This is a note to let you know that I've just added the patch titled
iio:proximity:mb1232: 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 f60e8bb84282b8e633956cfe74b4f0d64ca73cec Mon Sep 17 00:00:00 2001
From: Jonathan Cameron Jonathan.Cameron@huawei.com Date: Wed, 22 Jul 2020 16:50:42 +0100 Subject: iio:proximity:mb1232: 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 s16 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.
In this case the forced alignment of the ts is necessary to ensure correct padding on x86_32 where the s64 would only be 4 byte aligned.
Fixes: 16b05261537e ("mb1232.c: add distance iio sensor with i2c") Reported-by: Lars-Peter Clausen lars@metafoo.de Cc: Andreas Klinger ak@it-klinger.de Signed-off-by: Jonathan Cameron Jonathan.Cameron@huawei.com Cc: Stable@vger.kernel.org Reviewed-by: Andy Shevchenko andy.shevchenko@gmail.com --- drivers/iio/proximity/mb1232.c | 17 +++++++++-------- 1 file changed, 9 insertions(+), 8 deletions(-)
diff --git a/drivers/iio/proximity/mb1232.c b/drivers/iio/proximity/mb1232.c index 654564c45248..ad4b1fb2607a 100644 --- a/drivers/iio/proximity/mb1232.c +++ b/drivers/iio/proximity/mb1232.c @@ -40,6 +40,11 @@ struct mb1232_data { */ struct completion ranging; int irqnr; + /* Ensure correct alignment of data to push to IIO buffer */ + struct { + s16 distance; + s64 ts __aligned(8); + } scan; };
static irqreturn_t mb1232_handle_irq(int irq, void *dev_id) @@ -113,17 +118,13 @@ static irqreturn_t mb1232_trigger_handler(int irq, void *p) struct iio_poll_func *pf = p; struct iio_dev *indio_dev = pf->indio_dev; struct mb1232_data *data = iio_priv(indio_dev); - /* - * triggered buffer - * 16-bit channel + 48-bit padding + 64-bit timestamp - */ - s16 buffer[8] = { 0 };
- buffer[0] = mb1232_read_distance(data); - if (buffer[0] < 0) + data->scan.distance = mb1232_read_distance(data); + if (data->scan.distance < 0) goto err;
- iio_push_to_buffers_with_timestamp(indio_dev, buffer, pf->timestamp); + iio_push_to_buffers_with_timestamp(indio_dev, &data->scan, + pf->timestamp);
err: iio_trigger_notify_done(indio_dev->trig);