linux-kernel - [PATCH 4.9 32/32] iio:magnetometer:mag3110: Fix alignment and data leak issues.

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20210107140829.394192914@linuxfoundation.org>
Date:   Thu,  7 Jan 2021 15:16:52 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Lars-Peter Clausen <lars@...afoo.de>,
        Jonathan Cameron <Jonathan.Cameron@...wei.com>,
        Alexandru Ardelean <alexandru.ardelean@...log.com>,
        Stable@...r.kernel.org,
        Sudip Mukherjee <sudipm.mukherjee@...il.com>
Subject: [PATCH 4.9 32/32] iio:magnetometer:mag3110: Fix alignment and data leak issues.

From: Jonathan Cameron <Jonathan.Cameron@...wei.com>

commit 89deb1334252ea4a8491d47654811e28b0790364 upstream

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() data.
This data is allocated with kzalloc() so no data can leak apart from
previous readings.

The explicit alignment of ts is not necessary in this case but
does make the code slightly less fragile so I have included it.

Fixes: 39631b5f9584 ("iio: Add Freescale mag3110 magnetometer driver")
Reported-by: Lars-Peter Clausen <lars@...afoo.de>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@...wei.com>
Reviewed-by: Alexandru Ardelean <alexandru.ardelean@...log.com>
Cc: <Stable@...r.kernel.org>
Link: https://lore.kernel.org/r/20200920112742.170751-4-jic23@kernel.org
[sudip: adjust context]
Signed-off-by: Sudip Mukherjee <sudipm.mukherjee@...il.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/iio/magnetometer/mag3110.c |   13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

--- a/drivers/iio/magnetometer/mag3110.c
+++ b/drivers/iio/magnetometer/mag3110.c
@@ -52,6 +52,12 @@ struct mag3110_data {
 	struct i2c_client *client;
 	struct mutex lock;
 	u8 ctrl_reg1;
+	/* Ensure natural alignment of timestamp */
+	struct {
+		__be16 channels[3];
+		u8 temperature;
+		s64 ts __aligned(8);
+	} scan;
 };
 
 static int mag3110_request(struct mag3110_data *data)
@@ -262,10 +268,9 @@ static irqreturn_t mag3110_trigger_handl
 	struct iio_poll_func *pf = p;
 	struct iio_dev *indio_dev = pf->indio_dev;
 	struct mag3110_data *data = iio_priv(indio_dev);
-	u8 buffer[16]; /* 3 16-bit channels + 1 byte temp + padding + ts */
 	int ret;
 
-	ret = mag3110_read(data, (__be16 *) buffer);
+	ret = mag3110_read(data, data->scan.channels);
 	if (ret < 0)
 		goto done;
 
@@ -274,10 +279,10 @@ static irqreturn_t mag3110_trigger_handl
 			MAG3110_DIE_TEMP);
 		if (ret < 0)
 			goto done;
-		buffer[6] = ret;
+		data->scan.temperature = ret;
 	}
 
-	iio_push_to_buffers_with_timestamp(indio_dev, buffer,
+	iio_push_to_buffers_with_timestamp(indio_dev, &data->scan,
 		iio_get_time_ns(indio_dev));
 
 done: