Do not torn down the system when getting invalid status from a TPM chip. This can happen when panic-on-warn is used.
In addition, print out the value of TPM_STS.x instead of "invalid status". In order to get the earlier benefits for forensics, also call dump_stack().
Link: https://lore.kernel.org/keyrings/YKzlTR1AzUigShtZ@kroah.com/ Fixes: 55707d531af6 ("tpm_tis: Add a check for invalid status") Cc: stable@vger.kernel.org Cc: Hans de Goede hdegoede@redhat.com Cc: Greg KH greg@kroah.com Signed-off-by: Jarkko Sakkinen jarkko@kernel.org ---
v2: Dump also stack only once.
drivers/char/tpm/tpm_tis_core.c | 28 ++++++++++++++++++++-------- 1 file changed, 20 insertions(+), 8 deletions(-)
diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c index 55b9d3965ae1..ce410f19eff2 100644 --- a/drivers/char/tpm/tpm_tis_core.c +++ b/drivers/char/tpm/tpm_tis_core.c @@ -188,21 +188,33 @@ static int request_locality(struct tpm_chip *chip, int l) static u8 tpm_tis_status(struct tpm_chip *chip) { struct tpm_tis_data *priv = dev_get_drvdata(&chip->dev); - int rc; + static unsigned long klog_once; u8 status; + int rc;
rc = tpm_tis_read8(priv, TPM_STS(priv->locality), &status); if (rc < 0) return 0;
if (unlikely((status & TPM_STS_READ_ZERO) != 0)) { - /* - * If this trips, the chances are the read is - * returning 0xff because the locality hasn't been - * acquired. Usually because tpm_try_get_ops() hasn't - * been called before doing a TPM operation. - */ - WARN_ONCE(1, "TPM returned invalid status\n"); + if (!test_and_set_bit(BIT(0), &klog_once)) { + /* + * If this trips, the chances are the read is + * returning 0xff because the locality hasn't been + * acquired. Usually because tpm_try_get_ops() hasn't + * been called before doing a TPM operation. + */ + dev_err(&chip->dev, "invalid TPM_STS.x 0x%02x, dumping stack for forensics\n", + status); + + /* + * Dump stack for forensics, as invalid TPM_STS.x could be + * potentially triggered by impaired tpm_try_get_ops() or + * tpm_find_get_ops(). + */ + dump_stack(); + } + return 0; }