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 16 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().
This data is allocated with kzalloc so no data can leak appart
from previous readings.
It is necessary to force the alignment of ts to avoid the padding
on x86_32 being different from 64 bit platorms (it alows for
4 bytes aligned 8 byte types.
Fixes: 06ad7ea10e2b ("max44000: Initial triggered buffer support")
Reported-by: Lars-Peter Clausen <lars@xxxxxxxxxx>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx>
---
drivers/iio/light/max44000.c | 12 ++++++++----
1 file changed, 8 insertions(+), 4 deletions(-)
diff --git a/drivers/iio/light/max44000.c b/drivers/iio/light/max44000.c
index aa8ed1e3e89a..b8e721bced5b 100644
--- a/drivers/iio/light/max44000.c
+++ b/drivers/iio/light/max44000.c
@@ -75,6 +75,11 @@
struct max44000_data {
struct mutex lock;
struct regmap *regmap;
+ /* Ensure naturally aligned timestamp */
+ struct {
+ u16 channels[2];
+ s64 ts __aligned(8);
+ } scan;
};
/* Default scale is set to the minimum of 0.03125 or 1 / (1 << 5) lux */
@@ -488,7 +493,6 @@ static irqreturn_t max44000_trigger_handler(int irq, void *p)
struct iio_poll_func *pf = p;
struct iio_dev *indio_dev = pf->indio_dev;
struct max44000_data *data = iio_priv(indio_dev);
- u16 buf[8]; /* 2x u16 + padding + 8 bytes timestamp */
int index = 0;
unsigned int regval;
int ret;
@@ -498,17 +502,17 @@ static irqreturn_t max44000_trigger_handler(int irq, void *p)
ret = max44000_read_alsval(data);
if (ret < 0)
goto out_unlock;
- buf[index++] = ret;
+ data->scan.channels[index++] = ret;
}
if (test_bit(MAX44000_SCAN_INDEX_PRX, indio_dev->active_scan_mask)) {
ret = regmap_read(data->regmap, MAX44000_REG_PRX_DATA, ®val);
if (ret < 0)
goto out_unlock;
- buf[index] = regval;
+ data->scan.channels[index] = regval;
}
mutex_unlock(&data->lock);
- iio_push_to_buffers_with_timestamp(indio_dev, buf,
+ iio_push_to_buffers_with_timestamp(indio_dev, &data->scan,
iio_get_time_ns(indio_dev));
iio_trigger_notify_done(indio_dev->trig);
return IRQ_HANDLED;
--
2.26.2
