From patchwork Wed Jul 22 15:50:46 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jonathan Cameron X-Patchwork-Id: 11678711 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 4D49514E3 for ; Wed, 22 Jul 2020 15:53:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3325020B1F for ; Wed, 22 Jul 2020 15:53:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1595433204; bh=TmMsXkQQ5gFHuUkqI6kxjNw5ilxRdJnc9DKZ4hNzOvs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=hVKlf1j1V8OFIQYeTRUMGB2QXlIGLgP6wvIAMJ2tArV13Y8P7r+/HkZoYBBkShTZi cn9K6jbkfqr3xSD1vr+KnSrkF8Irwk+g4UgD2GFxPWjH6VXG9swfCqQr3Esf0na8FU fc/lSXBHiOzQClLHBnyqM7vPjZKoiFP4vBQJZjAU= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729096AbgGVPxX (ORCPT ); Wed, 22 Jul 2020 11:53:23 -0400 Received: from mail.kernel.org ([198.145.29.99]:35644 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726427AbgGVPxX (ORCPT ); Wed, 22 Jul 2020 11:53:23 -0400 Received: from localhost.localdomain (cpc149474-cmbg20-2-0-cust94.5-4.cable.virginm.net [82.4.196.95]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 27568207CD; Wed, 22 Jul 2020 15:53:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1595433203; bh=TmMsXkQQ5gFHuUkqI6kxjNw5ilxRdJnc9DKZ4hNzOvs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=tGQf0jj/X++nAdgNUzZjIWYDaim66KvJA6xvU/V/9+8kl4b25g+DSFtaY6tvDu2aQ H6LYg3HUChGycUC/KNOpFk+feYQKl206SnQawuf+38d6O/RQUt+xRG0hS/c2hHDwpw ojOG2CcuhMkDHIQEOK3b3qN63F5H6TiWr1Vg99Z4= From: Jonathan Cameron To: linux-iio@vger.kernel.org Cc: Andy Shevchenko , Lars-Peter Clausen , Peter Meerwald , Jonathan Cameron , Mikko Koivunen Subject: [PATCH v3 10/27] iio:light:rpr0521 Fix timestamp alignment and prevent data leak. Date: Wed, 22 Jul 2020 16:50:46 +0100 Message-Id: <20200722155103.979802-11-jic23@kernel.org> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20200722155103.979802-1-jic23@kernel.org> References: <20200722155103.979802-1-jic23@kernel.org> MIME-Version: 1.0 Sender: linux-iio-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-iio@vger.kernel.org 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(). This data is allocated with kzalloc so no data can leak appart from previous readings and in this case the status byte from the device. The forced alignment of ts is not necessary in this case but it potentially makes the code less fragile. Fixes: e12ffd241c00 ("iio: light: rpr0521 triggered buffer") Cc: Mikko Koivunen Signed-off-by: Jonathan Cameron --- drivers/iio/light/rpr0521.c | 17 +++++++++++++---- 1 file changed, 13 insertions(+), 4 deletions(-) diff --git a/drivers/iio/light/rpr0521.c b/drivers/iio/light/rpr0521.c index aa2972b04833..31224a33bade 100644 --- a/drivers/iio/light/rpr0521.c +++ b/drivers/iio/light/rpr0521.c @@ -194,6 +194,17 @@ struct rpr0521_data { bool pxs_need_dis; struct regmap *regmap; + + /* + * Ensure correct naturally aligned timestamp. + * Note that the read will put garbage data into + * the padding but this should not be a problem + */ + struct { + __le16 channels[3]; + u8 garbage; + s64 ts __aligned(8); + } scan; }; static IIO_CONST_ATTR(in_intensity_scale_available, RPR0521_ALS_SCALE_AVAIL); @@ -449,8 +460,6 @@ static irqreturn_t rpr0521_trigger_consumer_handler(int irq, void *p) struct rpr0521_data *data = iio_priv(indio_dev); int err; - u8 buffer[16]; /* 3 16-bit channels + padding + ts */ - /* Use irq timestamp when reasonable. */ if (iio_trigger_using_own(indio_dev) && data->irq_timestamp) { pf->timestamp = data->irq_timestamp; @@ -461,11 +470,11 @@ static irqreturn_t rpr0521_trigger_consumer_handler(int irq, void *p) pf->timestamp = iio_get_time_ns(indio_dev); err = regmap_bulk_read(data->regmap, RPR0521_REG_PXS_DATA, - &buffer, + data->scan.channels, (3 * 2) + 1); /* 3 * 16-bit + (discarded) int clear reg. */ if (!err) iio_push_to_buffers_with_timestamp(indio_dev, - buffer, pf->timestamp); + &data->scan, pf->timestamp); else dev_err(&data->client->dev, "Trigger consumer can't read from sensor.\n");