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iio:health:afe4404 Fix timestamp alignment and prevent data leak. 

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: 87aec56e27 ("iio: health: Add driver for the TI AFE4404 heart monitor")
Reported-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Acked-by: Andrew F. Davis <afd@ti.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
This commit is contained in:
Jonathan Cameron 2020-05-17 18:29:57 +01:00
parent 3f9c6d3879
commit f88ecccac4
1 changed files with 5 additions and 3 deletions
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8
drivers/iio/health/afe4404.c
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@ -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);