| Message ID | 20200722155103.979802-22-jic23@kernel.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | IIO: Fused set 1 and 2 of timestamp alignment fixes | expand |
On Wed, 22 Jul 2020 16:50:57 +0100 Jonathan Cameron <jic23@kernel.org> wrote: > From: Jonathan Cameron <Jonathan.Cameron@huawei.com> > > 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 <lars@metafoo.de> > Cc: Mårten Lindahl <martenli@axis.com> > Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com> Applied and marked for stable. thanks, Jonathan > --- > 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);
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);