On Mon, Dec 20, 2021 at 04:06:35PM +0100, Lino Sanfilippo wrote:
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.
Fixes: dcbeab1946454 ("tpm: fix crash in tpm_tis deinitialization") Cc: stable@vger.kernel.org Signed-off-by: Lino Sanfilippo LinoSanfilippo@gmx.de
Thank you.
Reviewed-by: Jarkko Sakkinen jarkko@kernel.org
BR, Jarkko