -exit: - free_page((unsigned long)page); - return retval; + return simple_read_from_buffer(buf, count, offset, lbuf, len); } static ssize_t remote_settings_file_write(struct file *file, const char __user *ubuff, size_t count, loff_t *offset)