iio:humidity:hts221 Fix alignment and data leak issues
authorJonathan Cameron <Jonathan.Cameron@huawei.com>
Sun, 7 Jun 2020 15:53:53 +0000 (16:53 +0100)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Wed, 22 Jul 2020 07:34:03 +0000 (09:34 +0200)
commit953aedb099ad185d891bc42314a755ad558d9cde
tree78122bd69f0ae22a89a891b5136fc38389094881
parentc9a69ba9196a56453582a7b3681a99be6fd229c8
iio:humidity:hts221 Fix alignment and data leak issues

commit 5c49056ad9f3c786f7716da2dd47e4488fc6bd25 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
apart from previous readings.

Explicit alignment of ts needed to ensure consistent padding
on all architectures (particularly x86_32 with it's 4 byte alignment
of s64)

Fixes: e4a70e3e7d84 ("iio: humidity: add support to hts221 rh/temp combo device")
Reported-by: Lars-Peter Clausen <lars@metafoo.de>
Acked-by: Lorenzo Bianconi <lorenzo@kernel.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/humidity/hts221.h
drivers/iio/humidity/hts221_buffer.c