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=-8.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_2 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 53F7EC10DCE for ; Sun, 15 Mar 2020 13:10:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 25F13205C9 for ; Sun, 15 Mar 2020 13:10:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1584277813; bh=BclL4q3BTBO/kD7NJIxPs6flg8hZRErwfbM6JXTl1tg=; h=Date:From:To:Cc:Subject:In-Reply-To:References:List-ID:From; b=LBrpdySNcoehRh/30va5vSDcCFSouaKUB0eDj/24QbmAUbwbUlYDxYv6kwsSGY3CL nq3LgpupTaOHib8XTRbRry8BuQWN2f9ennCSdrXjYWXCODV+0RfVnDOysLh9BcNzPA A0ohmm3n50lH3K0NjOLWVXAG1zNh3elgzKXFza1I= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728574AbgCONKM (ORCPT ); Sun, 15 Mar 2020 09:10:12 -0400 Received: from mail.kernel.org ([198.145.29.99]:47952 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728541AbgCONKM (ORCPT ); Sun, 15 Mar 2020 09:10:12 -0400 Received: from archlinux (cpc149474-cmbg20-2-0-cust94.5-4.cable.virginm.net [82.4.196.95]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id AC24920575; Sun, 15 Mar 2020 13:10:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1584277812; bh=BclL4q3BTBO/kD7NJIxPs6flg8hZRErwfbM6JXTl1tg=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=2DjiD9Q+cU1FfVYaUqZY/fCaI0uuIPqBxb1neauhxLcSqJCaBZNe5N1N+WbfNi8/p gK+1oPmPzfJRlt3HfnoEcp74+f30wcDkYccFWIfSgxl0zpfOa9eR8xX1OvXu/nH8IQ qU5yHSIErZ9TvqvSv8TQfOrdJwyrjceWBnhhxBUY= Date: Sun, 15 Mar 2020 13:10:08 +0000 From: Jonathan Cameron To: Brian Masney Cc: Takashi Iwai , linux-iio@vger.kernel.org Subject: Re: [PATCH 2/2] iio: tsl2772: Use scnprintf() for avoiding potential buffer overflow Message-ID: <20200315131008.587ba23a@archlinux> In-Reply-To: <20200315103358.GA4674@onstation.org> References: <20200311074325.7922-1-tiwai@suse.de> <20200311074325.7922-3-tiwai@suse.de> <20200315095834.76f50454@archlinux> <20200315103358.GA4674@onstation.org> X-Mailer: Claws Mail 3.17.4 (GTK+ 2.24.32; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-iio-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-iio@vger.kernel.org On Sun, 15 Mar 2020 06:33:58 -0400 Brian Masney wrote: > On Sun, Mar 15, 2020 at 09:58:34AM +0000, Jonathan Cameron wrote: > > On Wed, 11 Mar 2020 08:43:25 +0100 > > Takashi Iwai wrote: > > > > > Since snprintf() returns the would-be-output size instead of the > > > actual output size, the succeeding calls may go beyond the given > > > buffer limit. Fix it by replacing with scnprintf(). > > > > > > Signed-off-by: Takashi Iwai > > > > This one is printing a short well defined list of values. No way they go > > anywhere near the smallest possible PAGE_SIZE buffer that it's printing > > into. > > > > Which is handy given the remaining space isn't adjusted as we add items > > to the string. Hence even with scnprintf it would overflow. > > > > Brian, can you take a look at this when you get a moment? > > I also agree that this won't overflow in practice, however we should fix > this up. Maybe the scnprintf() calls should be this: > > offset += scnprintf(buf + offset, PAGE_SIZE - offset, ...); Agreed. Jonathan > > Brian > > > > > > Thanks, > > > > Jonathan > > > > > --- > > > drivers/iio/light/tsl2772.c | 4 ++-- > > > 1 file changed, 2 insertions(+), 2 deletions(-) > > > > > > diff --git a/drivers/iio/light/tsl2772.c b/drivers/iio/light/tsl2772.c > > > index be37fcbd4654..44a0b56a558c 100644 > > > --- a/drivers/iio/light/tsl2772.c > > > +++ b/drivers/iio/light/tsl2772.c > > > @@ -986,7 +986,7 @@ static ssize_t in_illuminance0_lux_table_show(struct device *dev, > > > int offset = 0; > > > > > > while (i < TSL2772_MAX_LUX_TABLE_SIZE) { > > > - offset += snprintf(buf + offset, PAGE_SIZE, "%u,%u,", > > > + offset += scnprintf(buf + offset, PAGE_SIZE, "%u,%u,", > > > chip->tsl2772_device_lux[i].ch0, > > > chip->tsl2772_device_lux[i].ch1); > > > if (chip->tsl2772_device_lux[i].ch0 == 0) { > > > @@ -1000,7 +1000,7 @@ static ssize_t in_illuminance0_lux_table_show(struct device *dev, > > > i++; > > > } > > > > > > - offset += snprintf(buf + offset, PAGE_SIZE, "\n"); > > > + offset += scnprintf(buf + offset, PAGE_SIZE, "\n"); > > > return offset; > > > } > > >