From patchwork Wed Jul 22 15:50:47 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jonathan Cameron X-Patchwork-Id: 11678713 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 403C913A4 for ; Wed, 22 Jul 2020 15:53:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2880A20B1F for ; Wed, 22 Jul 2020 15:53:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1595433206; bh=TZ4FEWAjKvmXqgkVVlnaXf+ULLHl8K8W0YsSzflV640=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=ixRMzhNGwrLo+5M3spsmUfNlJO+hhVu5xKhkA+LSUmxTldbhWJsbB6elo0ulRqBCf Y1/0NgItrsh32mRBcED/+W/uQOdvLRfgeWt19QjfXf9nW7eylQkTi068laes5Qds8o 6uQljWUfZ9HmTxmkQeORdMox/Ed+IypsFZ8um0Dw= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729201AbgGVPxZ (ORCPT ); Wed, 22 Jul 2020 11:53:25 -0400 Received: from mail.kernel.org ([198.145.29.99]:35662 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726427AbgGVPxZ (ORCPT ); Wed, 22 Jul 2020 11:53:25 -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 BBFFB20771; Wed, 22 Jul 2020 15:53:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1595433204; bh=TZ4FEWAjKvmXqgkVVlnaXf+ULLHl8K8W0YsSzflV640=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=BQsfQx43RSPWtWCsBn4eIozzwpTJ3IZigMLU737MCM+WGIV6Sm3saFkyr9TXPr7ii W/FOktrsstQztFB6wBabyoemT9vK4tYEjCq5r1nfWrytdJ2fqS5VhDkemN3/sCNLYB 6lzVewp4pX/W41PWpr4VZqI0qwfGySQT3ZFcEI0A= From: Jonathan Cameron To: linux-iio@vger.kernel.org Cc: Andy Shevchenko , Lars-Peter Clausen , Peter Meerwald , Jonathan Cameron , Lorenzo Bianconi Subject: [PATCH v3 11/27] iio:light:st_uvis25 Fix timestamp alignment and prevent data leak. Date: Wed, 22 Jul 2020 16:50:47 +0100 Message-Id: <20200722155103.979802-12-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 apart from previous readings. A local unsigned int variable is used for the regmap call so it is clear there is no potential issue with writing into the padding of the structure. Fixes: 3025c8688c1e ("iio: light: add support for UVIS25 sensor") Reported-by: Lars-Peter Clausen Acked-by: Lorenzo Bianconi Signed-off-by: Jonathan Cameron --- drivers/iio/light/st_uvis25.h | 5 +++++ drivers/iio/light/st_uvis25_core.c | 8 +++++--- 2 files changed, 10 insertions(+), 3 deletions(-) diff --git a/drivers/iio/light/st_uvis25.h b/drivers/iio/light/st_uvis25.h index 78bc56aad129..283086887caf 100644 --- a/drivers/iio/light/st_uvis25.h +++ b/drivers/iio/light/st_uvis25.h @@ -27,6 +27,11 @@ struct st_uvis25_hw { struct iio_trigger *trig; bool enabled; int irq; + /* Ensure timestamp is naturally aligned */ + struct { + u8 chan; + s64 ts __aligned(8); + } scan; }; extern const struct dev_pm_ops st_uvis25_pm_ops; diff --git a/drivers/iio/light/st_uvis25_core.c b/drivers/iio/light/st_uvis25_core.c index a18a82e6bbf5..50d9850256fc 100644 --- a/drivers/iio/light/st_uvis25_core.c +++ b/drivers/iio/light/st_uvis25_core.c @@ -232,17 +232,19 @@ static const struct iio_buffer_setup_ops st_uvis25_buffer_ops = { static irqreturn_t st_uvis25_buffer_handler_thread(int irq, void *p) { - u8 buffer[ALIGN(sizeof(u8), sizeof(s64)) + sizeof(s64)]; struct iio_poll_func *pf = p; struct iio_dev *iio_dev = pf->indio_dev; struct st_uvis25_hw *hw = iio_priv(iio_dev); + unsigned int val; int err; - err = regmap_read(hw->regmap, ST_UVIS25_REG_OUT_ADDR, (int *)buffer); + err = regmap_read(hw->regmap, ST_UVIS25_REG_OUT_ADDR, &val); if (err < 0) goto out; - iio_push_to_buffers_with_timestamp(iio_dev, buffer, + hw->scan.chan = val & 0xFF; + + iio_push_to_buffers_with_timestamp(iio_dev, &hw->scan, iio_get_time_ns(iio_dev)); out: