From: Lino Sanfilippo LinoSanfilippo@gmx.de
commit eabad7ba2c752392ae50f24a795093fb115b686d upstream.
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: 39d0099f9439 ("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 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/char/tpm/tpm-chip.c | 18 +++++++++++++----- 1 file changed, 13 insertions(+), 5 deletions(-)
--- a/drivers/char/tpm/tpm-chip.c +++ b/drivers/char/tpm/tpm-chip.c @@ -474,13 +474,21 @@ static void tpm_del_char_device(struct t
/* Make the driver uncallable. */ down_write(&chip->ops_sem); - if (chip->flags & TPM_CHIP_FLAG_TPM2) { - if (!tpm_chip_start(chip)) { - tpm2_shutdown(chip, TPM2_SU_CLEAR); - tpm_chip_stop(chip); + + /* + * Check if chip->ops is still valid: In case that the controller + * drivers shutdown handler unregisters the controller in its + * shutdown handler we are called twice and chip->ops to NULL. + */ + if (chip->ops) { + if (chip->flags & TPM_CHIP_FLAG_TPM2) { + if (!tpm_chip_start(chip)) { + tpm2_shutdown(chip, TPM2_SU_CLEAR); + tpm_chip_stop(chip); + } } + chip->ops = NULL; } - chip->ops = NULL; up_write(&chip->ops_sem); }