linux-kernel - [PATCH 4.14 079/343] driver: uio: fix possible use-after-free in __uio_register

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Message-Id: <20200124092930.296466829@linuxfoundation.org>
Date:   Fri, 24 Jan 2020 10:28:17 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Liu Jian <liujian56@...wei.com>,
        Hamish Martin <hamish.martin@...iedtelesis.co.nz>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 4.14 079/343] driver: uio: fix possible use-after-free in __uio_register_device

From: Liu Jian <liujian56@...wei.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@...wei.com>
Reviewed-by: Hamish Martin <hamish.martin@...iedtelesis.co.nz>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Signed-off-by: Sasha Levin <sashal@...nel.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 4e9b0ff79b131..7c18536a3742a 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