From patchwork Sun Jun 7 15:53:46 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jonathan Cameron X-Patchwork-Id: 11591679 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 7F4FA912 for ; Sun, 7 Jun 2020 15:56:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 69698207C3 for ; Sun, 7 Jun 2020 15:56:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1591545389; bh=duArOxpewVlEIEs0Kj8syK3wzNGOBAJ/uJ57SD/1F7w=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=YoGhsX0YbeHQ+q5YeRiBNLJKEBdlj/G1xoTP521N5y03vCDG/VSngcYX70XvJ9RK4 EOINB6phIsT/ZCZGR6qtzJCCGQETplCDSHalEKXUK4LrJ2qFbFbyk6nyOZSN/j0yfN TpG95ERWw9GS8QijxxDtmoGySyD5qo2vMKNjYmj0= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726698AbgFGP42 (ORCPT ); Sun, 7 Jun 2020 11:56:28 -0400 Received: from mail.kernel.org ([198.145.29.99]:57342 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726631AbgFGP42 (ORCPT ); Sun, 7 Jun 2020 11:56:28 -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 347CC2078C; Sun, 7 Jun 2020 15:56:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1591545388; bh=duArOxpewVlEIEs0Kj8syK3wzNGOBAJ/uJ57SD/1F7w=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=SDPwBA/D/fHbpYl324o55ZsG5hDojQZySUQyEBMVuNBN/4YW8Cr/l9P1ffeochIsW F+pl6Xozp6h26P8PjdJUI6fdQPnLQ0eP5V/I3YTyVEU7D0DcekzLUMEh1hT1Ws6rVr 35QBjRigROUrSH61TvKNBdSPwUqwl/Mm6L9wpKHs= From: Jonathan Cameron To: linux-iio@vger.kernel.org Cc: Andy Shevchenko , Jonathan Cameron , Mikko Koivunen Subject: [PATCH 10/32] iio:light:rpr0521 Fix timestamp alignment and prevent data leak. Date: Sun, 7 Jun 2020 16:53:46 +0100 Message-Id: <20200607155408.958437-11-jic23@kernel.org> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20200607155408.958437-1-jic23@kernel.org> References: <20200607155408.958437-1-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 c20fbc730d65..66f22ea3d68a 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");