linux-kernel - [PATCH] iio: core: fix ioctl handlers removal

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Message-ID: <20210422201415.46378-1-tomasz.duszynski@octakon.com>
Date:   Thu, 22 Apr 2021 22:14:15 +0200
From:   Tomasz Duszynski <tomasz.duszynski@...akon.com>
To:     <linux-iio@...r.kernel.org>
CC:     <linux-kernel@...r.kernel.org>, <jic23@...nel.org>,
        <lars@...afoo.de>, Tomasz Duszynski <tomasz.duszynski@...akon.com>
Subject: [PATCH] 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.

Signed-off-by: Tomasz Duszynski <tomasz.duszynski@...akon.com>
---
 drivers/iio/industrialio-core.c | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/drivers/iio/industrialio-core.c b/drivers/iio/industrialio-core.c
index d92c58a94fe4..98944cfc7331 100644
--- a/drivers/iio/industrialio-core.c
+++ b/drivers/iio/industrialio-core.c
@@ -1939,9 +1939,6 @@ 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