[PATCH AUTOSEL 4.14 072/371] driver: uio: fix possible use-after-free in __uio_register_device

Sasha Levin
2020-01-16T18:35:48Z

From: Liu Jian <liujian56@huawei.com>

[ Upstream commit 221a1f4ac12d2ab46246c160b2e00d1b1160d5d9 ]

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")
Signed-off-by: Liu Jian <liujian56@huawei.com>
Reviewed-by: Hamish Martin <hamish.martin@alliedtelesis.co.nz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/uio/uio.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/uio/uio.c b/drivers/uio/uio.c
index 4e9b0ff79b13..7c18536a3742 100644
--- a/drivers/uio/uio.c
+++ b/drivers/uio/uio.c
@@ -944,6 +944,7 @@ int __uio_register_device(struct module *owner,
return ret;
}

+ device_initialize(&idev->dev);
idev->dev.devt = MKDEV(uio_major, idev->minor);
idev->dev.class = &uio_class;
idev->dev.parent = parent;
@@ -954,7 +955,7 @@ 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;

@@ -986,9 +987,10 @@ 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);
--
2.20.1