Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
From:   amirmizi6@gmail.com
To:     Eyal.Cohen@nuvoton.com, jarkko.sakkinen@linux.intel.com,
        oshrialkoby85@gmail.com, alexander.steffen@infineon.com,
        robh+dt@kernel.org,
        "benoit.houyere@st.com--to=mark.rutland"@arm.com,
        peterhuewe@gmx.de, christophe-h.richard@st.com, jgg@ziepe.ca,
        arnd@arndb.de, gregkh@linuxfoundation.org
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>,
        Benoit Houyere <benoit.houyere@st.com>
Subject: [PATCH v11 6/8] tpm: tpm_tis: verify TPM_STS register is valid after locality request
Date:   Thu, 18 Jun 2020 16:43:41 +0300
Message-Id: <20200618134344.243537-7-amirmizi6@gmail.com>
In-Reply-To: <20200618134344.243537-1-amirmizi6@gmail.com>
References: <20200618134344.243537-1-amirmizi6@gmail.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

From: Amir Mizinski <amirmizi6@gmail.com>

Issue could result 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 (tpm_tis_status(chip)).

Checking the next condition("if ((status & TPM_STS_COMMAND_READY) == 0)"),
the status will be at 0xFF and will be 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.

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 2636ec7..fd485d2 100644
--- a/drivers/char/tpm/tpm_tis_core.c
+++ b/drivers/char/tpm/tpm_tis_core.c
@@ -221,8 +221,14 @@ 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