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uio: Fix use-after-free in uio_open 

commit 0c9ae0b860 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:
Guanghui Feng 2023-12-21 17:57:43 +08:00 committed by Greg Kroah-Hartman
parent 10cfdc51c3
commit 3174e0f7de
1 changed files with 3 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

7
drivers/uio/uio.c
View File

@ -464,13 +464,13 @@ static int uio_open(struct inode *inode, struct file *filep)
mutex_lock(&minor_lock);
idev = idr_find(&uio_idr, iminor(inode));
mutex_unlock(&minor_lock);
if (!idev) {
ret = -ENODEV;
mutex_unlock(&minor_lock);
goto out;
}
get_device(&idev->dev);
mutex_unlock(&minor_lock);
if (!try_module_get(idev->owner)) {
ret = -ENODEV;
@ -1019,9 +1019,8 @@ void uio_unregister_device(struct uio_info *info)
idev->info = NULL;
mutex_unlock(&idev->info_lock);
device_unregister(&idev->dev);
uio_free_minor(minor);
device_unregister(&idev->dev);
return;
}