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_HELO_NONE,SPF_PASS autolearn=no 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 DD096C432C0 for ; Wed, 20 Nov 2019 15:44:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id BD68220674 for ; Wed, 20 Nov 2019 15:44:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732346AbfKTPoQ (ORCPT ); Wed, 20 Nov 2019 10:44:16 -0500 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:52790 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730024AbfKTPkT (ORCPT ); Wed, 20 Nov 2019 10:40:19 -0500 Received: from [167.98.27.226] (helo=deadeye) by shadbolt.decadent.org.uk with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.89) (envelope-from ) id 1iXS5U-0004bK-Tp; Wed, 20 Nov 2019 15:40:13 +0000 Received: from ben by deadeye with local (Exim 4.93-RC1) (envelope-from ) id 1iXS5T-0004I5-PY; Wed, 20 Nov 2019 15:40:11 +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, Denis Kirjanov , "David Binderman" , "Ian Abbott" , "Greg Kroah-Hartman" Date: Wed, 20 Nov 2019 15:37:43 +0000 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) X-Patchwork-Hint: ignore Subject: [PATCH 3.16 33/83] staging: comedi: dt3000: Fix signed integer overflow 'divider * base' In-Reply-To: X-SA-Exim-Connect-IP: 167.98.27.226 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 3.16.78-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Ian Abbott commit b4d98bc3fc93ec3a58459948a2c0e0c9b501cd88 upstream. In `dt3k_ns_to_timer()` the following lines near the end of the function result in a signed integer overflow: prescale = 15; base = timer_base * (1 << prescale); divider = 65535; *nanosec = divider * base; (`divider`, `base` and `prescale` are type `int`, `timer_base` and `*nanosec` are type `unsigned int`. The value of `timer_base` will be either 50 or 100.) The main reason for the overflow is that the calculation for `base` is completely wrong. It should be: base = timer_base * (prescale + 1); which matches an earlier instance of this calculation in the same function. Reported-by: David Binderman Signed-off-by: Ian Abbott Link: https://lore.kernel.org/r/20190812111517.26803-1-abbotti@mev.co.uk Signed-off-by: Greg Kroah-Hartman Signed-off-by: Ben Hutchings --- drivers/staging/comedi/drivers/dt3000.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/drivers/staging/comedi/drivers/dt3000.c +++ b/drivers/staging/comedi/drivers/dt3000.c @@ -405,7 +405,7 @@ static int dt3k_ns_to_timer(unsigned int } prescale = 15; - base = timer_base * (1 << prescale); + base = timer_base * (prescale + 1); divider = 65535; *nanosec = divider * base; return (prescale << 16) | (divider);