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| author | Jonathan Cameron <Jonathan.Cameron@huawei.com> | 2020-07-22 16:50:38 +0100 |
|---|---|---|
| committer | Jonathan Cameron <Jonathan.Cameron@huawei.com> | 2020-08-22 11:38:48 +0100 |
| commit | 89226a296d816727405d3fea684ef69e7d388bd8 (patch) | |
| tree | a39833ddb5e0497f250188c33304a422a4ec5012 /drivers/iio/accel/mma8452.c | |
| parent | 95ad67577de4ea08eb8e441394e698aa4addcc0b (diff) | |
| download | linux-89226a296d816727405d3fea684ef69e7d388bd8.tar.bz2 | |
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@metafoo.de>
Cc: Peter Meerwald <pmeerw@pmeerw.net>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: <Stable@vger.kernel.org>
Diffstat (limited to 'drivers/iio/accel/mma8452.c')
| -rw-r--r-- | drivers/iio/accel/mma8452.c | 11 |
1 files 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: |