On 5/17/20 1:29 PM, 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 32 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: eec96d1e2d31 ("iio: health: Add driver for the TI AFE4403 heart monitor")
> Reported-by: Lars-Peter Clausen <lars@xxxxxxxxxx>
> Signed-off-by: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx>
> Cc: Andrew F. Davis <afd@xxxxxx>
> ---
> drivers/iio/health/afe4403.c | 9 ++++++---
> 1 file changed, 6 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/iio/health/afe4403.c b/drivers/iio/health/afe4403.c
> index e9f87e42ff4f..a3507624b30f 100644
> --- a/drivers/iio/health/afe4403.c
> +++ b/drivers/iio/health/afe4403.c
> @@ -65,6 +65,7 @@ static const struct reg_field afe4403_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 data layout to push into IIO buffer.
> */
> struct afe4403_data {
> struct device *dev;
> @@ -74,6 +75,8 @@ struct afe4403_data {
> struct regulator *regulator;
> struct iio_trigger *trig;
> int irq;
> + /* Ensure suitable alignment for timestamp */
> + s32 buffer[8] __aligned(8);
One of those fancy structs with the timestamp specified would be nice
here like the other patches. IIRC we have 6 s32 channels, plus a s64 ts.
Other than that everything looks good.
Andrew
> };
>
> enum afe4403_chan_id {
> @@ -309,7 +312,6 @@ static irqreturn_t afe4403_trigger_handler(int irq, void *private)
> struct iio_dev *indio_dev = pf->indio_dev;
> struct afe4403_data *afe = iio_priv(indio_dev);
> int ret, bit, i = 0;
> - s32 buffer[8];
> u8 tx[4] = {AFE440X_CONTROL0, 0x0, 0x0, AFE440X_CONTROL0_READ};
> u8 rx[3];
>
> @@ -326,7 +328,7 @@ static irqreturn_t afe4403_trigger_handler(int irq, void *private)
> if (ret)
> goto err;
>
> - buffer[i++] = get_unaligned_be24(&rx[0]);
> + afe->buffer[i++] = get_unaligned_be24(&rx[0]);
> }
>
> /* Disable reading from the device */
> @@ -335,7 +337,8 @@ static irqreturn_t afe4403_trigger_handler(int irq, void *private)
> 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);
>
>
