From patchwork Sun Jun 7 15:53:39 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jonathan Cameron X-Patchwork-Id: 11591665 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 582C8912 for ; Sun, 7 Jun 2020 15:56:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 37CF12076A for ; Sun, 7 Jun 2020 15:56:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1591545380; bh=9kiqwp1rYM2CUyFROitiUwFxoc+sCvxLnU5Nt/Os72M=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=Uckkqq/c+tR0FFaTeR7j1f95bh5Bu21aL3HR5he31r/PlOIAlBwddYn2tDbcX3Ra9 iLU6iiBB5h9O2/24nGZQ0ba66CsfFG04kX3DuhPzRYFDHpqcVPWa8YMURPeHimfMJ4 SnFizDkj+2TXCM5v1dUxndkerdQd2Ll8B84coMSk= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726663AbgFGP4T (ORCPT ); Sun, 7 Jun 2020 11:56:19 -0400 Received: from mail.kernel.org ([198.145.29.99]:57232 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726631AbgFGP4T (ORCPT ); Sun, 7 Jun 2020 11:56:19 -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 D4A2620723; Sun, 7 Jun 2020 15:56:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1591545378; bh=9kiqwp1rYM2CUyFROitiUwFxoc+sCvxLnU5Nt/Os72M=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=W9EcXawmQgt4Nmz00IWf8X9PHgmyBW8qb/9WvM97Eu013gecuMFGIf8OB82R9BnPS ndiezIRyDlM27ZcmRyi1BasEs9qWRMRvhWaHFI/yK95V+u9A/px/pDIUzR7H/Pu/CY +roEldfiHaA2jsC5B0HqhevnRdDFqQGacv9tOGa0= From: Jonathan Cameron To: linux-iio@vger.kernel.org Cc: Andy Shevchenko , Jonathan Cameron , Lars-Peter Clausen , Srinivas Pandruvada Subject: [PATCH 03/32] iio:accel:bmc150-accel: Fix timestamp alignment and prevent data leak. Date: Sun, 7 Jun 2020 16:53:39 +0100 Message-Id: <20200607155408.958437-4-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 a 16 byte 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 with alignment ensured by use of an explicit c structure. This data is allocated with kzalloc so no data can leak appart from previous readings. Fixes tag is beyond some major refactoring so likely manual backporting would be needed to get that far back. Whilst the force alignment of the ts is not strictly necessary, it does make the code less fragile. Fixes: 3bbec9773389 ("iio: bmc150_accel: add support for hardware fifo") Reported-by: Lars-Peter Clausen Cc: Srinivas Pandruvada Signed-off-by: Jonathan Cameron --- drivers/iio/accel/bmc150-accel-core.c | 15 ++++++++++++--- 1 file changed, 12 insertions(+), 3 deletions(-) diff --git a/drivers/iio/accel/bmc150-accel-core.c b/drivers/iio/accel/bmc150-accel-core.c index 8f60d0727ee8..049f2632cf7a 100644 --- a/drivers/iio/accel/bmc150-accel-core.c +++ b/drivers/iio/accel/bmc150-accel-core.c @@ -189,6 +189,14 @@ struct bmc150_accel_data { struct mutex mutex; u8 fifo_mode, watermark; s16 buffer[8]; + /* + * Ensure there is sufficient space and correct alignment for + * the timestamp if enabled + */ + struct { + __le16 channels[3]; + s64 ts __aligned(8); + } scan; u8 bw_bits; u32 slope_dur; u32 slope_thres; @@ -922,15 +930,16 @@ static int __bmc150_accel_fifo_flush(struct iio_dev *indio_dev, * now. */ for (i = 0; i < count; i++) { - u16 sample[8]; int j, bit; j = 0; for_each_set_bit(bit, indio_dev->active_scan_mask, indio_dev->masklength) - memcpy(&sample[j++], &buffer[i * 3 + bit], 2); + memcpy(&data->scan.channels[j++], &buffer[i * 3 + bit], + 2); - iio_push_to_buffers_with_timestamp(indio_dev, sample, tstamp); + iio_push_to_buffers_with_timestamp(indio_dev, &data->scan, + tstamp); tstamp += sample_period; }