From a661b571e3682705cb402a5cd1e970586a3ec00f Mon Sep 17 00:00:00 2001 From: Jonathan Cameron Date: Wed, 22 Jul 2020 16:50:57 +0100 Subject: iio:adc:ti-adc084s021 Fix alignment and data leak issues. MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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. The force alignment of ts is not strictly necessary in this case but reduces the fragility of the code. Fixes: 3691e5a69449 ("iio: adc: add driver for the ti-adc084s021 chip") Reported-by: Lars-Peter Clausen Cc: Mårten Lindahl Signed-off-by: Jonathan Cameron Reviewed-by: Andy Shevchenko Cc: --- drivers/iio/adc/ti-adc084s021.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/drivers/iio/adc/ti-adc084s021.c b/drivers/iio/adc/ti-adc084s021.c index 9017e1e24273..dfba34834a57 100644 --- a/drivers/iio/adc/ti-adc084s021.c +++ b/drivers/iio/adc/ti-adc084s021.c @@ -26,6 +26,11 @@ struct adc084s021 { struct spi_transfer spi_trans; struct regulator *reg; struct mutex lock; + /* Buffer used to align data */ + struct { + __be16 channels[4]; + s64 ts __aligned(8); + } scan; /* * DMA (thus cache coherency maintenance) requires the * transfer buffers to live in their own cache line. @@ -141,14 +146,13 @@ static irqreturn_t adc084s021_buffer_trigger_handler(int irq, void *pollfunc) struct iio_poll_func *pf = pollfunc; struct iio_dev *indio_dev = pf->indio_dev; struct adc084s021 *adc = iio_priv(indio_dev); - __be16 data[8] = {0}; /* 4 * 16-bit words of data + 8 bytes timestamp */ mutex_lock(&adc->lock); - if (adc084s021_adc_conversion(adc, &data) < 0) + if (adc084s021_adc_conversion(adc, adc->scan.channels) < 0) dev_err(&adc->spi->dev, "Failed to read data\n"); - 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)); mutex_unlock(&adc->lock); iio_trigger_notify_done(indio_dev->trig); -- cgit v1.2.3