This is a note to let you know that I've just added the patch titled
iio:accel:mma8452: Fix timestamp alignment and prevent data leak.
to my staging git tree which can be found at
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging.git
in the staging-linus branch.
The patch will show up in the next release of the linux-next tree
(usually sometime within the next 24 hours during the week.)
The patch will hopefully also be merged in Linus's tree for the
next -rc kernel release.
If you have any questions about this process, please let me know.
>From 89226a296d816727405d3fea684ef69e7d388bd8 Mon Sep 17 00:00:00 2001
From: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx>
Date: Wed, 22 Jul 2020 16:50:38 +0100
Subject: iio:accel:mma8452: Fix timestamp alignment and prevent data leak.
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 u8 array 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.
The additional forcing of the 8 byte alignment of the timestamp
is not strictly necessary but makes the code less fragile by
making this explicit.
Fixes: c7eeea93ac60 ("iio: Add Freescale MMA8452Q 3-axis accelerometer driver")
Reported-by: Lars-Peter Clausen <lars@xxxxxxxxxx>
Cc: Peter Meerwald <pmeerw@xxxxxxxxxx>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx>
Reviewed-by: Andy Shevchenko <andy.shevchenko@xxxxxxxxx>
Cc: <Stable@xxxxxxxxxxxxxxx>
---
drivers/iio/accel/mma8452.c | 11 ++++++++---
1 file changed, 8 insertions(+), 3 deletions(-)
diff --git a/drivers/iio/accel/mma8452.c b/drivers/iio/accel/mma8452.c
index ba27f8673131..1cf2b5db26ca 100644
--- a/drivers/iio/accel/mma8452.c
+++ b/drivers/iio/accel/mma8452.c
@@ -110,6 +110,12 @@ struct mma8452_data {
int sleep_val;
struct regulator *vdd_reg;
struct regulator *vddio_reg;
+
+ /* Ensure correct alignment of time stamp when present */
+ struct {
+ __be16 channels[3];
+ s64 ts __aligned(8);
+ } buffer;
};
/**
@@ -1091,14 +1097,13 @@ static irqreturn_t mma8452_trigger_handler(int irq, void *p)
struct iio_poll_func *pf = p;
struct iio_dev *indio_dev = pf->indio_dev;
struct mma8452_data *data = iio_priv(indio_dev);
- u8 buffer[16]; /* 3 16-bit channels + padding + ts */
int ret;
- ret = mma8452_read(data, (__be16 *)buffer);
+ ret = mma8452_read(data, data->buffer.channels);
if (ret < 0)
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:
--
2.28.0
