| Message ID | 20200722155103.979802-3-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 16:50:38 +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 a 16 byte u8 array 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 > ensured by use of an explicit c structure. This data is allocated > with kzalloc so no data can leak appart from previous readings. > > The additional forcing of the 8 byte alignment of the timestamp > is not strictly necessary but makes the code less fragile by > making this explicit. > > Fixes: c7eeea93ac60 ("iio: Add Freescale MMA8452Q 3-axis accelerometer driver") > Reported-by: Lars-Peter Clausen <lars@metafoo.de> > Cc: Peter Meerwald <pmeerw@pmeerw.net> > Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com> Applied to the fixes-togreg branch of iio.git. Thanks, Jonathan > --- > drivers/iio/accel/mma8452.c | 11 ++++++++--- > 1 file changed, 8 insertions(+), 3 deletions(-) > > diff --git a/drivers/iio/accel/mma8452.c b/drivers/iio/accel/mma8452.c > index ba27f8673131..1cf2b5db26ca 100644 > --- a/drivers/iio/accel/mma8452.c > +++ b/drivers/iio/accel/mma8452.c > @@ -110,6 +110,12 @@ struct mma8452_data { > int sleep_val; > struct regulator *vdd_reg; > struct regulator *vddio_reg; > + > + /* Ensure correct alignment of time stamp when present */ > + struct { > + __be16 channels[3]; > + s64 ts __aligned(8); > + } buffer; > }; > > /** > @@ -1091,14 +1097,13 @@ static irqreturn_t mma8452_trigger_handler(int irq, void *p) > struct iio_poll_func *pf = p; > struct iio_dev *indio_dev = pf->indio_dev; > struct mma8452_data *data = iio_priv(indio_dev); > - u8 buffer[16]; /* 3 16-bit channels + padding + ts */ > int ret; > > - ret = mma8452_read(data, (__be16 *)buffer); > + ret = mma8452_read(data, data->buffer.channels); > if (ret < 0) > goto done; > > - iio_push_to_buffers_with_timestamp(indio_dev, buffer, > + iio_push_to_buffers_with_timestamp(indio_dev, &data->buffer, > iio_get_time_ns(indio_dev)); > > done:
diff --git a/drivers/iio/accel/mma8452.c b/drivers/iio/accel/mma8452.c index ba27f8673131..1cf2b5db26ca 100644 --- a/drivers/iio/accel/mma8452.c +++ b/drivers/iio/accel/mma8452.c @@ -110,6 +110,12 @@ struct mma8452_data { int sleep_val; struct regulator *vdd_reg; struct regulator *vddio_reg; + + /* Ensure correct alignment of time stamp when present */ + struct { + __be16 channels[3]; + s64 ts __aligned(8); + } buffer; }; /** @@ -1091,14 +1097,13 @@ static irqreturn_t mma8452_trigger_handler(int irq, void *p) struct iio_poll_func *pf = p; struct iio_dev *indio_dev = pf->indio_dev; struct mma8452_data *data = iio_priv(indio_dev); - u8 buffer[16]; /* 3 16-bit channels + padding + ts */ int ret; - ret = mma8452_read(data, (__be16 *)buffer); + ret = mma8452_read(data, data->buffer.channels); if (ret < 0) goto done; - iio_push_to_buffers_with_timestamp(indio_dev, buffer, + iio_push_to_buffers_with_timestamp(indio_dev, &data->buffer, iio_get_time_ns(indio_dev)); done: