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

iio:light:max44000 Fix timestamp alignment and prevent data leak.

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 523628852a5f5f34a15252b2634d0498d3cfb347 Mon Sep 17 00:00:00 2001

From: Jonathan Cameron Jonathan.Cameron@huawei.com Date: Wed, 22 Jul 2020 16:50:45 +0100 Subject: iio:light:max44000 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(). This data is allocated with kzalloc so no data can leak appart from previous readings.

It is necessary to force the alignment of ts to avoid the padding on x86_32 being different from 64 bit platorms (it alows for 4 bytes aligned 8 byte types.

Fixes: 06ad7ea10e2b ("max44000: Initial triggered buffer support") Reported-by: Lars-Peter Clausen lars@metafoo.de Signed-off-by: Jonathan Cameron Jonathan.Cameron@huawei.com Reviewed-by: Andy Shevchenko andy.shevchenko@gmail.com Cc: Stable@vger.kernel.org --- drivers/iio/light/max44000.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/drivers/iio/light/max44000.c b/drivers/iio/light/max44000.c index aa8ed1e3e89a..b8e721bced5b 100644 --- a/drivers/iio/light/max44000.c +++ b/drivers/iio/light/max44000.c @@ -75,6 +75,11 @@ struct max44000_data { struct mutex lock; struct regmap *regmap; + /* Ensure naturally aligned timestamp */ + struct { + u16 channels[2]; + s64 ts __aligned(8); + } scan; };

/* Default scale is set to the minimum of 0.03125 or 1 / (1 << 5) lux */ @@ -488,7 +493,6 @@ static irqreturn_t max44000_trigger_handler(int irq, void *p) struct iio_poll_func *pf = p; struct iio_dev *indio_dev = pf->indio_dev; struct max44000_data *data = iio_priv(indio_dev); - u16 buf[8]; /* 2x u16 + padding + 8 bytes timestamp */ int index = 0; unsigned int regval; int ret; @@ -498,17 +502,17 @@ static irqreturn_t max44000_trigger_handler(int irq, void *p) ret = max44000_read_alsval(data); if (ret < 0) goto out_unlock; - buf[index++] = ret; + data->scan.channels[index++] = ret; } if (test_bit(MAX44000_SCAN_INDEX_PRX, indio_dev->active_scan_mask)) { ret = regmap_read(data->regmap, MAX44000_REG_PRX_DATA, &regval); if (ret < 0) goto out_unlock; - buf[index] = regval; + data->scan.channels[index] = regval; } mutex_unlock(&data->lock);

- iio_push_to_buffers_with_timestamp(indio_dev, buf, + iio_push_to_buffers_with_timestamp(indio_dev, &data->scan, iio_get_time_ns(indio_dev)); iio_trigger_notify_done(indio_dev->trig); return IRQ_HANDLED;