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From: amirmizi6@gmail.com
To: Eyal.Cohen@nuvoton.com, jarkko@kernel.org,
	oshrialkoby85@gmail.com, alexander.steffen@infineon.com,
	robh+dt@kernel.org, mark.rutland@arm.com, peterhuewe@gmx.de,
	jgg@ziepe.ca, arnd@arndb.de, gregkh@linuxfoundation.org,
	benoit.houyere@st.com, eajames@linux.ibm.com, joel@jms.id.au
Cc: devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-integrity@vger.kernel.org, oshri.alkoby@nuvoton.com,
	tmaimon77@gmail.com, gcwilson@us.ibm.com, kgoldman@us.ibm.com,
	Dan.Morav@nuvoton.com, oren.tanami@nuvoton.com,
	shmulik.hager@nuvoton.com, amir.mizinski@nuvoton.com,
	Amir Mizinski <amirmizi6@gmail.com>
Subject: [PATCH v15 4/6] tpm: tpm_tis: verify TPM_STS register is valid after locality request
Date: Tue, 14 Sep 2021 18:10:30 +0300	[thread overview]
Message-ID: <20210914151032.216122-5-amirmizi6@gmail.com> (raw)
In-Reply-To: <20210914151032.216122-1-amirmizi6@gmail.com>

From: Amir Mizinski <amirmizi6@gmail.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@st.com>
Signed-off-by: Amir Mizinski <amirmizi6@gmail.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 7ea7f64..f340a44 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


  parent reply	other threads:[~2021-09-14 15:13 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-14 15:10 [PATCH v15 0/6] Add tpm i2c ptp driver amirmizi6
2021-09-14 15:10 ` [PATCH v15 1/6] tpm_tis: Fix expected bit handling and send all bytes in one shot without last byte in exception amirmizi6
2021-09-14 16:58   ` Jarkko Sakkinen
2021-10-13  8:49     ` Amir Mizinski
2021-09-14 15:10 ` [PATCH v15 2/6] tpm: tpm_tis: Rewrite "tpm_tis_req_canceled()" amirmizi6
2021-09-14 15:10 ` [PATCH v15 3/6] tpm: Handle an exception for TPM Firmware Update mode amirmizi6
2021-09-14 15:10 ` amirmizi6 [this message]
2021-09-14 15:10 ` [PATCH v15 5/6] tpm: tpm_tis: add tpm_tis_i2c driver amirmizi6
2021-09-14 15:10 ` [PATCH v15 6/6] tpm: Add YAML schema for TPM TIS I2C options amirmizi6
2021-09-16 14:43   ` Rob Herring

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