From: Jonathan Cameron Jonathan.Cameron@huawei.com
commit db8f06d97ec284dc018e2e4890d2e5035fde8630 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() data.
This data is allocated with kzalloc so no data can leak apart from previous readings.
The explicit alignment of ts is necessary to ensure correct padding on architectures where s64 is only 4 bytes aligned such as x86_32.
Fixes: a9e9c7153e96 ("iio: adc: add max1117/max1118/max1119 ADC driver") Reported-by: Lars-Peter Clausen lars@metafoo.de Cc: Akinobu Mita akinobu.mita@gmail.com 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/adc/max1118.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-)
--- a/drivers/iio/adc/max1118.c +++ b/drivers/iio/adc/max1118.c @@ -35,6 +35,11 @@ struct max1118 { struct spi_device *spi; struct mutex lock; struct regulator *reg; + /* Ensure natural alignment of buffer elements */ + struct { + u8 channels[2]; + s64 ts __aligned(8); + } scan;
u8 data ____cacheline_aligned; }; @@ -159,7 +164,6 @@ static irqreturn_t max1118_trigger_handl struct iio_poll_func *pf = p; struct iio_dev *indio_dev = pf->indio_dev; struct max1118 *adc = iio_priv(indio_dev); - u8 data[16] = { }; /* 2x 8-bit ADC data + padding + 8 bytes timestamp */ int scan_index; int i = 0;
@@ -177,10 +181,10 @@ static irqreturn_t max1118_trigger_handl goto out; }
- data[i] = ret; + adc->scan.channels[i] = ret; i++; } - iio_push_to_buffers_with_timestamp(indio_dev, data, + iio_push_to_buffers_with_timestamp(indio_dev, &adc->scan, iio_get_time_ns(indio_dev)); out: mutex_unlock(&adc->lock);