diff options
author | Lino Sanfilippo <LinoSanfilippo@gmx.de> | 2021-12-20 16:06:35 +0100 |
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committer | Jarkko Sakkinen <jarkko@kernel.org> | 2022-01-09 00:18:49 +0200 |
commit | eabad7ba2c752392ae50f24a795093fb115b686d (patch) | |
tree | 157c9916bd0eacb2323e68e50564357e0222e41b | |
parent | 0aa698787aa2a9e8840987e54ba2982559de6404 (diff) | |
download | linux-eabad7ba2c752392ae50f24a795093fb115b686d.tar.bz2 |
tpm: fix potential NULL pointer access in tpm_del_char_device
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>
-rw-r--r-- | drivers/char/tpm/tpm-chip.c | 18 |
1 files changed, 13 insertions, 5 deletions
diff --git a/drivers/char/tpm/tpm-chip.c b/drivers/char/tpm/tpm-chip.c index b4ed3ae67a4b..b009e7479b70 100644 --- 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 tpm_chip *chip) /* 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); } |