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=-13.1 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_GIT autolearn=unavailable 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 936B9C433E8 for ; Wed, 22 Jul 2020 15:53:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 69C5F208E4 for ; Wed, 22 Jul 2020 15:53:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1595433201; bh=bygXAix11Yif9FOMNTJ8h+p55wt+ROUtmFRG85PnGR4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=TVzQZU4Kh7scY3xnSuAH+uTL7/DHhNwjG24b4ksJnYnEqavqlwXkh2hGsw6B9UDTE OJE8oUuUThDGFF+cQj4KtCDApZ+w2Lz7PcC0PV7Zxd1JwcM5AgsQ9KeDPV6FrDJjUY DrzUgJgNe/moH97eg+nudAw9ZkaHF9Z09CVHegsc= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728697AbgGVPxV (ORCPT ); Wed, 22 Jul 2020 11:53:21 -0400 Received: from mail.kernel.org ([198.145.29.99]:35614 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726427AbgGVPxU (ORCPT ); Wed, 22 Jul 2020 11:53:20 -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 5CA80206F5; Wed, 22 Jul 2020 15:53:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1595433200; bh=bygXAix11Yif9FOMNTJ8h+p55wt+ROUtmFRG85PnGR4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=LmjgHCUHKPjaeNrOj/F+ADsQ4rJqULAgrosOZBjZWJYUCicppfRk39gnXE1StVRpQ RtXHf6FCSWBelQCQM3+EZtKrR1d9z+r/r4Ke2wkLFO1Xw8fe3iL/8edMlVhVs54KnD oT95apDhYB7WQUE6XetDWscqHSln7UEhvuAlx0kQ= From: Jonathan Cameron To: linux-iio@vger.kernel.org Cc: Andy Shevchenko , Lars-Peter Clausen , Peter Meerwald , Jonathan Cameron Subject: [PATCH v3 08/27] iio:light:si1145: Fix timestamp alignment and prevent data leak. Date: Wed, 22 Jul 2020 16:50:44 +0100 Message-Id: <20200722155103.979802-9-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 Content-Transfer-Encoding: 8bit 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 24 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 array in the iio_priv() data with alignment explicitly requested. This data is allocated with kzalloc so no data can leak appart from previous readings. Depending on the enabled channels, the location of the timestamp can be at various aligned offsets through the buffer. As such we any use of a structure to enforce this alignment would incorrectly suggest a single location for the timestamp. Fixes: ac45e57f1590 ("iio: light: Add driver for Silabs si1132, si1141/2/3 and si1145/6/7 ambient light, uv index and proximity sensors") Reported-by: Lars-Peter Clausen Cc: Peter Meerwald-Stadler Signed-off-by: Jonathan Cameron --- drivers/iio/light/si1145.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/drivers/iio/light/si1145.c b/drivers/iio/light/si1145.c index 155faaea8c72..e8bdc221d65b 100644 --- a/drivers/iio/light/si1145.c +++ b/drivers/iio/light/si1145.c @@ -179,6 +179,8 @@ struct si1145_data { bool autonomous; struct iio_trigger *trig; int meas_rate; + /* Ensure timestamp will be naturally aligned if present */ + u8 buffer[24] __aligned(8); }; /* @@ -445,7 +447,6 @@ static irqreturn_t si1145_trigger_handler(int irq, void *private) * 6*2 bytes channels data + 4 bytes alignment + * 8 bytes timestamp */ - u8 buffer[24]; int i, j = 0; int ret; u8 irq_status = 0; @@ -478,7 +479,7 @@ static irqreturn_t si1145_trigger_handler(int irq, void *private) ret = i2c_smbus_read_i2c_block_data_or_emulated( data->client, indio_dev->channels[i].address, - sizeof(u16) * run, &buffer[j]); + sizeof(u16) * run, &data->buffer[j]); if (ret < 0) goto done; j += run * sizeof(u16); @@ -493,7 +494,7 @@ static irqreturn_t si1145_trigger_handler(int irq, void *private) goto done; } - iio_push_to_buffers_with_timestamp(indio_dev, buffer, + iio_push_to_buffers_with_timestamp(indio_dev, data->buffer, iio_get_time_ns(indio_dev)); done: -- 2.27.0