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uio: Fix use-after-free in uio_open
commit 0c9ae0b8605078eafc3bea053cc78791e97ba2e2 upstream.
core-1 core-2
-------------------------------------------------------
uio_unregister_device uio_open
idev = idr_find()
device_unregister(&idev->dev)
put_device(&idev->dev)
uio_device_release
get_device(&idev->dev)
kfree(idev)
uio_free_minor(minor)
uio_release
put_device(&idev->dev)
kfree(idev)
-------------------------------------------------------
In the core-1 uio_unregister_device(), the device_unregister will kfree
idev when the idev->dev kobject ref is 1. But after core-1
device_unregister, put_device and before doing kfree, the core-2 may
get_device. Then:
1. After core-1 kfree idev, the core-2 will do use-after-free for idev.
2. When core-2 do uio_release and put_device, the idev will be double
freed.
To address this issue, we can get idev atomic & inc idev reference with
minor_lock.
Fixes: 57c5f4df0a
("uio: fix crash after the device is unregistered")
Cc: stable <stable@kernel.org>
Signed-off-by: Guanghui Feng <guanghuifeng@linux.alibaba.com>
Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Link: https://lore.kernel.org/r/1703152663-59949-1-git-send-email-guanghuifeng@linux.alibaba.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
parent
f4d6dbaa43
commit
35f1026070
1 changed files with 3 additions and 4 deletions
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@ -466,13 +466,13 @@ static int uio_open(struct inode *inode, struct file *filep)
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mutex_lock(&minor_lock);
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idev = idr_find(&uio_idr, iminor(inode));
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mutex_unlock(&minor_lock);
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if (!idev) {
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ret = -ENODEV;
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mutex_unlock(&minor_lock);
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goto out;
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}
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get_device(&idev->dev);
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mutex_unlock(&minor_lock);
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if (!try_module_get(idev->owner)) {
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ret = -ENODEV;
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@ -1064,9 +1064,8 @@ void uio_unregister_device(struct uio_info *info)
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wake_up_interruptible(&idev->wait);
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kill_fasync(&idev->async_queue, SIGIO, POLL_HUP);
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device_unregister(&idev->dev);
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uio_free_minor(minor);
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device_unregister(&idev->dev);
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return;
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}
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