linux-kernel - [PATCH v7 3/7] tpm: tpm_tis: Rewrite "tpm_tis_req

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Message-Id: <20200427124931.115697-4-amirmizi6@gmail.com>
Date:   Mon, 27 Apr 2020 15:49:27 +0300
From:   amirmizi6@...il.com
To:     Eyal.Cohen@...oton.com, jarkko.sakkinen@...ux.intel.com,
        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 v7 3/7] tpm: tpm_tis: Rewrite "tpm_tis_req_canceled()"

From: Amir Mizinski <amirmizi6@...il.com>

Using this function while reading/writing data resulted in an aborted
operation.
After investigating the issue according to the TCG TPM Profile (PTP)
Specifications, I found that "request to cancel" should occur only if
TPM_STS.commandReady bit is lit.
Note that i couldn't find a case where the present condition
(in the linux kernel) is valid, so I'm removing the case for
"TPM_VID_WINBOND" since we have no need for it.

Also, the default comparison is wrong. Only cmdReady bit needs to be
compared instead of the full lower status register byte.

Fixes: 1f86605 (tpm: Fix cancellation of TPM commands (polling mode))
Signed-off-by: Amir Mizinski <amirmizi6@...il.com>
---
 drivers/char/tpm/tpm_tis_core.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c
index 5dd5604..682f950 100644
--- a/drivers/char/tpm/tpm_tis_core.c
+++ b/drivers/char/tpm/tpm_tis_core.c
@@ -715,13 +715,11 @@ static bool tpm_tis_req_canceled(struct tpm_chip *chip, u8 status)
 	struct tpm_tis_data *priv = dev_get_drvdata(&chip->dev);
 
 	switch (priv->manufacturer_id) {
-	case TPM_VID_WINBOND:
-		return ((status == TPM_STS_VALID) ||
-			(status == (TPM_STS_VALID | TPM_STS_COMMAND_READY)));
 	case TPM_VID_STM:
 		return (status == (TPM_STS_VALID | TPM_STS_COMMAND_READY));
 	default:
-		return (status == TPM_STS_COMMAND_READY);
+		return ((status & TPM_STS_COMMAND_READY) ==
+			TPM_STS_COMMAND_READY);
 	}
 }
 
-- 
2.7.4