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c592fafbdb
The thermal child device reuses the parent MFD-device device-tree node
when registering a thermal zone, but did not take a reference to the
node.
This leads to a reference imbalance, and potential use-after-free, when
the node reference is dropped by the platform-bus device destructor
(once for the child and later again for the parent).
Fix this by dropping any reference already held to a device-tree node
and getting a reference to the parent's node which will be balanced on
reprobe or on platform-device release, whichever comes first.
Note that simply clearing the of_node pointer on probe errors and on
driver unbind would not allow the use of device-managed resources as
specifically thermal_zone_of_sensor_unregister() claims that a valid
device-tree node pointer is needed during deregistration (even if it
currently does not seem to use it).
Fixes: ec4664b3fd ("thermal: max77620: Add thermal driver for reporting junction temp")
Cc: stable <stable@vger.kernel.org> # 4.9
Cc: Laxman Dewangan <ldewangan@nvidia.com>
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. 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.