From: Jonathan Cameron Jonathan.Cameron@huawei.com
commit 39e91f3be4cba51c1560bcda3a343ed1f64dc916 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.
We fix this 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 apart from previous readings. Note that previously no data could leak 'including' previous readings but I don't think it is an issue to potentially leak them like this now does.
In this case the postioning of the timestamp is depends on what other channels are enabled. As such we cannot use a structure to make the alignment explicit as it would be missleading by suggesting only one possible location for the timestamp.
Fixes: 815bbc87462a ("iio: ti-adc0832: add 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: Akinobu Mita akinobu.mita@gmail.com Cc: Stable@vger.kernel.org Link: https://lore.kernel.org/r/20200722155103.979802-25-jic23@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/iio/adc/ti-adc0832.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-)
--- a/drivers/iio/adc/ti-adc0832.c +++ b/drivers/iio/adc/ti-adc0832.c @@ -31,6 +31,12 @@ struct adc0832 { struct regulator *reg; struct mutex lock; u8 mux_bits; + /* + * Max size needed: 16x 1 byte ADC data + 8 bytes timestamp + * May be shorter if not all channels are enabled subject + * to the timestamp remaining 8 byte aligned. + */ + u8 data[24] __aligned(8);
u8 tx_buf[2] ____cacheline_aligned; u8 rx_buf[2]; @@ -203,7 +209,6 @@ static irqreturn_t adc0832_trigger_handl struct iio_poll_func *pf = p; struct iio_dev *indio_dev = pf->indio_dev; struct adc0832 *adc = iio_priv(indio_dev); - u8 data[24] = { }; /* 16x 1 byte ADC data + 8 bytes timestamp */ int scan_index; int i = 0;
@@ -221,10 +226,10 @@ static irqreturn_t adc0832_trigger_handl goto out; }
- data[i] = ret; + adc->data[i] = ret; i++; } - iio_push_to_buffers_with_timestamp(indio_dev, data, + iio_push_to_buffers_with_timestamp(indio_dev, adc->data, iio_get_time_ns(indio_dev)); out: mutex_unlock(&adc->lock);