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17a8519cb3
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>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.