patch "iio: mma8452: Fix trigger reference couting" added to char-misc-linus

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    iio: mma8452: Fix trigger reference couting

to my char-misc git tree which can be found at
    git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc.git
in the char-misc-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 cd0082235783f814241a1c9483fb89e405f4f892 Mon Sep 17 00:00:00 2001
From: Lars-Peter Clausen <lars@metafoo.de>
Date: Sun, 24 Oct 2021 11:26:59 +0200
Subject: iio: mma8452: Fix trigger reference couting

The mma8452 driver directly assigns a trigger to the struct iio_dev. The
IIO core when done using this trigger will call `iio_trigger_put()` to drop
the reference count by 1.

Without the matching `iio_trigger_get()` in the driver the reference count
can reach 0 too early, the trigger gets freed while still in use and a
use-after-free occurs.

Fix this by getting a reference to the trigger before assigning it to the
IIO device.

Fixes: ae6d9ce05691 ("iio: mma8452: Add support for interrupt driven triggers.")
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Link: https://lore.kernel.org/r/20211024092700.6844-1-lars@metafoo.de
Cc: <Stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
---
 drivers/iio/accel/mma8452.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/iio/accel/mma8452.c b/drivers/iio/accel/mma8452.c
index 715b8138fb71..09c7f10fefb6 100644
--- a/drivers/iio/accel/mma8452.c
+++ b/drivers/iio/accel/mma8452.c
@@ -1470,7 +1470,7 @@ static int mma8452_trigger_setup(struct iio_dev *indio_dev)
 	if (ret)
 		return ret;
 
-	indio_dev->trig = trig;
+	indio_dev->trig = iio_trigger_get(trig);
 
 	return 0;
 }
-- 
2.34.1