4.9-stable review patch. If anyone has any objections, please let me know.
------------------ From: Alexander Steffen <[email protected]> commit 302a6ad7fc77146191126a1f3e2c5d724fd72416 upstream. TIS v1.3 for TPM 1.2 and PTP for TPM 2.0 disagree about which timeout value applies to reading a valid burstcount. It is TIMEOUT_D according to TIS, but TIMEOUT_A according to PTP, so choose the appropriate value depending on whether we deal with a TPM 1.2 or a TPM 2.0. This is important since according to the PTP TIMEOUT_D is much smaller than TIMEOUT_A. So the previous implementation could run into timeouts with a TPM 2.0, even though the TPM was behaving perfectly fine. During tpm2_probe TIMEOUT_D will be used even with a TPM 2.0, because TPM_CHIP_FLAG_TPM2 is not yet set. This is fine, since the timeout values will only be changed afterwards by tpm_get_timeouts. Until then TIS_TIMEOUT_D_MAX applies, which is large enough. Fixes: aec04cbdf723 ("tpm: TPM 2.0 FIFO Interface") Signed-off-by: Alexander Steffen <[email protected]> Signed-off-by: Peter Huewe <[email protected]> Reviewed-by: Jarkko Sakkinen <[email protected]> Signed-off-by: Jarkko Sakkinen <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- drivers/char/tpm/tpm_tis_core.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) --- a/drivers/char/tpm/tpm_tis_core.c +++ b/drivers/char/tpm/tpm_tis_core.c @@ -160,8 +160,10 @@ static int get_burstcount(struct tpm_chi u32 value; /* wait for burstcount */ - /* which timeout value, spec has 2 answers (c & d) */ - stop = jiffies + chip->timeout_d; + if (chip->flags & TPM_CHIP_FLAG_TPM2) + stop = jiffies + chip->timeout_a; + else + stop = jiffies + chip->timeout_d; do { rc = tpm_tis_read32(priv, TPM_STS(priv->locality), &value); if (rc < 0)
