On Sun, 7 Jun 2020 16:53:53 +0100
Jonathan Cameron <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 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.
>
> Explicit alignment of ts needed to ensure consistent padding
> on all architectures (particularly x86_32 with it's 4 byte alignment
> of s64)
>
> Fixes: e4a70e3e7d84 ("iio: humidity: add support to hts221 rh/temp combo device")
> Reported-by: Lars-Peter Clausen <lars@xxxxxxxxxx>
> Acked-by: Lorenzo Bianconi <lorenzo@xxxxxxxxxx>
> Signed-off-by: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx>
Applied to the fixes-togreg branch of iio.git and marked for stable.
I'm scooping up all the ones in this series for which I have an ack so
that we can focus on getting remainder reviewed.
Thanks,
Jonathan
> ---
> drivers/iio/humidity/hts221.h | 7 +++++--
> drivers/iio/humidity/hts221_buffer.c | 9 +++++----
> 2 files changed, 10 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/iio/humidity/hts221.h b/drivers/iio/humidity/hts221.h
> index 7c650df77556..721359e226cb 100644
> --- a/drivers/iio/humidity/hts221.h
> +++ b/drivers/iio/humidity/hts221.h
> @@ -14,8 +14,6 @@
>
> #include <linux/iio/iio.h>
>
> -#define HTS221_DATA_SIZE 2
> -
> enum hts221_sensor_type {
> HTS221_SENSOR_H,
> HTS221_SENSOR_T,
> @@ -39,6 +37,11 @@ struct hts221_hw {
>
> bool enabled;
> u8 odr;
> + /* Ensure natural alignment of timestamp */
> + struct {
> + __le16 channels[2];
> + s64 ts __aligned(8);
> + } scan;
> };
>
> extern const struct dev_pm_ops hts221_pm_ops;
> diff --git a/drivers/iio/humidity/hts221_buffer.c b/drivers/iio/humidity/hts221_buffer.c
> index 21c6c160462d..59ede9860185 100644
> --- a/drivers/iio/humidity/hts221_buffer.c
> +++ b/drivers/iio/humidity/hts221_buffer.c
> @@ -160,7 +160,6 @@ static const struct iio_buffer_setup_ops hts221_buffer_ops = {
>
> static irqreturn_t hts221_buffer_handler_thread(int irq, void *p)
> {
> - u8 buffer[ALIGN(2 * HTS221_DATA_SIZE, sizeof(s64)) + sizeof(s64)];
> struct iio_poll_func *pf = p;
> struct iio_dev *iio_dev = pf->indio_dev;
> struct hts221_hw *hw = iio_priv(iio_dev);
> @@ -170,18 +169,20 @@ static irqreturn_t hts221_buffer_handler_thread(int irq, void *p)
> /* humidity data */
> ch = &iio_dev->channels[HTS221_SENSOR_H];
> err = regmap_bulk_read(hw->regmap, ch->address,
> - buffer, HTS221_DATA_SIZE);
> + &hw->scan.channels[0],
> + sizeof(hw->scan.channels[0]));
> if (err < 0)
> goto out;
>
> /* temperature data */
> ch = &iio_dev->channels[HTS221_SENSOR_T];
> err = regmap_bulk_read(hw->regmap, ch->address,
> - buffer + HTS221_DATA_SIZE, HTS221_DATA_SIZE);
> + &hw->scan.channels[1],
> + sizeof(hw->scan.channels[1]));
> if (err < 0)
> goto out;
>
> - iio_push_to_buffers_with_timestamp(iio_dev, buffer,
> + iio_push_to_buffers_with_timestamp(iio_dev, &hw->scan,
> iio_get_time_ns(iio_dev));
>
> out:
