From: Jonathan Cameron Jonathan.Cameron@huawei.com
commit 1e405bc2512f80a903ddd6ba8740cee885238d7f 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 with alignment explicitly requested. This data is allocated with kzalloc() so no data can leak apart from previous readings.
In this driver the timestamp can end up in various different locations depending on what other channels are enabled. As a result, we don't use a structure to specify it's position as that would be misleading.
Fixes: e717f8c6dfec ("iio: adc: Add the TI ads124s08 ADC code") 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 Cc: Dan Murphy dmurphy@ti.com Cc: Stable@vger.kernel.org Link: https://lore.kernel.org/r/20200920112742.170751-9-jic23@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/iio/adc/ti-ads124s08.c | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-)
--- a/drivers/iio/adc/ti-ads124s08.c +++ b/drivers/iio/adc/ti-ads124s08.c @@ -97,6 +97,14 @@ struct ads124s_private { struct gpio_desc *reset_gpio; struct spi_device *spi; struct mutex lock; + /* + * Used to correctly align data. + * Ensure timestamp is naturally aligned. + * Note that the full buffer length may not be needed if not + * all channels are enabled, as long as the alignment of the + * timestamp is maintained. + */ + u32 buffer[ADS124S08_MAX_CHANNELS + sizeof(s64)/sizeof(u32)] __aligned(8); u8 data[5] ____cacheline_aligned; };
@@ -270,7 +278,6 @@ static irqreturn_t ads124s_trigger_handl struct iio_poll_func *pf = p; struct iio_dev *indio_dev = pf->indio_dev; struct ads124s_private *priv = iio_priv(indio_dev); - u32 buffer[ADS124S08_MAX_CHANNELS + sizeof(s64)/sizeof(u32)]; int scan_index, j = 0; int ret;
@@ -285,7 +292,7 @@ static irqreturn_t ads124s_trigger_handl if (ret) dev_err(&priv->spi->dev, "Start ADC conversions failed\n");
- buffer[j] = ads124s_read(indio_dev, scan_index); + priv->buffer[j] = ads124s_read(indio_dev, scan_index); ret = ads124s_write_cmd(indio_dev, ADS124S08_STOP_CONV); if (ret) dev_err(&priv->spi->dev, "Stop ADC conversions failed\n"); @@ -293,7 +300,7 @@ static irqreturn_t ads124s_trigger_handl j++; }
- iio_push_to_buffers_with_timestamp(indio_dev, buffer, + iio_push_to_buffers_with_timestamp(indio_dev, priv->buffer, pf->timestamp);
iio_trigger_notify_done(indio_dev->trig);