From: Jonathan Cameron Jonathan.Cameron@huawei.com
commit 523628852a5f5f34a15252b2634d0498d3cfb347 upstream.
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@metafoo.de Signed-off-by: Jonathan Cameron Jonathan.Cameron@huawei.com Reviewed-by: Andy Shevchenko andy.shevchenko@gmail.com Cc: Stable@vger.kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/iio/light/max44000.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-)
--- a/drivers/iio/light/max44000.c +++ b/drivers/iio/light/max44000.c @@ -78,6 +78,11 @@ 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 */ @@ -492,7 +497,6 @@ static irqreturn_t max44000_trigger_hand 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; @@ -502,17 +506,17 @@ static irqreturn_t max44000_trigger_hand 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;