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=-11.6 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,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 14782C433DF for ; Sun, 9 Aug 2020 17:30:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E02C4206E9 for ; Sun, 9 Aug 2020 17:30:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1596994244; bh=Z49o3L+2ZuGYhTRk4b1a+8Ss6BqLtJO8clvwV8JNrOE=; h=Date:From:To:Cc:Subject:In-Reply-To:References:List-ID:From; b=ADfB5h9NOdmfXgk7NKIEHKmVaye3hMzUSez/twMhaquSzblX7eesTQkaoqCrjRWGd w9hAcwl0IdyFfZLgpA2vi6txcp2f9jd2fgFr86udBOXd01BTou7fKjUwEHmJ1vdJhQ 2G7YhSrAkLNXyxzr9ZnlaLpd6D8Gtahp40Lp27K4= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726229AbgHIRao (ORCPT ); Sun, 9 Aug 2020 13:30:44 -0400 Received: from mail.kernel.org ([198.145.29.99]:58358 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726175AbgHIRao (ORCPT ); Sun, 9 Aug 2020 13:30:44 -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 077E2206CD; Sun, 9 Aug 2020 17:30:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1596994243; bh=Z49o3L+2ZuGYhTRk4b1a+8Ss6BqLtJO8clvwV8JNrOE=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=QY6SJUr4qQIxXMKvFXFPqzmfya90oN5NiArnemclbIsl+iPij/x1chFSu8sIevTRe qj2ThtjMRleEhhdtBSuO0dw8QqrTDd1Zq3xxvrMHjAPLqgnIDlGLryljvst+r6pETx 53WNMF4FFalFjdB0wmV1wOHkMu8BAkjrifzevJ88= Date: Sun, 9 Aug 2020 18:30:39 +0100 From: Jonathan Cameron To: linux-iio@vger.kernel.org Cc: Andy Shevchenko , Lars-Peter Clausen , Peter Meerwald , Jonathan Cameron , Gregor Boirie , Andy Shevchenko , Linus Walleij Subject: Re: [PATCH v3 13/27] iio:magnetometer:ak8975 Fix alignment and data leak issues. Message-ID: <20200809183039.0db00485@archlinux> In-Reply-To: <20200722155103.979802-14-jic23@kernel.org> References: <20200722155103.979802-1-jic23@kernel.org> <20200722155103.979802-14-jic23@kernel.org> X-Mailer: Claws Mail 3.17.6 (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, 22 Jul 2020 16:50:49 +0100 Jonathan Cameron wrote: > From: Jonathan Cameron > > One of a class of bugs pointed out by Lars in a recent review. > iio_push_to_buffers_with_timestamp assumes the buffer used is aligned > to the size of the timestamp (8 bytes). This is not guaranteed in > this driver which uses an array of smaller elements on the stack. > As Lars also noted this anti pattern can involve a leak of data to > userspace and that indeed can happen here. We close both issues by > moving to a suitable structure in the iio_priv() data. > > This data is allocated with kzalloc so no data can leak apart from > previous readings. > > The explicit alignment of ts is not necessary in this case as by > coincidence the padding will end up the same, however I consider > it to make the code less fragile and have included it. > > Fixes: bc11ca4a0b84 ("iio:magnetometer:ak8975: triggered buffer support") > Reported-by: Lars-Peter Clausen > Cc: Gregor Boirie > Cc: Andy Shevchenko > Cc: Linus Walleij > Signed-off-by: Jonathan Cameron Applied and marked for stable. Thanks, Jonathan > --- > drivers/iio/magnetometer/ak8975.c | 16 +++++++++++----- > 1 file changed, 11 insertions(+), 5 deletions(-) > > diff --git a/drivers/iio/magnetometer/ak8975.c b/drivers/iio/magnetometer/ak8975.c > index 03d71f796177..623766ff800b 100644 > --- a/drivers/iio/magnetometer/ak8975.c > +++ b/drivers/iio/magnetometer/ak8975.c > @@ -366,6 +366,12 @@ struct ak8975_data { > struct iio_mount_matrix orientation; > struct regulator *vdd; > struct regulator *vid; > + > + /* Ensure natural alignment of timestamp */ > + struct { > + s16 channels[3]; > + s64 ts __aligned(8); > + } scan; > }; > > /* Enable attached power regulator if any. */ > @@ -793,7 +799,6 @@ static void ak8975_fill_buffer(struct iio_dev *indio_dev) > const struct i2c_client *client = data->client; > const struct ak_def *def = data->def; > int ret; > - s16 buff[8]; /* 3 x 16 bits axis values + 1 aligned 64 bits timestamp */ > __le16 fval[3]; > > mutex_lock(&data->lock); > @@ -816,12 +821,13 @@ static void ak8975_fill_buffer(struct iio_dev *indio_dev) > mutex_unlock(&data->lock); > > /* Clamp to valid range. */ > - buff[0] = clamp_t(s16, le16_to_cpu(fval[0]), -def->range, def->range); > - buff[1] = clamp_t(s16, le16_to_cpu(fval[1]), -def->range, def->range); > - buff[2] = clamp_t(s16, le16_to_cpu(fval[2]), -def->range, def->range); > + data->scan.channels[0] = clamp_t(s16, le16_to_cpu(fval[0]), -def->range, def->range); > + data->scan.channels[1] = clamp_t(s16, le16_to_cpu(fval[1]), -def->range, def->range); > + data->scan.channels[2] = clamp_t(s16, le16_to_cpu(fval[2]), -def->range, def->range); > > - iio_push_to_buffers_with_timestamp(indio_dev, buff, > + iio_push_to_buffers_with_timestamp(indio_dev, &data->scan, > iio_get_time_ns(indio_dev)); > + > return; > > unlock: