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);
};
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);
--
2.26.2
