patch "iio: core: fix ioctl handlers removal" added to staging-linus

[<gregkh@linuxfoundation.org>]

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

    iio: core: fix ioctl handlers removal

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 901f84de0e16bde10a72d7eb2f2eb73fcde8fa1a Mon Sep 17 00:00:00 2001
From: Tomasz Duszynski <tomasz.duszynski@octakon.com>
Date: Fri, 23 Apr 2021 10:02:44 +0200
Subject: iio: core: fix ioctl handlers removal

Currently ioctl handlers are removed twice. For the first time during
iio_device_unregister() then later on inside
iio_device_unregister_eventset() and iio_buffers_free_sysfs_and_mask().
Double free leads to kernel panic.

Fix this by not touching ioctl handlers list directly but rather
letting code responsible for registration call the matching cleanup
routine itself.

Fixes: 8dedcc3eee3ac ("iio: core: centralize ioctl() calls to the main chardev")
Signed-off-by: Tomasz Duszynski <tomasz.duszynski@octakon.com>
Acked-by: Alexandru Ardelean <ardeleanalex@gmail.com>
Cc: <Stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20210423080244.2790-1-tomasz.duszynski@octakon.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
---
 drivers/iio/industrialio-core.c | 6 ------
 1 file changed, 6 deletions(-)

diff --git a/drivers/iio/industrialio-core.c b/drivers/iio/industrialio-core.c
index d92c58a94fe4..9e59f5da3d28 100644
--- a/drivers/iio/industrialio-core.c
+++ b/drivers/iio/industrialio-core.c
@@ -1926,9 +1926,6 @@ EXPORT_SYMBOL(__iio_device_register);
  **/
 void iio_device_unregister(struct iio_dev *indio_dev)
 {
-	struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
-	struct iio_ioctl_handler *h, *t;
-
 	cdev_device_del(&indio_dev->chrdev, &indio_dev->dev);
 
 	mutex_lock(&indio_dev->info_exist_lock);
@@ -1939,9 +1936,6 @@ void iio_device_unregister(struct iio_dev *indio_dev)
 
 	indio_dev->info = NULL;
 
-	list_for_each_entry_safe(h, t, &iio_dev_opaque->ioctl_handlers, entry)
-		list_del(&h->entry);
-
 	iio_device_wakeup_eventset(indio_dev);
 	iio_buffer_wakeup_poll(indio_dev);
 
-- 
2.31.1