On Sun, 17 May 2020 18:29:57 +0100
jic23@xxxxxxxxxx wrote:
> From: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx>
>
> 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 40 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 structure in the iio_priv() data with alignment
> explicitly requested. This data is allocated with kzalloc so no
> data can leak appart from previous readings.
>
> Fixes: 87aec56e27ef ("iio: health: Add driver for the TI AFE4404 heart monitor")
> Reported-by: Lars-Peter Clausen <lars@xxxxxxxxxx>
> Signed-off-by: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx>
> Cc: Andrew F. Davis <afd@xxxxxx>
Applied to the fixes-togreg branch of iio.git and marked for stable.
Thanks,
Jonathan
> ---
> drivers/iio/health/afe4404.c | 8 +++++---
> 1 file changed, 5 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/iio/health/afe4404.c b/drivers/iio/health/afe4404.c
> index e728bbb21ca8..cebb1fd4d0b1 100644
> --- a/drivers/iio/health/afe4404.c
> +++ b/drivers/iio/health/afe4404.c
> @@ -83,6 +83,7 @@ static const struct reg_field afe4404_reg_fields[] = {
> * @regulator: Pointer to the regulator for the IC
> * @trig: IIO trigger for this device
> * @irq: ADC_RDY line interrupt number
> + * @buffer: Used to construct a scan to push to the iio buffer.
> */
> struct afe4404_data {
> struct device *dev;
> @@ -91,6 +92,7 @@ struct afe4404_data {
> struct regulator *regulator;
> struct iio_trigger *trig;
> int irq;
> + s32 buffer[10] __aligned(8);
> };
>
> enum afe4404_chan_id {
> @@ -328,17 +330,17 @@ static irqreturn_t afe4404_trigger_handler(int irq, void *private)
> struct iio_dev *indio_dev = pf->indio_dev;
> struct afe4404_data *afe = iio_priv(indio_dev);
> int ret, bit, i = 0;
> - s32 buffer[10];
>
> for_each_set_bit(bit, indio_dev->active_scan_mask,
> indio_dev->masklength) {
> ret = regmap_read(afe->regmap, afe4404_channel_values[bit],
> - &buffer[i++]);
> + &afe->buffer[i++]);
> if (ret)
> goto err;
> }
>
> - iio_push_to_buffers_with_timestamp(indio_dev, buffer, pf->timestamp);
> + iio_push_to_buffers_with_timestamp(indio_dev, afe->buffer,
> + pf->timestamp);
> err:
> iio_trigger_notify_done(indio_dev->trig);
>
