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eabad7ba2c
Some SPI controller drivers unregister the controller in the shutdown
handler (e.g. BCM2835). If such a controller is used with a TPM 2 slave
chip->ops may be accessed when it is already NULL:
At system shutdown the pre-shutdown handler tpm_class_shutdown() shuts down
TPM 2 and sets chip->ops to NULL. Then at SPI controller unregistration
tpm_tis_spi_remove() is called and eventually calls tpm_del_char_device()
which tries to shut down TPM 2 again. Thereby it accesses chip->ops again:
(tpm_del_char_device calls tpm_chip_start which calls tpm_clk_enable which
calls chip->ops->clk_enable).
Avoid the NULL pointer access by testing if chip->ops is valid and skipping
the TPM 2 shutdown procedure in case it is NULL.
Cc: stable@vger.kernel.org
Signed-off-by: Lino Sanfilippo <LinoSanfilippo@gmx.de>
Fixes: 39d0099f94 ("powerpc/pseries: Add shutdown() to vio_driver and vio_bus")
Reviewed-by: Stefan Berger <stefanb@linux.ibm.com>
Tested-by: Stefan Berger <stefanb@linux.ibm.com>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.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
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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.