linux-kernel - [PATCH v6 03/17] tpm: return 0 from pcrs_show() when tpm1_pcr

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Message-Id: <20181113122609.21643-4-jarkko.sakkinen@linux.intel.com>
Date:   Tue, 13 Nov 2018 14:25:52 +0200
From:   Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
To:     linux-integrity@...r.kernel.org
Cc:     linux-security-module@...r.kernel.org,
        James Bottomley <James.Bottomley@...senPartnership.com>,
        Tomas Winkler <tomas.winkler@...el.com>,
        Tadeusz Struk <tadeusz.struk@...el.com>,
        Stefan Berger <stefanb@...ux.vnet.ibm.com>,
        Nayna Jain <nayna@...ux.ibm.com>,
        Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>,
        Peter Huewe <peterhuewe@....de>,
        Jason Gunthorpe <jgg@...pe.ca>, Arnd Bergmann <arnd@...db.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-kernel@...r.kernel.org (open list)
Subject: [PATCH v6 03/17] tpm: return 0 from pcrs_show() when tpm1_pcr_read() fails

Do not print partial list of PCRs when tpm1_pcr_read() fails but instead
return 0 from pcrs_show(). This is consistent behavior with other sysfs
functions.

Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
Reviewed-by: Stefan Berger <stefanb@...ux.ibm.com>
---
 drivers/char/tpm/tpm-sysfs.c | 13 ++++++-------
 1 file changed, 6 insertions(+), 7 deletions(-)

diff --git a/drivers/char/tpm/tpm-sysfs.c b/drivers/char/tpm/tpm-sysfs.c
index 7ed7eb6f906a..928d4e839bb7 100644
--- a/drivers/char/tpm/tpm-sysfs.c
+++ b/drivers/char/tpm/tpm-sysfs.c
@@ -100,22 +100,21 @@ static ssize_t pcrs_show(struct device *dev, struct device_attribute *attr,
 {
 	cap_t cap;
 	u8 digest[TPM_DIGEST_SIZE];
-	ssize_t rc;
 	u32 i, j, num_pcrs;
 	char *str = buf;
 	struct tpm_chip *chip = to_tpm_chip(dev);
 
-	rc = tpm1_getcap(chip, TPM_CAP_PROP_PCR, &cap,
-			 "attempting to determine the number of PCRS",
-			 sizeof(cap.num_pcrs));
-	if (rc)
+	if (tpm1_getcap(chip, TPM_CAP_PROP_PCR, &cap,
+			"attempting to determine the number of PCRS",
+			sizeof(cap.num_pcrs)))
 		return 0;
 
 	num_pcrs = be32_to_cpu(cap.num_pcrs);
 	for (i = 0; i < num_pcrs; i++) {
-		rc = tpm1_pcr_read(chip, i, digest);
-		if (rc)
+		if (tpm1_pcr_read(chip, i, digest)) {
+			str = buf;
 			break;
+		}
 		str += sprintf(str, "PCR-%02d: ", i);
 		for (j = 0; j < TPM_DIGEST_SIZE; j++)
 			str += sprintf(str, "%02X ", digest[j]);
-- 
2.19.1