linux-kernel - [PATCH] iio: core: Fix entry not deleted when iio_register_sw_trigger

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Date:   Tue, 8 Nov 2022 11:28:02 +0800
From:   Chen Zhongjin <chenzhongjin@...wei.com>
To:     <linux-kernel@...r.kernel.org>, <linux-iio@...r.kernel.org>
CC:     <jic23@...nel.org>, <lars@...afoo.de>, <daniel.baluta@...el.com>,
        <chenzhongjin@...wei.com>
Subject: [PATCH] iio: core: Fix entry not deleted when iio_register_sw_trigger_type() fails

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
RIP: 0010:__iio_find_sw_trigger_type.isra.3+0x62/0xb0 [industrialio_sw_trigger]
Call Trace:
<TASK>
 iio_register_sw_trigger_type+0x65/0x1f0 [industrialio_sw_trigger]
 do_one_initcall+0xd0/0x4e0
 do_init_module+0x1cf/0x6b0
 load_module+0x65c2/0x7820
 ...

Fixes: b662f809d410 ("iio: core: Introduce IIO software triggers")
Signed-off-by: Chen Zhongjin <chenzhongjin@...wei.com>
---
 drivers/iio/industrialio-sw-trigger.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/iio/industrialio-sw-trigger.c b/drivers/iio/industrialio-sw-trigger.c
index 994f03a71520..d86a3305d9e8 100644
--- a/drivers/iio/industrialio-sw-trigger.c
+++ b/drivers/iio/industrialio-sw-trigger.c
@@ -58,8 +58,12 @@ int iio_register_sw_trigger_type(struct iio_sw_trigger_type *t)

 	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;
 }
-- 
2.17.1