From: Jonathan Cameron Jonathan.Cameron@huawei.com
commit 89226a296d816727405d3fea684ef69e7d388bd8 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 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 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/iio/accel/mma8452.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-)
--- a/drivers/iio/accel/mma8452.c +++ b/drivers/iio/accel/mma8452.c @@ -96,6 +96,12 @@ struct mma8452_data { u8 ctrl_reg1; u8 data_cfg; const struct mma_chip_info *chip_info; + + /* Ensure correct alignment of time stamp when present */ + struct { + __be16 channels[3]; + s64 ts __aligned(8); + } buffer; };
/** @@ -700,14 +706,13 @@ static irqreturn_t mma8452_trigger_handl 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());
done: