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

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Date:   Fri, 4 Jan 2019 22:19:08 +0800
From:   liujian <liujian56@...wei.com>
To:     <gregkh@...uxfoundation.org>
CC:     <liujian56@...wei.com>, <michal.simek@...inx.com>,
        <hamish.martin@...iedtelesis.co.nz>, <linux-kernel@...r.kernel.org>
Subject: [PATCH v2] driver: uio: fix possible memory leak and use-after-free in __uio_register_device

'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 <liujian56@...wei.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