Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752344AbdI0Kg0 (ORCPT ); Wed, 27 Sep 2017 06:36:26 -0400 Received: from mail-wm0-f65.google.com ([74.125.82.65]:38030 "EHLO mail-wm0-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751287AbdI0KgY (ORCPT ); Wed, 27 Sep 2017 06:36:24 -0400 X-Google-Smtp-Source: AOwi7QBbyW4Ak3xfhbF1OeEA0UihCgrMIBIfyWe9x7yfWJ9+W/2CwFrXBxpsrcjtKVpOFxYr8IT/RQ== Content-Type: text/plain; charset=us-ascii Mime-Version: 1.0 (Mac OS X Mail 10.3 \(3273\)) Subject: Re: [PATCH 4.4 03/26] lib/cmdline.c: fix get_options() overflow while parsing ranges From: Ilya Matveychikov In-Reply-To: <1498760667.1935.69.camel@codethink.co.uk> Date: Wed, 27 Sep 2017 11:36:21 +0100 Cc: linux-kernel@vger.kernel.org, stable@vger.kernel.org, Jonathan Corbet , Andrew Morton , Linus Torvalds , Greg Kroah-Hartman Message-Id: <22228CDC-6D1E-4339-BDE1-27A2FEA7094D@gmail.com> References: <20170627124528.581163327@linuxfoundation.org> <20170627124529.091915723@linuxfoundation.org> <1498760667.1935.69.camel@codethink.co.uk> To: Ben Hutchings X-Mailer: Apple Mail (2.3273) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from quoted-printable to 8bit by nfs id v8RAahwn007907 Content-Length: 1971 Lines: 67 > On Jun 29, 2017, at 7:24 PM, Ben Hutchings wrote: > > On Tue, 2017-06-27 at 14:49 +0200, Greg Kroah-Hartman wrote: >> 4.4-stable review patch. If anyone has any objections, please let me know. >> >> ------------------ >> >> From: Ilya Matveychikov >> >> commit a91e0f680bcd9e10c253ae8b62462a38bd48f09f upstream. >> >> When using get_options() it's possible to specify a range of numbers, >> like 1-100500. The problem is that it doesn't track array size while >> calling internally to get_range() which iterates over the range and >> fills the memory with numbers. > [...] >> --- a/lib/cmdline.c >> +++ b/lib/cmdline.c >> @@ -22,14 +22,14 @@ >> * the values[M, M+1, ..., N] into the ints array in get_options. >> */ >> >> -static int get_range(char **str, int *pint) >> +static int get_range(char **str, int *pint, int n) >> { >> int x, inc_counter, upper_range; >> >> (*str)++; >> upper_range = simple_strtol((*str), NULL, 0); >> inc_counter = upper_range - *pint; >> - for (x = *pint; x < upper_range; x++) >> + for (x = *pint; n && x < upper_range; x++, n--) >> *pint++ = x; >> return inc_counter; >> } > > But this still returns the number of integers in the range (minus 1)... > >> @@ -96,7 +96,7 @@ char *get_options(const char *str, int n >> break; >> if (res == 3) { >> int range_nums; >> - range_nums = get_range((char **)&str, ints + i); >> + range_nums = get_range((char **)&str, ints + i, nints - i); >> if (range_nums < 0) >> break; >> /* > > ...so that get_options() may set i > nints and ints[0] > nints - 1. > That will presumably result in out-of-bounds reads in callers. > > (This set of functions really deserves to be given a test suite and then > rewritten, because they are a *mess*.) > Please review the approach of fixing that: https://lkml.org/lkml/2017/9/19/105 > Ben. > > -- > Ben Hutchings > Software Developer, Codethink Ltd. > >