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 B6C2BC2BB1D for ; Sun, 15 Mar 2020 09:54:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8B0BB2072A for ; Sun, 15 Mar 2020 09:54:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1584266091; bh=K8wnhNFEIYULB/96Krs65zMXAmqNPB09nyxJvLsiISA=; h=Date:From:To:Cc:Subject:In-Reply-To:References:List-ID:From; b=uBlqFBrbRC9GXYC1bdTRpqs0InHGlFkt5HPZ3bBkMT70LjEz9KKp2Kp3/xqRU3wHp 3k4VQSlz0Fb/3BJNkidbj7Pho68Czu+fj4euE0gDH5IscO1FkxGXhmnkeD1KeaEFXU QXjo6aIHecdlvd3Iw70RLBbYKCGhxr0JH5PYJdrs= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728173AbgCOJyv (ORCPT ); Sun, 15 Mar 2020 05:54:51 -0400 Received: from mail.kernel.org ([198.145.29.99]:45088 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728159AbgCOJyv (ORCPT ); Sun, 15 Mar 2020 05:54:51 -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 D89E8206EB; Sun, 15 Mar 2020 09:54:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1584266090; bh=K8wnhNFEIYULB/96Krs65zMXAmqNPB09nyxJvLsiISA=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=kJ33sIgpvurzUGqpo+OWfxdHlWY+vLCIcAR8rOjBeINSzf9ED31QaJu6mr/go1Yp0 tfvdQiIApPwMRVXgXzLahTWvj9paKpWFWkms5lZHw7ucDv8MjDghhBpdVies/oMdWq Uc+HarDNsIEOTAS0yLh/96kVIkOz26WmzEZlZlXM= Date: Sun, 15 Mar 2020 09:54:46 +0000 From: Jonathan Cameron To: Takashi Iwai Cc: linux-iio@vger.kernel.org Subject: Re: [PATCH 1/2] iio: core: Use scnprintf() for avoiding potential buffer overflow Message-ID: <20200315095446.4f2aa451@archlinux> In-Reply-To: <20200311074325.7922-2-tiwai@suse.de> References: <20200311074325.7922-1-tiwai@suse.de> <20200311074325.7922-2-tiwai@suse.de> 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 Wed, 11 Mar 2020 08:43:24 +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(). Hmm. This is definitely in the somewhat theoretical bug category, but given it can be called to print a list of values that is defined in a driver, fair enough - it's good protection. I'm not going to rush this in given we don't have any drivers that are known to run into this. Hence I've queued it up for the togreg branch of iio.git targeting the merge window rather than as a fix. Thanks, Jonathan > > Signed-off-by: Takashi Iwai > --- > drivers/iio/industrialio-core.c | 34 +++++++++++++++++----------------- > 1 file changed, 17 insertions(+), 17 deletions(-) > > diff --git a/drivers/iio/industrialio-core.c b/drivers/iio/industrialio-core.c > index 65ff0d067018..197006b5d5c2 100644 > --- a/drivers/iio/industrialio-core.c > +++ b/drivers/iio/industrialio-core.c > @@ -559,46 +559,46 @@ static ssize_t __iio_format_value(char *buf, size_t len, unsigned int type, > > switch (type) { > case IIO_VAL_INT: > - return snprintf(buf, len, "%d", vals[0]); > + return scnprintf(buf, len, "%d", vals[0]); > case IIO_VAL_INT_PLUS_MICRO_DB: > scale_db = true; > /* fall through */ > case IIO_VAL_INT_PLUS_MICRO: > if (vals[1] < 0) > - return snprintf(buf, len, "-%d.%06u%s", abs(vals[0]), > + return scnprintf(buf, len, "-%d.%06u%s", abs(vals[0]), > -vals[1], scale_db ? " dB" : ""); > else > - return snprintf(buf, len, "%d.%06u%s", vals[0], vals[1], > + return scnprintf(buf, len, "%d.%06u%s", vals[0], vals[1], > scale_db ? " dB" : ""); > case IIO_VAL_INT_PLUS_NANO: > if (vals[1] < 0) > - return snprintf(buf, len, "-%d.%09u", abs(vals[0]), > + return scnprintf(buf, len, "-%d.%09u", abs(vals[0]), > -vals[1]); > else > - return snprintf(buf, len, "%d.%09u", vals[0], vals[1]); > + return scnprintf(buf, len, "%d.%09u", vals[0], vals[1]); > case IIO_VAL_FRACTIONAL: > tmp = div_s64((s64)vals[0] * 1000000000LL, vals[1]); > tmp1 = vals[1]; > tmp0 = (int)div_s64_rem(tmp, 1000000000, &tmp1); > - return snprintf(buf, len, "%d.%09u", tmp0, abs(tmp1)); > + return scnprintf(buf, len, "%d.%09u", tmp0, abs(tmp1)); > case IIO_VAL_FRACTIONAL_LOG2: > tmp = shift_right((s64)vals[0] * 1000000000LL, vals[1]); > tmp0 = (int)div_s64_rem(tmp, 1000000000LL, &tmp1); > - return snprintf(buf, len, "%d.%09u", tmp0, abs(tmp1)); > + return scnprintf(buf, len, "%d.%09u", tmp0, abs(tmp1)); > case IIO_VAL_INT_MULTIPLE: > { > int i; > int l = 0; > > for (i = 0; i < size; ++i) { > - l += snprintf(&buf[l], len - l, "%d ", vals[i]); > + l += scnprintf(&buf[l], len - l, "%d ", vals[i]); > if (l >= len) > break; > } > return l; > } > case IIO_VAL_CHAR: > - return snprintf(buf, len, "%c", (char)vals[0]); > + return scnprintf(buf, len, "%c", (char)vals[0]); > default: > return 0; > } > @@ -669,10 +669,10 @@ static ssize_t iio_format_avail_list(char *buf, const int *vals, > if (len >= PAGE_SIZE) > return -EFBIG; > if (i < length - 1) > - len += snprintf(buf + len, PAGE_SIZE - len, > + len += scnprintf(buf + len, PAGE_SIZE - len, > " "); > else > - len += snprintf(buf + len, PAGE_SIZE - len, > + len += scnprintf(buf + len, PAGE_SIZE - len, > "\n"); > if (len >= PAGE_SIZE) > return -EFBIG; > @@ -685,10 +685,10 @@ static ssize_t iio_format_avail_list(char *buf, const int *vals, > if (len >= PAGE_SIZE) > return -EFBIG; > if (i < length / 2 - 1) > - len += snprintf(buf + len, PAGE_SIZE - len, > + len += scnprintf(buf + len, PAGE_SIZE - len, > " "); > else > - len += snprintf(buf + len, PAGE_SIZE - len, > + len += scnprintf(buf + len, PAGE_SIZE - len, > "\n"); > if (len >= PAGE_SIZE) > return -EFBIG; > @@ -712,10 +712,10 @@ static ssize_t iio_format_avail_range(char *buf, const int *vals, int type) > if (len >= PAGE_SIZE) > return -EFBIG; > if (i < 2) > - len += snprintf(buf + len, PAGE_SIZE - len, > + len += scnprintf(buf + len, PAGE_SIZE - len, > " "); > else > - len += snprintf(buf + len, PAGE_SIZE - len, > + len += scnprintf(buf + len, PAGE_SIZE - len, > "]\n"); > if (len >= PAGE_SIZE) > return -EFBIG; > @@ -728,10 +728,10 @@ static ssize_t iio_format_avail_range(char *buf, const int *vals, int type) > if (len >= PAGE_SIZE) > return -EFBIG; > if (i < 2) > - len += snprintf(buf + len, PAGE_SIZE - len, > + len += scnprintf(buf + len, PAGE_SIZE - len, > " "); > else > - len += snprintf(buf + len, PAGE_SIZE - len, > + len += scnprintf(buf + len, PAGE_SIZE - len, > "]\n"); > if (len >= PAGE_SIZE) > return -EFBIG;