[PATCH v2] driver: uio: fix possible memory leak and use-after-free in __uio_register_device

[liujian]

'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.

Also, in uio_dev_add_attributes() error handing case, idev is used after
device_unregister(), in which 'idev' has been released, touch idev cause
use-after-free.

Fixes: a93e7b331568 ("uio: Prevent device destruction while fds are open")
Fixes: e6789cd3dfb5 ("uio: Simplify uio error path by using devres
functions")
Signed-off-by: liujian <liujia...@huawei.com>
---
v1->v2:
change git log and fix code

 drivers/uio/uio.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/drivers/uio/uio.c b/drivers/uio/uio.c
index 1313422..be2a943 100644
--- a/drivers/uio/uio.c
+++ b/drivers/uio/uio.c
@@ -940,9 +940,12 @@ 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;
+       }
 
+       device_initialize(&idev->dev);
        idev->dev.devt = MKDEV(uio_major, idev->minor);
        idev->dev.class = &uio_class;
        idev->dev.parent = parent;
@@ -953,7 +956,7 @@ int __uio_register_device(struct module *owner,
        if (ret)
                goto err_device_create;
 
-       ret = device_register(&idev->dev);
+       ret = device_add(&idev->dev);
        if (ret)
                goto err_device_create;
 
@@ -985,9 +988,10 @@ int __uio_register_device(struct module *owner,
 err_request_irq:
        uio_dev_del_attributes(idev);
 err_uio_dev_add_attributes:
-       device_unregister(&idev->dev);
+       device_del(&idev->dev);
 err_device_create:
        uio_free_minor(idev);
+       put_device(&idev->dev);
        return ret;
 }
 EXPORT_SYMBOL_GPL(__uio_register_device);
-- 
2.7.4