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=-3.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED 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 1B69AC7112A for ; Sun, 14 Oct 2018 15:38:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E344320876 for ; Sun, 14 Oct 2018 15:38:34 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E344320876 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 S1728972AbeJNXTy (ORCPT ); Sun, 14 Oct 2018 19:19:54 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:36798 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728015AbeJNXTy (ORCPT ); Sun, 14 Oct 2018 19:19:54 -0400 Received: from [2a02:8011:400e:2:cbab:f00:c93f:614] (helo=deadeye) by shadbolt.decadent.org.uk with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.84_2) (envelope-from ) id 1gBiMC-0004cY-0a; Sun, 14 Oct 2018 16:31:04 +0100 Received: from ben by deadeye with local (Exim 4.91) (envelope-from ) id 1gBiLP-0000Ee-Qq; Sun, 14 Oct 2018 16:30:15 +0100 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, "Jonathan Cameron" , "Martin Kelly" Date: Sun, 14 Oct 2018 16:25:41 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.16 075/366] iio:kfifo_buf: check for uint overflow In-Reply-To: X-SA-Exim-Connect-IP: 2a02:8011:400e:2:cbab:f00:c93f:614 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 3.16.60-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Martin Kelly commit 3d13de4b027d5f6276c0f9d3a264f518747d83f2 upstream. Currently, the following causes a kernel OOPS in memcpy: echo 1073741825 > buffer/length echo 1 > buffer/enable Note that using 1073741824 instead of 1073741825 causes "write error: Cannot allocate memory" but no OOPS. This is because 1073741824 == 2^30 and 1073741825 == 2^30+1. Since kfifo rounds up to the nearest power of 2, it will actually call kmalloc with roundup_pow_of_two(length) * bytes_per_datum. Using length == 1073741825 and bytes_per_datum == 2, we get: kmalloc(roundup_pow_of_two(1073741825) * 2 or kmalloc(2147483648 * 2) or kmalloc(4294967296) or kmalloc(UINT_MAX + 1) so this overflows to 0, causing kmalloc to return ZERO_SIZE_PTR and subsequent memcpy to fail once the device is enabled. Fix this by checking for overflow prior to allocating a kfifo. With this check added, the above code returns -EINVAL when enabling the buffer, rather than causing an OOPS. Signed-off-by: Martin Kelly Signed-off-by: Jonathan Cameron [bwh: Backported to 3.16: adjust filename] Signed-off-by: Ben Hutchings --- drivers/iio/kfifo_buf.c | 7 +++++++ 1 file changed, 7 insertions(+) --- a/drivers/iio/kfifo_buf.c +++ b/drivers/iio/kfifo_buf.c @@ -24,6 +24,13 @@ static inline int __iio_allocate_kfifo(s if ((length == 0) || (bytes_per_datum == 0)) return -EINVAL; + /* + * Make sure we don't overflow an unsigned int after kfifo rounds up to + * the next power of 2. + */ + if (roundup_pow_of_two(length) > UINT_MAX / bytes_per_datum) + return -EINVAL; + return __kfifo_alloc((struct __kfifo *)&buf->kf, length, bytes_per_datum, GFP_KERNEL); }