linux-kernel - [PATCH v10 4/4] tpm_vpm_proxy: Use stack for TPM_CC_SET

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Message-Id: <20250921020804.1088824-5-jarkko@kernel.org>
Date: Sun, 21 Sep 2025 05:08:04 +0300
From: Jarkko Sakkinen <jarkko@...nel.org>
To: linux-integrity@...r.kernel.org
Cc: Stefano Garzarella <sgarzare@...hat.com>,
	Jarkko Sakkinen <jarkko.sakkinen@...nsys.com>,
	Peter Huewe <peterhuewe@....de>,
	Jarkko Sakkinen <jarkko@...nel.org>,
	Jason Gunthorpe <jgg@...pe.ca>,
	David Howells <dhowells@...hat.com>,
	Paul Moore <paul@...l-moore.com>,
	James Morris <jmorris@...ei.org>,
	"Serge E. Hallyn" <serge@...lyn.com>,
	linux-kernel@...r.kernel.org (open list),
	keyrings@...r.kernel.org (open list:KEYS/KEYRINGS),
	linux-security-module@...r.kernel.org (open list:SECURITY SUBSYSTEM)
Subject: [PATCH v10 4/4] tpm_vpm_proxy: Use stack for TPM_CC_SET_LOCALITY

From: Jarkko Sakkinen <jarkko.sakkinen@...nsys.com>

Use stack allocation for TPM_CC_SET_LOCALITY, as it has known fixed size.

Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@...nsys.com>
---
 drivers/char/tpm/tpm1-cmd.c       |  2 +-
 drivers/char/tpm/tpm_vtpm_proxy.c | 12 +++++-------
 2 files changed, 6 insertions(+), 8 deletions(-)

diff --git a/drivers/char/tpm/tpm1-cmd.c b/drivers/char/tpm/tpm1-cmd.c
index 11c16ad9b2a7..433908cfb4a9 100644
--- a/drivers/char/tpm/tpm1-cmd.c
+++ b/drivers/char/tpm/tpm1-cmd.c
@@ -328,7 +328,7 @@ static int tpm1_startup(struct tpm_chip *chip)
 	int rc;
 
 	dev_info(&chip->dev, "TPM_Startup\n");
-	tpm_buf_init(buf, TPM_BUF_INT_SIZE);
+	tpm_buf_init(buf, TPM_BUF_MIN_SIZE);
 	tpm_buf_reset(buf, TPM_TAG_RQU_COMMAND, TPM_ORD_STARTUP);
 	tpm_buf_append_u16(buf, TPM_ST_CLEAR);
 	rc = tpm_transmit_cmd(chip, buf, 0, "TPM_Startup");
diff --git a/drivers/char/tpm/tpm_vtpm_proxy.c b/drivers/char/tpm/tpm_vtpm_proxy.c
index e5de14379eb2..0f1b1b67ed4e 100644
--- a/drivers/char/tpm/tpm_vtpm_proxy.c
+++ b/drivers/char/tpm/tpm_vtpm_proxy.c
@@ -395,15 +395,13 @@ static bool vtpm_proxy_tpm_req_canceled(struct tpm_chip  *chip, u8 status)
 
 static int vtpm_proxy_request_locality(struct tpm_chip *chip, int locality)
 {
-	int rc;
-	const struct tpm_header *header;
 	struct proxy_dev *proxy_dev = dev_get_drvdata(&chip->dev);
+	u8 buf_data[TPM_BUF_MIN_SIZE];
+	struct tpm_buf *buf = (struct tpm_buf *)buf_data;
+	const struct tpm_header *header;
+	int rc;
 
-	struct tpm_buf *buf __free(kfree) = kzalloc(PAGE_SIZE, GFP_KERNEL);
-	if (!buf)
-		return -ENOMEM;
-
-	tpm_buf_init(buf, TPM_BUF_MAX_SIZE);
+	tpm_buf_init(buf, TPM_BUF_MIN_SIZE);
 	if (chip->flags & TPM_CHIP_FLAG_TPM2)
 		tpm_buf_reset(buf, TPM2_ST_SESSIONS, TPM2_CC_SET_LOCALITY);
 	else
-- 
2.39.5