[24/25] iio:adc:ina2xx Fix timestamp alignment issue.
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Message ID 20200525170628.503283-25-jic23@kernel.org
State New
Headers show
Series
  • IIO: 2nd set of timestamp alignment fixes.
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Commit Message

Jonathan Cameron May 25, 2020, 5:06 p.m. UTC
From: Jonathan Cameron <Jonathan.Cameron@huawei.com>

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.

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>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Stefan BrĂ¼ns <stefan.bruens@rwth-aachen.de>
Cc: Marc Titinger <mtitinger@baylibre.com>
---
 drivers/iio/adc/ina2xx-adc.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

Patch
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diff --git a/drivers/iio/adc/ina2xx-adc.c b/drivers/iio/adc/ina2xx-adc.c
index bdd7cba6f6b0..ed2d069b791a 100644
--- a/drivers/iio/adc/ina2xx-adc.c
+++ b/drivers/iio/adc/ina2xx-adc.c
@@ -146,6 +146,8 @@  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 timestap */
+	unsigned short data[4 + sizeof(s64)/sizeof(short)] __aligned(8);
 };
 
 static const struct ina2xx_config ina2xx_config[] = {
@@ -738,8 +740,6 @@  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 +758,10 @@  static int ina2xx_work_buffer(struct iio_dev *indio_dev)
 		if (ret < 0)
 			return ret;
 
-		data[i++] = val;
+		chip->data[i++] = val;
 	}
 
-	iio_push_to_buffers_with_timestamp(indio_dev, data, time);
+	iio_push_to_buffers_with_timestamp(indio_dev, chip->data, time);
 
 	return 0;
 };