iio:magnetometer:ak8974: Fix alignment and data leak issues
authorJonathan Cameron <Jonathan.Cameron@huawei.com>
Sun, 7 Jun 2020 15:53:49 +0000 (16:53 +0100)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Wed, 22 Jul 2020 07:34:02 +0000 (09:34 +0200)
commit496f933df1165a0ed826c345e295c977eb7fc7b4
tree0aa430118e76ac077ff9fbd72fafac65e5e8e853
parent569d24a1247a78ffbb15b0a0d9173b03ff4c5c0e
iio:magnetometer:ak8974: Fix alignment and data leak issues

commit 838e00b13bfd4cac8b24df25bfc58e2eb99bcc70 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() data.

This data is allocated with kzalloc so no data can leak appart from
previous readings.

Fixes: 7c94a8b2ee8cf ("iio: magn: add a driver for AK8974")
Reported-by: Lars-Peter Clausen <lars@metafoo.de>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: <Stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
drivers/iio/magnetometer/ak8974.c