[PATCH 6.1 0734/1146] chardev: fix error handling in cdev_device_add()

Greg Kroah-Hartman
2022-12-28T16:26:15Z

From: Yang Yingliang <yangyingliang@huawei.com>

[ Upstream commit 11fa7fefe3d8fac7da56bc9aa3dd5fb3081ca797 ]

While doing fault injection test, I got the following report:

------------[ cut here ]------------
kobject: '(null)' (0000000039956980): is not initialized, yet kobject_put() is being called.
WARNING: CPU: 3 PID: 6306 at kobject_put+0x23d/0x4e0
CPU: 3 PID: 6306 Comm: 283 Tainted: G W 6.1.0-rc2-00005-g307c1086d7c9 #1253
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1.1 04/01/2014
RIP: 0010:kobject_put+0x23d/0x4e0
Call Trace:
<TASK>
cdev_device_add+0x15e/0x1b0
__iio_device_register+0x13b4/0x1af0 [industrialio]
__devm_iio_device_register+0x22/0x90 [industrialio]
max517_probe+0x3d8/0x6b4 [max517]
i2c_device_probe+0xa81/0xc00

When device_add() is injected fault and returns error, if dev->devt is not set,
cdev_add() is not called, cdev_del() is not needed. Fix this by checking dev->devt
in error path.

Fixes: 233ed09d7fda ("chardev: add helper function to register char devs with a struct device")
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Link: https://lore.kernel.org/r/20221202030237.520280-1-yangyingliang@huawei.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/char_dev.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/char_dev.c b/fs/char_dev.c
index ba0ded7842a7..3f667292608c 100644
--- a/fs/char_dev.c
+++ b/fs/char_dev.c
@@ -547,7 +547,7 @@ int cdev_device_add(struct cdev *cdev, struct device *dev)
}

rc = device_add(dev);
- if (rc)
+ if (rc && dev->devt)
cdev_del(cdev);

return rc;
--
2.35.1