From 71a326dcd2a8eaf18af6e960af15ea0edcb1857c Mon Sep 17 00:00:00 2001 From: Jonathan Cameron Date: Sun, 20 Sep 2020 12:27:36 +0100 Subject: [PATCH] iio:light:st_uvis25: Fix timestamp alignment and prevent data leak. commit d837a996f57c29a985177bc03b0e599082047f27 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() This data is allocated with kzalloc() so no data can leak apart from previous readings. A local unsigned int variable is used for the regmap call so it is clear there is no potential issue with writing into the padding of the structure. Fixes: 3025c8688c1e ("iio: light: add support for UVIS25 sensor") Reported-by: Lars-Peter Clausen Signed-off-by: Jonathan Cameron Reviewed-by: Alexandru Ardelean Acked-by: Lorenzo Bianconi Cc: Link: https://lore.kernel.org/r/20200920112742.170751-3-jic23@kernel.org Signed-off-by: Greg Kroah-Hartman --- drivers/iio/light/st_uvis25.h | 5 +++++ drivers/iio/light/st_uvis25_core.c | 8 +++++--- 2 files changed, 10 insertions(+), 3 deletions(-) diff --git a/drivers/iio/light/st_uvis25.h b/drivers/iio/light/st_uvis25.h index 78bc56aad129..283086887caf 100644 --- a/drivers/iio/light/st_uvis25.h +++ b/drivers/iio/light/st_uvis25.h @@ -27,6 +27,11 @@ struct st_uvis25_hw { struct iio_trigger *trig; bool enabled; int irq; + /* Ensure timestamp is naturally aligned */ + struct { + u8 chan; + s64 ts __aligned(8); + } scan; }; extern const struct dev_pm_ops st_uvis25_pm_ops; diff --git a/drivers/iio/light/st_uvis25_core.c b/drivers/iio/light/st_uvis25_core.c index d262c254b895..9aaff35f49b0 100644 --- a/drivers/iio/light/st_uvis25_core.c +++ b/drivers/iio/light/st_uvis25_core.c @@ -234,17 +234,19 @@ static const struct iio_buffer_setup_ops st_uvis25_buffer_ops = { static irqreturn_t st_uvis25_buffer_handler_thread(int irq, void *p) { - u8 buffer[ALIGN(sizeof(u8), sizeof(s64)) + sizeof(s64)]; struct iio_poll_func *pf = p; struct iio_dev *iio_dev = pf->indio_dev; struct st_uvis25_hw *hw = iio_priv(iio_dev); + unsigned int val; int err; - err = regmap_read(hw->regmap, ST_UVIS25_REG_OUT_ADDR, (int *)buffer); + err = regmap_read(hw->regmap, ST_UVIS25_REG_OUT_ADDR, &val); if (err < 0) goto out; - iio_push_to_buffers_with_timestamp(iio_dev, buffer, + hw->scan.chan = val; + + iio_push_to_buffers_with_timestamp(iio_dev, &hw->scan, iio_get_time_ns(iio_dev)); out: