linux-kernel - [PATCH] tpm: tpm_try_transmit() refactor error flow.

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Message-Id: <20181016133716.17842-1-tomas.winkler@intel.com>
Date:   Tue, 16 Oct 2018 16:37:16 +0300
From:   Tomas Winkler <tomas.winkler@...el.com>
To:     Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>,
        Jason Gunthorpe <jgg@...pe.ca>
Cc:     Nayna Jain <nayna@...ux.vnet.ibm.com>,
        Alexander Usyskin <alexander.usyskin@...el.com>,
        Tadeusz Struk <tadeusz.struk@...el.com>,
        linux-integrity@...r.kernel.org,
        linux-security-module@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Tomas Winkler <tomas.winkler@...el.com>, stable@...r.kernel.org
Subject: [PATCH] tpm: tpm_try_transmit() refactor error flow.

First, rename out_no_locality to out_locality for bailing out on
both tpm_cmd_ready() and tpm_request_locality() failure.
Second, ignore the return value of go_to_idle() as  it may override
the return value of the actual tpm operation, the go_to_idle() error
will be caught on any consequent command.
Last, fix the wrong 'goto out', that jumped back instead of forward.

Cc: stable@...r.kernel.org
Fixes: 627448e85c76 ("tpm: separate cmd_ready/go_idle from runtime_pm")
Signed-off-by: Tomas Winkler <tomas.winkler@...el.com>
---
 drivers/char/tpm/tpm-interface.c | 15 ++++++++-------
 1 file changed, 8 insertions(+), 7 deletions(-)

diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c
index 129f640424b7..95db630dd722 100644
--- a/drivers/char/tpm/tpm-interface.c
+++ b/drivers/char/tpm/tpm-interface.c
@@ -477,13 +477,15 @@ static ssize_t tpm_try_transmit(struct tpm_chip *chip,
 
 	if (need_locality) {
 		rc = tpm_request_locality(chip, flags);
-		if (rc < 0)
-			goto out_no_locality;
+		if (rc < 0) {
+			need_locality = false;
+			goto out_locality;
+		}
 	}
 
 	rc = tpm_cmd_ready(chip, flags);
 	if (rc)
-		goto out;
+		goto out_locality;
 
 	rc = tpm2_prepare_space(chip, space, ordinal, buf);
 	if (rc)
@@ -547,14 +549,13 @@ static ssize_t tpm_try_transmit(struct tpm_chip *chip,
 		dev_err(&chip->dev, "tpm2_commit_space: error %d\n", rc);
 
 out:
-	rc = tpm_go_idle(chip, flags);
-	if (rc)
-		goto out;
+	/* may fail but do not override previous error value in rc */
+	tpm_go_idle(chip, flags);
 
+out_locality:
 	if (need_locality)
 		tpm_relinquish_locality(chip, flags);
 
-out_no_locality:
 	if (chip->ops->clk_enable != NULL)
 		chip->ops->clk_enable(chip, false);
 
-- 
2.14.4