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From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: stable@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	patches@lists.linux.dev,
	Chen Zhongjin <chenzhongjin@huawei.com>,
	Stable@vger.kernel.org,
	Jonathan Cameron <Jonathan.Cameron@huawei.com>
Subject: [PATCH 4.9 21/62] iio: core: Fix entry not deleted when iio_register_sw_trigger_type() fails
Date: Mon,  5 Dec 2022 20:09:18 +0100
Message-Id: <20221205190758.893528132@linuxfoundation.org>
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From: Chen Zhongjin <chenzhongjin@huawei.com>

commit 4ad09d956f8eacff61e67e5b13ba8ebec3232f76 upstream.

In iio_register_sw_trigger_type(), configfs_register_default_group() is
possible to fail, but the entry add to iio_trigger_types_list is not
deleted.

This leaves wild in iio_trigger_types_list, which can cause page fault
when module is loading again. So fix this by list_del(&t->list) in error
path.

BUG: unable to handle page fault for address: fffffbfff81d7400
Call Trace:
<TASK>
 iio_register_sw_trigger_type
 do_one_initcall
 do_init_module
 load_module
 ...

Fixes: b662f809d410 ("iio: core: Introduce IIO software triggers")
Signed-off-by: Chen Zhongjin <chenzhongjin@huawei.com>
Link: https://lore.kernel.org/r/20221108032802.168623-1-chenzhongjin@huawei.com
Cc: <Stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/iio/industrialio-sw-trigger.c |    6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

--- a/drivers/iio/industrialio-sw-trigger.c
+++ b/drivers/iio/industrialio-sw-trigger.c
@@ -61,8 +61,12 @@ int iio_register_sw_trigger_type(struct
 
 	t->group = configfs_register_default_group(iio_triggers_group, t->name,
 						&iio_trigger_type_group_type);
-	if (IS_ERR(t->group))
+	if (IS_ERR(t->group)) {
+		mutex_lock(&iio_trigger_types_lock);
+		list_del(&t->list);
+		mutex_unlock(&iio_trigger_types_lock);
 		ret = PTR_ERR(t->group);
+	}
 
 	return ret;
 }