driver: uio: fix possible memory leak in __uio_register_device

mainline inclusion
from mainline-5.x
commit: 1a392b3d
category: bugfix
bugzilla: NA
CVE: NA

---------------------------

'idev' is malloced in __uio_register_device() and leak free it before
leaving from the uio_get_minor() error handing case, it will cause
memory leak.

Fixes: a93e7b33 ("uio: Prevent device destruction while fds are open")
Signed-off-by: NLiu Jian <liujian56@huawei.com>
Reviewed-by: NHamish Martin <hamish.martin@alliedtelesis.co.nz>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>
Reviewed-by: NLiu Jian <liujian56@huawei.com>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>

drivers/uio/uio.c

@@ -938,8 +938,10 @@ int __uio_register_device(struct module *owner,
 	atomic_set(&idev->event, 0);
 
 	ret = uio_get_minor(idev);
-	if (ret)
+	if (ret) {
+		kfree(idev);
 		return ret;
+	}
 
 	idev->dev.devt = MKDEV(uio_major, idev->minor);
 	idev->dev.class = &uio_class;