linux-kernel - [PATCH 2/2] driver: uio: fix possible use-after-free in __uio_register

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Date:   Tue, 8 Jan 2019 21:01:48 +0800
From:   Liu Jian <liujian56@...wei.com>
To:     <gregkh@...uxfoundation.org>, <hamish.martin@...iedtelesis.co.nz>
CC:     <liujian56@...wei.com>, <linux-kernel@...r.kernel.org>
Subject: [PATCH 2/2] driver: uio: fix possible use-after-free in __uio_register_device

From: liujian <liujian56@...wei.com>

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@...wei.com>
Reviewed-by: Hamish Martin <hamish.martin@...iedtelesis.co.nz>
---
 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 7280552..be2a943 100644
--- a/drivers/uio/uio.c
+++ b/drivers/uio/uio.c
@@ -945,6 +945,7 @@ 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;
@@ -955,7 +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;
 
@@ -987,9 +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