[PATCH AUTOSEL 5.17 23/60] extcon: Modify extcon device to be created after driver data is set

Sasha Levin
2022-06-07T19:09:10Z

From: bumwoo lee <bw365.lee@samsung.com>

[ Upstream commit 5dcc2afe716d69f5112ce035cb14f007461ff189 ]

Currently, someone can invoke the sysfs such as state_show()
intermittently before dev_set_drvdata() is done.
And it can be a cause of kernel Oops because of edev is Null at that time.
So modified the driver registration to after setting drviver data.

- Oops's backtrace.

Backtrace:
[<c067865c>] (state_show) from [<c05222e8>] (dev_attr_show)
[<c05222c0>] (dev_attr_show) from [<c02c66e0>] (sysfs_kf_seq_show)
[<c02c6648>] (sysfs_kf_seq_show) from [<c02c496c>] (kernfs_seq_show)
[<c02c4938>] (kernfs_seq_show) from [<c025e2a0>] (seq_read)
[<c025e11c>] (seq_read) from [<c02c50a0>] (kernfs_fop_read)
[<c02c5064>] (kernfs_fop_read) from [<c0231cac>] (__vfs_read)
[<c0231c5c>] (__vfs_read) from [<c0231ee0>] (vfs_read)
[<c0231e34>] (vfs_read) from [<c0232464>] (ksys_read)
[<c02323f0>] (ksys_read) from [<c02324fc>] (sys_read)
[<c02324e4>] (sys_read) from [<c00091d0>] (__sys_trace_return)

Signed-off-by: bumwoo lee <bw365.lee@samsung.com>
Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/extcon/extcon.c | 29 +++++++++++++++++------------
1 file changed, 17 insertions(+), 12 deletions(-)

diff --git a/drivers/extcon/extcon.c b/drivers/extcon/extcon.c
index adb957470c65..97e35c32bfa5 100644
--- a/drivers/extcon/extcon.c
+++ b/drivers/extcon/extcon.c
@@ -1220,19 +1220,14 @@ int extcon_dev_register(struct extcon_dev *edev)
edev->dev.type = &edev->extcon_dev_type;
}

- ret = device_register(&edev->dev);
- if (ret) {
- put_device(&edev->dev);
- goto err_dev;
- }
-
spin_lock_init(&edev->lock);
- edev->nh = devm_kcalloc(&edev->dev, edev->max_supported,
- sizeof(*edev->nh), GFP_KERNEL);
- if (!edev->nh) {
- ret = -ENOMEM;
- device_unregister(&edev->dev);
- goto err_dev;
+ if (edev->max_supported) {
+ edev->nh = kcalloc(edev->max_supported, sizeof(*edev->nh),
+ GFP_KERNEL);
+ if (!edev->nh) {
+ ret = -ENOMEM;
+ goto err_alloc_nh;
+ }
}

for (index = 0; index < edev->max_supported; index++)
@@ -1243,6 +1238,12 @@ int extcon_dev_register(struct extcon_dev *edev)
dev_set_drvdata(&edev->dev, edev);
edev->state = 0;

+ ret = device_register(&edev->dev);
+ if (ret) {
+ put_device(&edev->dev);
+ goto err_dev;
+ }
+
mutex_lock(&extcon_dev_list_lock);
list_add(&edev->entry, &extcon_dev_list);
mutex_unlock(&extcon_dev_list_lock);
@@ -1250,6 +1251,9 @@ int extcon_dev_register(struct extcon_dev *edev)
return 0;

err_dev:
+ if (edev->max_supported)
+ kfree(edev->nh);
+err_alloc_nh:
if (edev->max_supported)
kfree(edev->extcon_dev_type.groups);
err_alloc_groups:
@@ -1310,6 +1314,7 @@ void extcon_dev_unregister(struct extcon_dev *edev)
if (edev->max_supported) {
kfree(edev->extcon_dev_type.groups);
kfree(edev->cables);
+ kfree(edev->nh);
}

put_device(&edev->dev);
--
2.35.1