From: Jonathan Cameron Jonathan.Cameron@huawei.com
commit d837a996f57c29a985177bc03b0e599082047f27 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 an 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 apart from previous readings.
A local unsigned int variable is used for the regmap call so it is clear there is no potential issue with writing into the padding of the structure.
Fixes: 3025c8688c1e ("iio: light: add support for UVIS25 sensor") Reported-by: Lars-Peter Clausen lars@metafoo.de Signed-off-by: Jonathan Cameron Jonathan.Cameron@huawei.com Reviewed-by: Alexandru Ardelean alexandru.ardelean@analog.com Acked-by: Lorenzo Bianconi lorenzo@kernel.org Cc: Stable@vger.kernel.org Link: https://lore.kernel.org/r/20200920112742.170751-3-jic23@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/iio/light/st_uvis25.h | 5 +++++ drivers/iio/light/st_uvis25_core.c | 8 +++++--- 2 files changed, 10 insertions(+), 3 deletions(-)
--- a/drivers/iio/light/st_uvis25.h +++ b/drivers/iio/light/st_uvis25.h @@ -27,6 +27,11 @@ struct st_uvis25_hw { struct iio_trigger *trig; bool enabled; int irq; + /* Ensure timestamp is naturally aligned */ + struct { + u8 chan; + s64 ts __aligned(8); + } scan; };
extern const struct dev_pm_ops st_uvis25_pm_ops; --- a/drivers/iio/light/st_uvis25_core.c +++ b/drivers/iio/light/st_uvis25_core.c @@ -234,17 +234,19 @@ static const struct iio_buffer_setup_ops
static irqreturn_t st_uvis25_buffer_handler_thread(int irq, void *p) { - u8 buffer[ALIGN(sizeof(u8), sizeof(s64)) + sizeof(s64)]; struct iio_poll_func *pf = p; struct iio_dev *iio_dev = pf->indio_dev; struct st_uvis25_hw *hw = iio_priv(iio_dev); + unsigned int val; int err;
- err = regmap_read(hw->regmap, ST_UVIS25_REG_OUT_ADDR, (int *)buffer); + err = regmap_read(hw->regmap, ST_UVIS25_REG_OUT_ADDR, &val); if (err < 0) goto out;
- iio_push_to_buffers_with_timestamp(iio_dev, buffer, + hw->scan.chan = val; + + iio_push_to_buffers_with_timestamp(iio_dev, &hw->scan, iio_get_time_ns(iio_dev));
out: