[PATCH 3.16 165/305] iio: proximity: as3935: fix buffer stack trashing

[Ben Hutchings]

3.16.37-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Matt Ranostay <mranostay@xxxxxxxxx>

commit 37b1ba2c68cfbe37f5f45bb91bcfaf2b016ae6a1 upstream.

Buffer wasn't of a valid size to allow the timestamp, and correct padding.
This patchset also moves the buffer off the stack, and onto the heap.

Cc: george.mccollister@xxxxxxxxx
Signed-off-by: Matt Ranostay <mranostay@xxxxxxxxx>
Signed-off-by: Jonathan Cameron <jic23@xxxxxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
 drivers/iio/proximity/as3935.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

--- a/drivers/iio/proximity/as3935.c
+++ b/drivers/iio/proximity/as3935.c
@@ -64,6 +64,7 @@ struct as3935_state {
 	struct delayed_work work;
 
 	u32 tune_cap;
+	u8 buffer[16]; /* 8-bit data + 56-bit padding + 64-bit timestamp */
 	u8 buf[2] ____cacheline_aligned;
 };
 
@@ -212,9 +213,10 @@ static irqreturn_t as3935_trigger_handle
 	ret = as3935_read(st, AS3935_DATA, &val);
 	if (ret)
 		goto err_read;
-	val &= AS3935_DATA_MASK;
 
-	iio_push_to_buffers_with_timestamp(indio_dev, &val, pf->timestamp);
+	st->buffer[0] = val & AS3935_DATA_MASK;
+	iio_push_to_buffers_with_timestamp(indio_dev, &st->buffer,
+					   pf->timestamp);
 err_read:
 	iio_trigger_notify_done(indio_dev->trig);