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Message-Id: <20211024164855.250362-5-amirmizi6@gmail.com> Date: Sun, 24 Oct 2021 19:48:53 +0300 From: amirmizi6@...il.com To: Eyal.Cohen@...oton.com, jarkko@...nel.org, oshrialkoby85@...il.com, alexander.steffen@...ineon.com, robh+dt@...nel.org, mark.rutland@....com, peterhuewe@....de, jgg@...pe.ca, arnd@...db.de, gregkh@...uxfoundation.org, benoit.houyere@...com, eajames@...ux.ibm.com, joel@....id.au Cc: devicetree@...r.kernel.org, linux-kernel@...r.kernel.org, linux-integrity@...r.kernel.org, oshri.alkoby@...oton.com, tmaimon77@...il.com, gcwilson@...ibm.com, kgoldman@...ibm.com, Dan.Morav@...oton.com, oren.tanami@...oton.com, shmulik.hager@...oton.com, amir.mizinski@...oton.com, Amir Mizinski <amirmizi6@...il.com> Subject: [PATCH v17 4/6] tpm: tpm_tis: Verify TPM_STS register is valid after locality request From: Amir Mizinski <amirmizi6@...il.com> This issue could occur when the TPM does not update TPM_STS register after a locality request (TPM_STS Initial value = 0xFF) and a TPM_STS register read occurs in the tpm_tis_status(chip) function call. When a call to tpm_tis_send_data() function is made after a request_locality() call, the condition ("if ((status & TPM_STS_COMMAND_READY) == 0)") is checked. At this moment if the status value is 0xFF, then it is considered, wrongly, in “ready” state (by checking only one bit). However, at this moment the TPM is, in fact, in "Idle" state and remains in "Idle" state because "tpm_tis_ready(chip);" was not executed. Waiting for the condition TPM_STS.tpmGo == 0, will ensure that the TPM status register has the correct value. Suggested-by: Benoit Houyere <benoit.houyere@...com> Signed-off-by: Amir Mizinski <amirmizi6@...il.com> --- drivers/char/tpm/tpm_tis_core.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c index e1c4a5a..237b952 100644 --- a/drivers/char/tpm/tpm_tis_core.c +++ b/drivers/char/tpm/tpm_tis_core.c @@ -177,8 +177,14 @@ static int request_locality(struct tpm_chip *chip, int l) } else { /* wait for burstcount */ do { - if (check_locality(chip, l)) + if (check_locality(chip, l)) { + if (wait_for_tpm_stat(chip, TPM_STS_GO, 0, + chip->timeout_c, + &priv->int_queue, + false) < 0) + return -ETIME; return l; + } tpm_msleep(TPM_TIMEOUT); } while (time_before(jiffies, stop)); } -- 2.7.4
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