This is a note to let you know that I've just added the patch titled

iio:accel:bmc150-accel: Fix timestamp alignment and prevent data

to my staging git tree which can be found at git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging.git in the staging-linus branch.

The patch will show up in the next release of the linux-next tree (usually sometime within the next 24 hours during the week.)

The patch will hopefully also be merged in Linus's tree for the next -rc kernel release.

If you have any questions about this process, please let me know.

From a6f86f724394de3629da63fe5e1b7a4ab3396efe Mon Sep 17 00:00:00 2001

From: Jonathan Cameron Jonathan.Cameron@huawei.com Date: Wed, 22 Jul 2020 16:50:39 +0100 Subject: iio:accel:bmc150-accel: Fix timestamp alignment and prevent data leak.

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 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 ensured by use of an explicit c structure. This data is allocated with kzalloc so no data can leak appart from previous readings.

Fixes tag is beyond some major refactoring so likely manual backporting would be needed to get that far back.

Whilst the force alignment of the ts is not strictly necessary, it does make the code less fragile.

Fixes: 3bbec9773389 ("iio: bmc150_accel: add support for hardware fifo") Reported-by: Lars-Peter Clausen lars@metafoo.de Signed-off-by: Jonathan Cameron Jonathan.Cameron@huawei.com Acked-by: Srinivas Pandruvada srinivas.pandruvada@linux.intel.com Reviewed-by: Andy Shevchenko andy.shevchenko@gmail.com Cc: Stable@vger.kernel.org --- drivers/iio/accel/bmc150-accel-core.c | 15 ++++++++++++--- 1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/drivers/iio/accel/bmc150-accel-core.c b/drivers/iio/accel/bmc150-accel-core.c index 24864d9dfab5..48435865fdaf 100644 --- a/drivers/iio/accel/bmc150-accel-core.c +++ b/drivers/iio/accel/bmc150-accel-core.c @@ -189,6 +189,14 @@ struct bmc150_accel_data { struct mutex mutex; u8 fifo_mode, watermark; s16 buffer[8]; + /* + * Ensure there is sufficient space and correct alignment for + * the timestamp if enabled + */ + struct { + __le16 channels[3]; + s64 ts __aligned(8); + } scan; u8 bw_bits; u32 slope_dur; u32 slope_thres; @@ -922,15 +930,16 @@ static int __bmc150_accel_fifo_flush(struct iio_dev *indio_dev, * now. */ for (i = 0; i < count; i++) { - u16 sample[8]; int j, bit;

j = 0; for_each_set_bit(bit, indio_dev->active_scan_mask, indio_dev->masklength) - memcpy(&sample[j++], &buffer[i * 3 + bit], 2); + memcpy(&data->scan.channels[j++], &buffer[i * 3 + bit], + sizeof(data->scan.channels[0]));

- iio_push_to_buffers_with_timestamp(indio_dev, sample, tstamp); + iio_push_to_buffers_with_timestamp(indio_dev, &data->scan, + tstamp);

tstamp += sample_period; }