This is a note to let you know that I've just added the patch titled
iio:adc:ina2xx Fix timestamp alignment issue.
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 f8cd222feb82ecd82dcf610fcc15186f55f9c2b5 Mon Sep 17 00:00:00 2001
From: Jonathan Cameron Jonathan.Cameron@huawei.com Date: Wed, 22 Jul 2020 16:51:02 +0100 Subject: iio:adc:ina2xx Fix timestamp alignment issue. MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit
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 32 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 explicitly requested. This data is allocated with kzalloc so no data can leak apart from previous readings. The explicit alignment isn't technically needed here, but it reduced fragility and avoids cut and paste into drivers where it will be needed.
If we want this in older stables will need manual backport due to driver reworks.
Fixes: c43a102e67db ("iio: ina2xx: add support for TI INA2xx Power Monitors") Reported-by: Lars-Peter Clausen lars@metafoo.de Cc: Stefan Brüns stefan.bruens@rwth-aachen.de Cc: Marc Titinger mtitinger@baylibre.com Signed-off-by: Jonathan Cameron Jonathan.Cameron@huawei.com Reviewed-by: Andy Shevchenko andy.shevchenko@gmail.com Cc: Stable@vger.kernel.org --- drivers/iio/adc/ina2xx-adc.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-)
diff --git a/drivers/iio/adc/ina2xx-adc.c b/drivers/iio/adc/ina2xx-adc.c index 5ed63e874292..b573ec60a8b8 100644 --- a/drivers/iio/adc/ina2xx-adc.c +++ b/drivers/iio/adc/ina2xx-adc.c @@ -146,6 +146,11 @@ struct ina2xx_chip_info { int range_vbus; /* Bus voltage maximum in V */ int pga_gain_vshunt; /* Shunt voltage PGA gain */ bool allow_async_readout; + /* data buffer needs space for channel data and timestamp */ + struct { + u16 chan[4]; + u64 ts __aligned(8); + } scan; };
static const struct ina2xx_config ina2xx_config[] = { @@ -738,8 +743,6 @@ static int ina2xx_conversion_ready(struct iio_dev *indio_dev) static int ina2xx_work_buffer(struct iio_dev *indio_dev) { struct ina2xx_chip_info *chip = iio_priv(indio_dev); - /* data buffer needs space for channel data and timestap */ - unsigned short data[4 + sizeof(s64)/sizeof(short)]; int bit, ret, i = 0; s64 time;
@@ -758,10 +761,10 @@ static int ina2xx_work_buffer(struct iio_dev *indio_dev) if (ret < 0) return ret;
- data[i++] = val; + chip->scan.chan[i++] = val; }
- iio_push_to_buffers_with_timestamp(indio_dev, data, time); + iio_push_to_buffers_with_timestamp(indio_dev, &chip->scan, time);
return 0; };