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Message-Id: <20250919111139.2472612-1-jarkko@kernel.org>
Date: Fri, 19 Sep 2025 14:11:37 +0300
From: Jarkko Sakkinen <jarkko@...nel.org>
To: linux-integrity@...r.kernel.org
Cc: Stefan Berger <stefanb@...ux.ibm.com>,
	Jarkko Sakkinen <jarkko.sakkinen@...nsys.com>,
	Peter Huewe <peterhuewe@....de>,
	Jarkko Sakkinen <jarkko@...nel.org>,
	Jason Gunthorpe <jgg@...pe.ca>,
	James Bottomley <James.Bottomley@...senPartnership.com>,
	Mimi Zohar <zohar@...ux.ibm.com>,
	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-TRUSTED),
	linux-security-module@...r.kernel.org (open list:SECURITY SUBSYSTEM)
Subject: [PATCH v6] tpm: Make TPM buffer allocations more robust

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

Drop 'tpm_buf_init', 'tpm_buf_init_sized' and 'tpm_buf_free'. Refine
'struct tpm_buf' to hold capacity in order to enable stack allocation and
sizes other than page size.

The updated 'struct tpm_buf' can be allocated either from stack or heap.

The contract is the following:

1. 'tpm_buf_reset' and 'tpm_buf_reset_size' expect that on the first run
   the passed buffer is zeroed by the caller (e.g. via memset or kzalloc).
2. The same buffer can be reused. On the second and subsequent resets the
   aforementioned functions verify that 'buf_size' has the same value, and
   emits warning if not.

As a consequence 'struct tpm_buf' instance can be easily wrapped into
managed allocation:

	struct tpm_buf *buf __free(kfree) buf = kzalloc(PAGE_SIZE,
							GFP_KERNEL);

Reviewed-by: Stefan Berger <stefanb@...ux.ibm.com>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@...nsys.com>
---
v6:
- Removed two empty lines as requested by Stefan:
  https://lore.kernel.org/linux-integrity/be1c5bef-7c97-4173-b417-986dc90d779c@linux.ibm.com/
- Add 'capacity' field as this makes easy to stretch tpm_buf into stack
  allocation.
v5:
- I tested this version also with TPM 1.2 by booting up and checking
  that sysfs attributes work.
- Fixed the length check against capacity (James) with TPM_BUF_CAPACITY.
- Fixed declaration style: do it at the site (Jason).
- Improved commit message (Stefan).
- Removed "out" label from tpm2_pcr_read() (Stefan).
- Removed spurious "return rc;" from tpm2_get_pcr_allocation() (Stefan).
v4:
- Wrote a more a descriptive short summary and improved description.
- Fixed the error in documentation: there is 4090 bytes of space left
  for the payload - not 4088 bytes.
- Turned tpm_buf_alloc() into inline function.
v3:
- Removed the cleanup class and moved on using __free(kfree) instead.
- Removed `buf_size` (James).
- I'm open for the idea of splitting still (Jason) but I'll hold
  at least this revision just to check that my core idea here
  is correct.
v2:
- Implement also memory allocation using the cleanup class.
- Rewrote the commit message.
- Implemented CLASS_TPM_BUF() helper macro.
---
 drivers/char/tpm/tpm-buf.c                |  57 +----
 drivers/char/tpm/tpm-sysfs.c              |  19 +-
 drivers/char/tpm/tpm1-cmd.c               | 143 ++++++------
 drivers/char/tpm/tpm2-cmd.c               | 270 ++++++++++------------
 drivers/char/tpm/tpm2-sessions.c          | 118 +++++-----
 drivers/char/tpm/tpm2-space.c             |  42 ++--
 drivers/char/tpm/tpm_vtpm_proxy.c         |  29 +--
 include/linux/tpm.h                       |  17 +-
 security/keys/trusted-keys/trusted_tpm1.c |  40 ++--
 security/keys/trusted-keys/trusted_tpm2.c | 153 ++++++------
 10 files changed, 379 insertions(+), 509 deletions(-)

diff --git a/drivers/char/tpm/tpm-buf.c b/drivers/char/tpm/tpm-buf.c
index dc882fc9fa9e..1fe9bc99305c 100644
--- a/drivers/char/tpm/tpm-buf.c
+++ b/drivers/char/tpm/tpm-buf.c
@@ -7,32 +7,14 @@
 #include <linux/module.h>
 #include <linux/tpm.h>
 
-/**
- * tpm_buf_init() - Allocate and initialize a TPM command
- * @buf:	A &tpm_buf
- * @tag:	TPM_TAG_RQU_COMMAND, TPM2_ST_NO_SESSIONS or TPM2_ST_SESSIONS
- * @ordinal:	A command ordinal
- *
- * Return: 0 or -ENOMEM
- */
-int tpm_buf_init(struct tpm_buf *buf, u16 tag, u32 ordinal)
-{
-	buf->data = (u8 *)__get_free_page(GFP_KERNEL);
-	if (!buf->data)
-		return -ENOMEM;
-
-	tpm_buf_reset(buf, tag, ordinal);
-	return 0;
-}
-EXPORT_SYMBOL_GPL(tpm_buf_init);
-
 /**
  * tpm_buf_reset() - Initialize a TPM command
  * @buf:	A &tpm_buf
+ * @buf_size:	Size of the buffer.
  * @tag:	TPM_TAG_RQU_COMMAND, TPM2_ST_NO_SESSIONS or TPM2_ST_SESSIONS
  * @ordinal:	A command ordinal
  */
-void tpm_buf_reset(struct tpm_buf *buf, u16 tag, u32 ordinal)
+void tpm_buf_reset(struct tpm_buf *buf, u16 buf_size, u16 tag, u32 ordinal)
 {
 	struct tpm_header *head = (struct tpm_header *)buf->data;
 
@@ -41,49 +23,30 @@ void tpm_buf_reset(struct tpm_buf *buf, u16 tag, u32 ordinal)
 
 	buf->flags = 0;
 	buf->length = sizeof(*head);
+	buf->capacity = buf_size - sizeof(*buf);
+	buf->handles = 0;
 	head->tag = cpu_to_be16(tag);
 	head->length = cpu_to_be32(sizeof(*head));
 	head->ordinal = cpu_to_be32(ordinal);
-	buf->handles = 0;
 }
 EXPORT_SYMBOL_GPL(tpm_buf_reset);
 
-/**
- * tpm_buf_init_sized() - Allocate and initialize a sized (TPM2B) buffer
- * @buf:	A @tpm_buf
- *
- * Return: 0 or -ENOMEM
- */
-int tpm_buf_init_sized(struct tpm_buf *buf)
-{
-	buf->data = (u8 *)__get_free_page(GFP_KERNEL);
-	if (!buf->data)
-		return -ENOMEM;
-
-	tpm_buf_reset_sized(buf);
-	return 0;
-}
-EXPORT_SYMBOL_GPL(tpm_buf_init_sized);
-
 /**
  * tpm_buf_reset_sized() - Initialize a sized buffer
  * @buf:	A &tpm_buf
+ * @buf_size:	Size of the buffer.
  */
-void tpm_buf_reset_sized(struct tpm_buf *buf)
+void tpm_buf_reset_sized(struct tpm_buf *buf, u16 buf_size)
 {
 	buf->flags = TPM_BUF_TPM2B;
 	buf->length = 2;
+	buf->capacity = buf_size - sizeof(*buf);
+	buf->handles = 0;
 	buf->data[0] = 0;
 	buf->data[1] = 0;
 }
 EXPORT_SYMBOL_GPL(tpm_buf_reset_sized);
 
-void tpm_buf_destroy(struct tpm_buf *buf)
-{
-	free_page((unsigned long)buf->data);
-}
-EXPORT_SYMBOL_GPL(tpm_buf_destroy);
-
 /**
  * tpm_buf_length() - Return the number of bytes consumed by the data
  * @buf:	A &tpm_buf
@@ -108,7 +71,7 @@ void tpm_buf_append(struct tpm_buf *buf, const u8 *new_data, u16 new_length)
 	if (buf->flags & TPM_BUF_OVERFLOW)
 		return;
 
-	if ((buf->length + new_length) > PAGE_SIZE) {
+	if ((buf->length + new_length) > buf->capacity) {
 		WARN(1, "tpm_buf: write overflow\n");
 		buf->flags |= TPM_BUF_OVERFLOW;
 		return;
@@ -242,5 +205,3 @@ u32 tpm_buf_read_u32(struct tpm_buf *buf, off_t *offset)
 	return be32_to_cpu(value);
 }
 EXPORT_SYMBOL_GPL(tpm_buf_read_u32);
-
-
diff --git a/drivers/char/tpm/tpm-sysfs.c b/drivers/char/tpm/tpm-sysfs.c
index 94231f052ea7..68328ca6367d 100644
--- a/drivers/char/tpm/tpm-sysfs.c
+++ b/drivers/char/tpm/tpm-sysfs.c
@@ -32,28 +32,29 @@ struct tpm_readpubek_out {
 static ssize_t pubek_show(struct device *dev, struct device_attribute *attr,
 			  char *buf)
 {
-	struct tpm_buf tpm_buf;
 	struct tpm_readpubek_out *out;
 	int i;
 	char *str = buf;
 	struct tpm_chip *chip = to_tpm_chip(dev);
 	char anti_replay[20];
 
+	struct tpm_buf *tpm_buf __free(kfree) = kzalloc(PAGE_SIZE, GFP_KERNEL);
+	if (!tpm_buf)
+		return -ENOMEM;
+
 	memset(&anti_replay, 0, sizeof(anti_replay));
 
 	if (tpm_try_get_ops(chip))
 		return 0;
 
-	if (tpm_buf_init(&tpm_buf, TPM_TAG_RQU_COMMAND, TPM_ORD_READPUBEK))
-		goto out_ops;
-
-	tpm_buf_append(&tpm_buf, anti_replay, sizeof(anti_replay));
+	tpm_buf_reset(tpm_buf, PAGE_SIZE, TPM_TAG_RQU_COMMAND, TPM_ORD_READPUBEK);
+	tpm_buf_append(tpm_buf, anti_replay, sizeof(anti_replay));
 
-	if (tpm_transmit_cmd(chip, &tpm_buf, READ_PUBEK_RESULT_MIN_BODY_SIZE,
+	if (tpm_transmit_cmd(chip, tpm_buf, READ_PUBEK_RESULT_MIN_BODY_SIZE,
 			     "attempting to read the PUBEK"))
-		goto out_buf;
+		goto out_ops;
 
-	out = (struct tpm_readpubek_out *)&tpm_buf.data[10];
+	out = (struct tpm_readpubek_out *)&tpm_buf->data[10];
 	str +=
 	    sprintf(str,
 		    "Algorithm: %4ph\n"
@@ -71,8 +72,6 @@ static ssize_t pubek_show(struct device *dev, struct device_attribute *attr,
 	for (i = 0; i < 256; i += 16)
 		str += sprintf(str, "%16ph\n", &out->modulus[i]);
 
-out_buf:
-	tpm_buf_destroy(&tpm_buf);
 out_ops:
 	tpm_put_ops(chip);
 	return str - buf;
diff --git a/drivers/char/tpm/tpm1-cmd.c b/drivers/char/tpm/tpm1-cmd.c
index cf64c7385105..e7dc01c68a92 100644
--- a/drivers/char/tpm/tpm1-cmd.c
+++ b/drivers/char/tpm/tpm1-cmd.c
@@ -323,19 +323,18 @@ unsigned long tpm1_calc_ordinal_duration(struct tpm_chip *chip, u32 ordinal)
  */
 static int tpm1_startup(struct tpm_chip *chip)
 {
-	struct tpm_buf buf;
 	int rc;
 
-	dev_info(&chip->dev, "starting up the TPM manually\n");
+	struct tpm_buf *buf __free(kfree) = kzalloc(PAGE_SIZE, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
 
-	rc = tpm_buf_init(&buf, TPM_TAG_RQU_COMMAND, TPM_ORD_STARTUP);
-	if (rc < 0)
-		return rc;
+	dev_info(&chip->dev, "starting up the TPM manually\n");
 
-	tpm_buf_append_u16(&buf, TPM_ST_CLEAR);
+	tpm_buf_reset(buf, PAGE_SIZE, TPM_TAG_RQU_COMMAND, TPM_ORD_STARTUP);
+	tpm_buf_append_u16(buf, TPM_ST_CLEAR);
 
-	rc = tpm_transmit_cmd(chip, &buf, 0, "attempting to start the TPM");
-	tpm_buf_destroy(&buf);
+	rc = tpm_transmit_cmd(chip, buf, 0, "attempting to start the TPM");
 	return rc;
 }
 
@@ -463,18 +462,17 @@ int tpm1_get_timeouts(struct tpm_chip *chip)
 int tpm1_pcr_extend(struct tpm_chip *chip, u32 pcr_idx, const u8 *hash,
 		    const char *log_msg)
 {
-	struct tpm_buf buf;
 	int rc;
 
-	rc = tpm_buf_init(&buf, TPM_TAG_RQU_COMMAND, TPM_ORD_PCR_EXTEND);
-	if (rc)
-		return rc;
+	struct tpm_buf *buf __free(kfree) = kzalloc(PAGE_SIZE, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
 
-	tpm_buf_append_u32(&buf, pcr_idx);
-	tpm_buf_append(&buf, hash, TPM_DIGEST_SIZE);
+	tpm_buf_reset(buf, PAGE_SIZE, TPM_TAG_RQU_COMMAND, TPM_ORD_PCR_EXTEND);
+	tpm_buf_append_u32(buf, pcr_idx);
+	tpm_buf_append(buf, hash, TPM_DIGEST_SIZE);
 
-	rc = tpm_transmit_cmd(chip, &buf, TPM_DIGEST_SIZE, log_msg);
-	tpm_buf_destroy(&buf);
+	rc = tpm_transmit_cmd(chip, buf, TPM_DIGEST_SIZE, log_msg);
 	return rc;
 }
 
@@ -482,31 +480,31 @@ int tpm1_pcr_extend(struct tpm_chip *chip, u32 pcr_idx, const u8 *hash,
 ssize_t tpm1_getcap(struct tpm_chip *chip, u32 subcap_id, cap_t *cap,
 		    const char *desc, size_t min_cap_length)
 {
-	struct tpm_buf buf;
 	int rc;
 
-	rc = tpm_buf_init(&buf, TPM_TAG_RQU_COMMAND, TPM_ORD_GET_CAP);
-	if (rc)
-		return rc;
+	struct tpm_buf *buf __free(kfree) = kzalloc(PAGE_SIZE, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	tpm_buf_reset(buf, PAGE_SIZE, TPM_TAG_RQU_COMMAND, TPM_ORD_GET_CAP);
 
 	if (subcap_id == TPM_CAP_VERSION_1_1 ||
 	    subcap_id == TPM_CAP_VERSION_1_2) {
-		tpm_buf_append_u32(&buf, subcap_id);
-		tpm_buf_append_u32(&buf, 0);
+		tpm_buf_append_u32(buf, subcap_id);
+		tpm_buf_append_u32(buf, 0);
 	} else {
 		if (subcap_id == TPM_CAP_FLAG_PERM ||
 		    subcap_id == TPM_CAP_FLAG_VOL)
-			tpm_buf_append_u32(&buf, TPM_CAP_FLAG);
+			tpm_buf_append_u32(buf, TPM_CAP_FLAG);
 		else
-			tpm_buf_append_u32(&buf, TPM_CAP_PROP);
+			tpm_buf_append_u32(buf, TPM_CAP_PROP);
 
-		tpm_buf_append_u32(&buf, 4);
-		tpm_buf_append_u32(&buf, subcap_id);
+		tpm_buf_append_u32(buf, 4);
+		tpm_buf_append_u32(buf, subcap_id);
 	}
-	rc = tpm_transmit_cmd(chip, &buf, min_cap_length, desc);
+	rc = tpm_transmit_cmd(chip, buf, min_cap_length, desc);
 	if (!rc)
-		*cap = *(cap_t *)&buf.data[TPM_HEADER_SIZE + 4];
-	tpm_buf_destroy(&buf);
+		*cap = *(cap_t *)&buf->data[TPM_HEADER_SIZE + 4];
 	return rc;
 }
 EXPORT_SYMBOL_GPL(tpm1_getcap);
@@ -531,81 +529,72 @@ int tpm1_get_random(struct tpm_chip *chip, u8 *dest, size_t max)
 {
 	struct tpm1_get_random_out *out;
 	u32 num_bytes =  min_t(u32, max, TPM_MAX_RNG_DATA);
-	struct tpm_buf buf;
 	u32 total = 0;
 	int retries = 5;
 	u32 recd;
 	int rc;
 
-	rc = tpm_buf_init(&buf, TPM_TAG_RQU_COMMAND, TPM_ORD_GET_RANDOM);
-	if (rc)
-		return rc;
+	struct tpm_buf *buf __free(kfree) = kzalloc(PAGE_SIZE, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	tpm_buf_reset(buf, PAGE_SIZE, TPM_TAG_RQU_COMMAND, TPM_ORD_GET_RANDOM);
 
 	do {
-		tpm_buf_append_u32(&buf, num_bytes);
+		tpm_buf_append_u32(buf, num_bytes);
 
-		rc = tpm_transmit_cmd(chip, &buf, sizeof(out->rng_data_len),
+		rc = tpm_transmit_cmd(chip, buf, sizeof(out->rng_data_len),
 				      "attempting get random");
 		if (rc) {
 			if (rc > 0)
 				rc = -EIO;
-			goto out;
+			return rc;
 		}
 
-		out = (struct tpm1_get_random_out *)&buf.data[TPM_HEADER_SIZE];
+		out = (struct tpm1_get_random_out *)&buf->data[TPM_HEADER_SIZE];
 
 		recd = be32_to_cpu(out->rng_data_len);
-		if (recd > num_bytes) {
-			rc = -EFAULT;
-			goto out;
-		}
+		if (recd > num_bytes)
+			return -EFAULT;
+
+		if (buf->length < TPM_HEADER_SIZE +
+				  sizeof(out->rng_data_len) + recd)
+			return -EFAULT;
 
-		if (tpm_buf_length(&buf) < TPM_HEADER_SIZE +
-					   sizeof(out->rng_data_len) + recd) {
-			rc = -EFAULT;
-			goto out;
-		}
 		memcpy(dest, out->rng_data, recd);
 
 		dest += recd;
 		total += recd;
 		num_bytes -= recd;
 
-		tpm_buf_reset(&buf, TPM_TAG_RQU_COMMAND, TPM_ORD_GET_RANDOM);
+		tpm_buf_reset(buf, PAGE_SIZE, TPM_TAG_RQU_COMMAND, TPM_ORD_GET_RANDOM);
 	} while (retries-- && total < max);
 
 	rc = total ? (int)total : -EIO;
-out:
-	tpm_buf_destroy(&buf);
 	return rc;
 }
 
 #define TPM_ORD_PCRREAD 21
 int tpm1_pcr_read(struct tpm_chip *chip, u32 pcr_idx, u8 *res_buf)
 {
-	struct tpm_buf buf;
 	int rc;
 
-	rc = tpm_buf_init(&buf, TPM_TAG_RQU_COMMAND, TPM_ORD_PCRREAD);
-	if (rc)
-		return rc;
+	struct tpm_buf *buf __free(kfree) = kzalloc(PAGE_SIZE, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
 
-	tpm_buf_append_u32(&buf, pcr_idx);
+	tpm_buf_reset(buf, PAGE_SIZE, TPM_TAG_RQU_COMMAND, TPM_ORD_PCRREAD);
+	tpm_buf_append_u32(buf, pcr_idx);
 
-	rc = tpm_transmit_cmd(chip, &buf, TPM_DIGEST_SIZE,
+	rc = tpm_transmit_cmd(chip, buf, TPM_DIGEST_SIZE,
 			      "attempting to read a pcr value");
 	if (rc)
-		goto out;
-
-	if (tpm_buf_length(&buf) < TPM_DIGEST_SIZE) {
-		rc = -EFAULT;
-		goto out;
-	}
+		return rc;
 
-	memcpy(res_buf, &buf.data[TPM_HEADER_SIZE], TPM_DIGEST_SIZE);
+	if (buf->length < TPM_DIGEST_SIZE)
+		return -EFAULT;
 
-out:
-	tpm_buf_destroy(&buf);
+	memcpy(res_buf, &buf->data[TPM_HEADER_SIZE], TPM_DIGEST_SIZE);
 	return rc;
 }
 
@@ -619,15 +608,14 @@ int tpm1_pcr_read(struct tpm_chip *chip, u32 pcr_idx, u8 *res_buf)
  */
 static int tpm1_continue_selftest(struct tpm_chip *chip)
 {
-	struct tpm_buf buf;
 	int rc;
 
-	rc = tpm_buf_init(&buf, TPM_TAG_RQU_COMMAND, TPM_ORD_CONTINUE_SELFTEST);
-	if (rc)
-		return rc;
+	struct tpm_buf *buf __free(kfree) = kzalloc(PAGE_SIZE, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
 
-	rc = tpm_transmit_cmd(chip, &buf, 0, "continue selftest");
-	tpm_buf_destroy(&buf);
+	tpm_buf_reset(buf, PAGE_SIZE, TPM_TAG_RQU_COMMAND, TPM_ORD_CONTINUE_SELFTEST);
+	rc = tpm_transmit_cmd(chip, buf, 0, "continue selftest");
 	return rc;
 }
 
@@ -742,22 +730,23 @@ int tpm1_auto_startup(struct tpm_chip *chip)
 int tpm1_pm_suspend(struct tpm_chip *chip, u32 tpm_suspend_pcr)
 {
 	u8 dummy_hash[TPM_DIGEST_SIZE] = { 0 };
-	struct tpm_buf buf;
 	unsigned int try;
 	int rc;
 
+	struct tpm_buf *buf __free(kfree) = kzalloc(PAGE_SIZE, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
 
 	/* for buggy tpm, flush pcrs with extend to selected dummy */
 	if (tpm_suspend_pcr)
 		rc = tpm1_pcr_extend(chip, tpm_suspend_pcr, dummy_hash,
 				     "extending dummy pcr before suspend");
 
-	rc = tpm_buf_init(&buf, TPM_TAG_RQU_COMMAND, TPM_ORD_SAVESTATE);
-	if (rc)
-		return rc;
+	tpm_buf_reset(buf, PAGE_SIZE, TPM_TAG_RQU_COMMAND, TPM_ORD_SAVESTATE);
+
 	/* now do the actual savestate */
 	for (try = 0; try < TPM_RETRY; try++) {
-		rc = tpm_transmit_cmd(chip, &buf, 0, NULL);
+		rc = tpm_transmit_cmd(chip, buf, 0, NULL);
 		/*
 		 * If the TPM indicates that it is too busy to respond to
 		 * this command then retry before giving up.  It can take
@@ -772,7 +761,7 @@ int tpm1_pm_suspend(struct tpm_chip *chip, u32 tpm_suspend_pcr)
 			break;
 		tpm_msleep(TPM_TIMEOUT_RETRY);
 
-		tpm_buf_reset(&buf, TPM_TAG_RQU_COMMAND, TPM_ORD_SAVESTATE);
+		tpm_buf_reset(buf, PAGE_SIZE, TPM_TAG_RQU_COMMAND, TPM_ORD_SAVESTATE);
 	}
 
 	if (rc)
@@ -782,8 +771,6 @@ int tpm1_pm_suspend(struct tpm_chip *chip, u32 tpm_suspend_pcr)
 		dev_warn(&chip->dev, "TPM savestate took %dms\n",
 			 try * TPM_TIMEOUT_RETRY);
 
-	tpm_buf_destroy(&buf);
-
 	return rc;
 }
 
diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c
index 524d802ede26..56d8bc496cd6 100644
--- a/drivers/char/tpm/tpm2-cmd.c
+++ b/drivers/char/tpm/tpm2-cmd.c
@@ -167,12 +167,15 @@ int tpm2_pcr_read(struct tpm_chip *chip, u32 pcr_idx,
 {
 	int i;
 	int rc;
-	struct tpm_buf buf;
 	struct tpm2_pcr_read_out *out;
 	u8 pcr_select[TPM2_PCR_SELECT_MIN] = {0};
 	u16 digest_size;
 	u16 expected_digest_size = 0;
 
+	struct tpm_buf *buf __free(kfree) = kzalloc(PAGE_SIZE, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
 	if (pcr_idx >= TPM2_PLATFORM_PCR)
 		return -EINVAL;
 
@@ -187,36 +190,30 @@ int tpm2_pcr_read(struct tpm_chip *chip, u32 pcr_idx,
 		expected_digest_size = chip->allocated_banks[i].digest_size;
 	}
 
-	rc = tpm_buf_init(&buf, TPM2_ST_NO_SESSIONS, TPM2_CC_PCR_READ);
-	if (rc)
-		return rc;
+	tpm_buf_reset(buf, PAGE_SIZE, TPM2_ST_NO_SESSIONS, TPM2_CC_PCR_READ);
 
 	pcr_select[pcr_idx >> 3] = 1 << (pcr_idx & 0x7);
 
-	tpm_buf_append_u32(&buf, 1);
-	tpm_buf_append_u16(&buf, digest->alg_id);
-	tpm_buf_append_u8(&buf, TPM2_PCR_SELECT_MIN);
-	tpm_buf_append(&buf, (const unsigned char *)pcr_select,
+	tpm_buf_append_u32(buf, 1);
+	tpm_buf_append_u16(buf, digest->alg_id);
+	tpm_buf_append_u8(buf, TPM2_PCR_SELECT_MIN);
+	tpm_buf_append(buf, (const unsigned char *)pcr_select,
 		       sizeof(pcr_select));
 
-	rc = tpm_transmit_cmd(chip, &buf, 0, "attempting to read a pcr value");
+	rc = tpm_transmit_cmd(chip, buf, 0, "attempting to read a pcr value");
 	if (rc)
-		goto out;
+		return rc;
 
-	out = (struct tpm2_pcr_read_out *)&buf.data[TPM_HEADER_SIZE];
+	out = (struct tpm2_pcr_read_out *)&buf->data[TPM_HEADER_SIZE];
 	digest_size = be16_to_cpu(out->digest_size);
 	if (digest_size > sizeof(digest->digest) ||
-	    (!digest_size_ptr && digest_size != expected_digest_size)) {
-		rc = -EINVAL;
-		goto out;
-	}
+	    (!digest_size_ptr && digest_size != expected_digest_size))
+		return rc;
 
 	if (digest_size_ptr)
 		*digest_size_ptr = digest_size;
 
 	memcpy(digest->digest, out->digest, digest_size);
-out:
-	tpm_buf_destroy(&buf);
 	return rc;
 }
 
@@ -232,46 +229,42 @@ int tpm2_pcr_read(struct tpm_chip *chip, u32 pcr_idx,
 int tpm2_pcr_extend(struct tpm_chip *chip, u32 pcr_idx,
 		    struct tpm_digest *digests)
 {
-	struct tpm_buf buf;
 	int rc;
 	int i;
 
+	struct tpm_buf *buf __free(kfree) = kzalloc(PAGE_SIZE, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
 	if (!disable_pcr_integrity) {
 		rc = tpm2_start_auth_session(chip);
 		if (rc)
 			return rc;
 	}
 
-	rc = tpm_buf_init(&buf, TPM2_ST_SESSIONS, TPM2_CC_PCR_EXTEND);
-	if (rc) {
-		if (!disable_pcr_integrity)
-			tpm2_end_auth_session(chip);
-		return rc;
-	}
+	tpm_buf_reset(buf, PAGE_SIZE, TPM2_ST_SESSIONS, TPM2_CC_PCR_EXTEND);
 
 	if (!disable_pcr_integrity) {
-		tpm_buf_append_name(chip, &buf, pcr_idx, NULL);
-		tpm_buf_append_hmac_session(chip, &buf, 0, NULL, 0);
+		tpm_buf_append_name(chip, buf, pcr_idx, NULL);
+		tpm_buf_append_hmac_session(chip, buf, 0, NULL, 0);
 	} else {
-		tpm_buf_append_handle(chip, &buf, pcr_idx);
-		tpm_buf_append_auth(chip, &buf, 0, NULL, 0);
+		tpm_buf_append_handle(chip, buf, pcr_idx);
+		tpm_buf_append_auth(chip, buf, 0, NULL, 0);
 	}
 
-	tpm_buf_append_u32(&buf, chip->nr_allocated_banks);
+	tpm_buf_append_u32(buf, chip->nr_allocated_banks);
 
 	for (i = 0; i < chip->nr_allocated_banks; i++) {
-		tpm_buf_append_u16(&buf, digests[i].alg_id);
-		tpm_buf_append(&buf, (const unsigned char *)&digests[i].digest,
+		tpm_buf_append_u16(buf, digests[i].alg_id);
+		tpm_buf_append(buf, (const unsigned char *)&digests[i].digest,
 			       chip->allocated_banks[i].digest_size);
 	}
 
 	if (!disable_pcr_integrity)
-		tpm_buf_fill_hmac_session(chip, &buf);
-	rc = tpm_transmit_cmd(chip, &buf, 0, "attempting extend a PCR value");
+		tpm_buf_fill_hmac_session(chip, buf);
+	rc = tpm_transmit_cmd(chip, buf, 0, "attempting extend a PCR value");
 	if (!disable_pcr_integrity)
-		rc = tpm_buf_check_hmac_response(chip, &buf, rc);
-
-	tpm_buf_destroy(&buf);
+		rc = tpm_buf_check_hmac_response(chip, buf, rc);
 
 	return rc;
 }
@@ -296,7 +289,6 @@ int tpm2_get_random(struct tpm_chip *chip, u8 *dest, size_t max)
 {
 	struct tpm2_get_random_out *out;
 	struct tpm_header *head;
-	struct tpm_buf buf;
 	u32 recd;
 	u32 num_bytes = max;
 	int err;
@@ -308,43 +300,41 @@ int tpm2_get_random(struct tpm_chip *chip, u8 *dest, size_t max)
 	if (!num_bytes || max > TPM_MAX_RNG_DATA)
 		return -EINVAL;
 
+	struct tpm_buf *buf __free(kfree) = kzalloc(PAGE_SIZE, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
 	err = tpm2_start_auth_session(chip);
 	if (err)
 		return err;
 
-	err = tpm_buf_init(&buf, 0, 0);
-	if (err) {
-		tpm2_end_auth_session(chip);
-		return err;
-	}
-
 	do {
-		tpm_buf_reset(&buf, TPM2_ST_SESSIONS, TPM2_CC_GET_RANDOM);
-		tpm_buf_append_hmac_session_opt(chip, &buf, TPM2_SA_ENCRYPT
+		tpm_buf_reset(buf, PAGE_SIZE, TPM2_ST_SESSIONS, TPM2_CC_GET_RANDOM);
+		tpm_buf_append_hmac_session_opt(chip, buf, TPM2_SA_ENCRYPT
 						| TPM2_SA_CONTINUE_SESSION,
 						NULL, 0);
-		tpm_buf_append_u16(&buf, num_bytes);
-		tpm_buf_fill_hmac_session(chip, &buf);
-		err = tpm_transmit_cmd(chip, &buf,
+		tpm_buf_append_u16(buf, num_bytes);
+		tpm_buf_fill_hmac_session(chip, buf);
+		err = tpm_transmit_cmd(chip, buf,
 				       offsetof(struct tpm2_get_random_out,
 						buffer),
 				       "attempting get random");
-		err = tpm_buf_check_hmac_response(chip, &buf, err);
+		err = tpm_buf_check_hmac_response(chip, buf, err);
 		if (err) {
 			if (err > 0)
 				err = -EIO;
 			goto out;
 		}
 
-		head = (struct tpm_header *)buf.data;
+		head = (struct tpm_header *)buf->data;
 		offset = TPM_HEADER_SIZE;
 		/* Skip the parameter size field: */
 		if (be16_to_cpu(head->tag) == TPM2_ST_SESSIONS)
 			offset += 4;
 
-		out = (struct tpm2_get_random_out *)&buf.data[offset];
+		out = (struct tpm2_get_random_out *)&buf->data[offset];
 		recd = min_t(u32, be16_to_cpu(out->size), num_bytes);
-		if (tpm_buf_length(&buf) <
+		if (tpm_buf_length(buf) <
 		    TPM_HEADER_SIZE +
 		    offsetof(struct tpm2_get_random_out, buffer) +
 		    recd) {
@@ -358,11 +348,9 @@ int tpm2_get_random(struct tpm_chip *chip, u8 *dest, size_t max)
 		num_bytes -= recd;
 	} while (retries-- && total < max);
 
-	tpm_buf_destroy(&buf);
-
 	return total ? total : -EIO;
+
 out:
-	tpm_buf_destroy(&buf);
 	tpm2_end_auth_session(chip);
 	return err;
 }
@@ -374,20 +362,17 @@ int tpm2_get_random(struct tpm_chip *chip, u8 *dest, size_t max)
  */
 void tpm2_flush_context(struct tpm_chip *chip, u32 handle)
 {
-	struct tpm_buf buf;
-	int rc;
-
-	rc = tpm_buf_init(&buf, TPM2_ST_NO_SESSIONS, TPM2_CC_FLUSH_CONTEXT);
-	if (rc) {
+	struct tpm_buf *buf __free(kfree) = kzalloc(PAGE_SIZE, GFP_KERNEL);
+	if (!buf) {
 		dev_warn(&chip->dev, "0x%08x was not flushed, out of memory\n",
 			 handle);
 		return;
 	}
 
-	tpm_buf_append_u32(&buf, handle);
+	tpm_buf_reset(buf, PAGE_SIZE, TPM2_ST_NO_SESSIONS, TPM2_CC_FLUSH_CONTEXT);
+	tpm_buf_append_u32(buf, handle);
 
-	tpm_transmit_cmd(chip, &buf, 0, "flushing context");
-	tpm_buf_destroy(&buf);
+	tpm_transmit_cmd(chip, buf, 0, "flushing context");
 }
 EXPORT_SYMBOL_GPL(tpm2_flush_context);
 
@@ -414,19 +399,20 @@ ssize_t tpm2_get_tpm_pt(struct tpm_chip *chip, u32 property_id,  u32 *value,
 			const char *desc)
 {
 	struct tpm2_get_cap_out *out;
-	struct tpm_buf buf;
 	int rc;
 
-	rc = tpm_buf_init(&buf, TPM2_ST_NO_SESSIONS, TPM2_CC_GET_CAPABILITY);
-	if (rc)
-		return rc;
-	tpm_buf_append_u32(&buf, TPM2_CAP_TPM_PROPERTIES);
-	tpm_buf_append_u32(&buf, property_id);
-	tpm_buf_append_u32(&buf, 1);
-	rc = tpm_transmit_cmd(chip, &buf, 0, NULL);
+	struct tpm_buf *buf __free(kfree) = kzalloc(PAGE_SIZE, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	tpm_buf_reset(buf, PAGE_SIZE, TPM2_ST_NO_SESSIONS, TPM2_CC_GET_CAPABILITY);
+	tpm_buf_append_u32(buf, TPM2_CAP_TPM_PROPERTIES);
+	tpm_buf_append_u32(buf, property_id);
+	tpm_buf_append_u32(buf, 1);
+	rc = tpm_transmit_cmd(chip, buf, 0, NULL);
 	if (!rc) {
 		out = (struct tpm2_get_cap_out *)
-			&buf.data[TPM_HEADER_SIZE];
+			&buf->data[TPM_HEADER_SIZE];
 		/*
 		 * To prevent failing boot up of some systems, Infineon TPM2.0
 		 * returns SUCCESS on TPM2_Startup in field upgrade mode. Also
@@ -438,7 +424,6 @@ ssize_t tpm2_get_tpm_pt(struct tpm_chip *chip, u32 property_id,  u32 *value,
 		else
 			rc = -ENODATA;
 	}
-	tpm_buf_destroy(&buf);
 	return rc;
 }
 EXPORT_SYMBOL_GPL(tpm2_get_tpm_pt);
@@ -455,15 +440,13 @@ EXPORT_SYMBOL_GPL(tpm2_get_tpm_pt);
  */
 void tpm2_shutdown(struct tpm_chip *chip, u16 shutdown_type)
 {
-	struct tpm_buf buf;
-	int rc;
-
-	rc = tpm_buf_init(&buf, TPM2_ST_NO_SESSIONS, TPM2_CC_SHUTDOWN);
-	if (rc)
+	struct tpm_buf *buf __free(kfree) = kzalloc(PAGE_SIZE, GFP_KERNEL);
+	if (!buf)
 		return;
-	tpm_buf_append_u16(&buf, shutdown_type);
-	tpm_transmit_cmd(chip, &buf, 0, "stopping the TPM");
-	tpm_buf_destroy(&buf);
+
+	tpm_buf_reset(buf, PAGE_SIZE, TPM2_ST_NO_SESSIONS, TPM2_CC_SHUTDOWN);
+	tpm_buf_append_u16(buf, shutdown_type);
+	tpm_transmit_cmd(chip, buf, 0, "stopping the TPM");
 }
 
 /**
@@ -481,19 +464,18 @@ void tpm2_shutdown(struct tpm_chip *chip, u16 shutdown_type)
  */
 static int tpm2_do_selftest(struct tpm_chip *chip)
 {
-	struct tpm_buf buf;
 	int full;
 	int rc;
 
-	for (full = 0; full < 2; full++) {
-		rc = tpm_buf_init(&buf, TPM2_ST_NO_SESSIONS, TPM2_CC_SELF_TEST);
-		if (rc)
-			return rc;
+	struct tpm_buf *buf __free(kfree) = kzalloc(PAGE_SIZE, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
 
-		tpm_buf_append_u8(&buf, full);
-		rc = tpm_transmit_cmd(chip, &buf, 0,
+	for (full = 0; full < 2; full++) {
+		tpm_buf_reset(buf, PAGE_SIZE, TPM2_ST_NO_SESSIONS, TPM2_CC_SELF_TEST);
+		tpm_buf_append_u8(buf, full);
+		rc = tpm_transmit_cmd(chip, buf, 0,
 				      "attempting the self test");
-		tpm_buf_destroy(&buf);
 
 		if (rc == TPM2_RC_TESTING)
 			rc = TPM2_RC_SUCCESS;
@@ -519,23 +501,23 @@ static int tpm2_do_selftest(struct tpm_chip *chip)
 int tpm2_probe(struct tpm_chip *chip)
 {
 	struct tpm_header *out;
-	struct tpm_buf buf;
 	int rc;
 
-	rc = tpm_buf_init(&buf, TPM2_ST_NO_SESSIONS, TPM2_CC_GET_CAPABILITY);
-	if (rc)
-		return rc;
-	tpm_buf_append_u32(&buf, TPM2_CAP_TPM_PROPERTIES);
-	tpm_buf_append_u32(&buf, TPM_PT_TOTAL_COMMANDS);
-	tpm_buf_append_u32(&buf, 1);
-	rc = tpm_transmit_cmd(chip, &buf, 0, NULL);
+	struct tpm_buf *buf __free(kfree) = kzalloc(PAGE_SIZE, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	tpm_buf_reset(buf, PAGE_SIZE, TPM2_ST_NO_SESSIONS, TPM2_CC_GET_CAPABILITY);
+	tpm_buf_append_u32(buf, TPM2_CAP_TPM_PROPERTIES);
+	tpm_buf_append_u32(buf, TPM_PT_TOTAL_COMMANDS);
+	tpm_buf_append_u32(buf, 1);
+	rc = tpm_transmit_cmd(chip, buf, 0, NULL);
 	/* We ignore TPM return codes on purpose. */
 	if (rc >=  0) {
-		out = (struct tpm_header *)buf.data;
+		out = (struct tpm_header *)buf->data;
 		if (be16_to_cpu(out->tag) == TPM2_ST_NO_SESSIONS)
 			chip->flags |= TPM_CHIP_FLAG_TPM2;
 	}
-	tpm_buf_destroy(&buf);
 	return 0;
 }
 EXPORT_SYMBOL_GPL(tpm2_probe);
@@ -575,7 +557,6 @@ struct tpm2_pcr_selection {
 ssize_t tpm2_get_pcr_allocation(struct tpm_chip *chip)
 {
 	struct tpm2_pcr_selection pcr_selection;
-	struct tpm_buf buf;
 	void *marker;
 	void *end;
 	void *pcr_select_offset;
@@ -587,41 +568,38 @@ ssize_t tpm2_get_pcr_allocation(struct tpm_chip *chip)
 	int rc;
 	int i = 0;
 
-	rc = tpm_buf_init(&buf, TPM2_ST_NO_SESSIONS, TPM2_CC_GET_CAPABILITY);
-	if (rc)
-		return rc;
+	struct tpm_buf *buf __free(kfree) = kzalloc(PAGE_SIZE, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
 
-	tpm_buf_append_u32(&buf, TPM2_CAP_PCRS);
-	tpm_buf_append_u32(&buf, 0);
-	tpm_buf_append_u32(&buf, 1);
+	tpm_buf_reset(buf, PAGE_SIZE, TPM2_ST_NO_SESSIONS, TPM2_CC_GET_CAPABILITY);
+	tpm_buf_append_u32(buf, TPM2_CAP_PCRS);
+	tpm_buf_append_u32(buf, 0);
+	tpm_buf_append_u32(buf, 1);
 
-	rc = tpm_transmit_cmd(chip, &buf, 9, "get tpm pcr allocation");
+	rc = tpm_transmit_cmd(chip, buf, 9, "get tpm pcr allocation");
 	if (rc)
-		goto out;
+		return rc;
 
 	nr_possible_banks = be32_to_cpup(
-		(__be32 *)&buf.data[TPM_HEADER_SIZE + 5]);
+		(__be32 *)&buf->data[TPM_HEADER_SIZE + 5]);
 
 	chip->allocated_banks = kcalloc(nr_possible_banks,
 					sizeof(*chip->allocated_banks),
 					GFP_KERNEL);
-	if (!chip->allocated_banks) {
-		rc = -ENOMEM;
-		goto out;
-	}
+	if (!chip->allocated_banks)
+		return -ENOMEM;
 
-	marker = &buf.data[TPM_HEADER_SIZE + 9];
+	marker = &buf->data[TPM_HEADER_SIZE + 9];
 
-	rsp_len = be32_to_cpup((__be32 *)&buf.data[2]);
-	end = &buf.data[rsp_len];
+	rsp_len = be32_to_cpup((__be32 *)&buf->data[2]);
+	end = &buf->data[rsp_len];
 
 	for (i = 0; i < nr_possible_banks; i++) {
 		pcr_select_offset = marker +
 			offsetof(struct tpm2_pcr_selection, size_of_select);
-		if (pcr_select_offset >= end) {
-			rc = -EFAULT;
-			break;
-		}
+		if (pcr_select_offset >= end)
+			return -EFAULT;
 
 		memcpy(&pcr_selection, marker, sizeof(pcr_selection));
 		hash_alg = be16_to_cpu(pcr_selection.hash_alg);
@@ -633,7 +611,7 @@ ssize_t tpm2_get_pcr_allocation(struct tpm_chip *chip)
 
 			rc = tpm2_init_bank_info(chip, nr_alloc_banks);
 			if (rc < 0)
-				break;
+				return rc;
 
 			nr_alloc_banks++;
 		}
@@ -645,21 +623,21 @@ ssize_t tpm2_get_pcr_allocation(struct tpm_chip *chip)
 	}
 
 	chip->nr_allocated_banks = nr_alloc_banks;
-out:
-	tpm_buf_destroy(&buf);
-
-	return rc;
+	return 0;
 }
 
 int tpm2_get_cc_attrs_tbl(struct tpm_chip *chip)
 {
-	struct tpm_buf buf;
 	u32 nr_commands;
 	__be32 *attrs;
 	u32 cc;
 	int i;
 	int rc;
 
+	struct tpm_buf *buf __free(kfree) = kzalloc(PAGE_SIZE, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
 	rc = tpm2_get_tpm_pt(chip, TPM_PT_TOTAL_COMMANDS, &nr_commands, NULL);
 	if (rc)
 		goto out;
@@ -676,30 +654,24 @@ int tpm2_get_cc_attrs_tbl(struct tpm_chip *chip)
 		goto out;
 	}
 
-	rc = tpm_buf_init(&buf, TPM2_ST_NO_SESSIONS, TPM2_CC_GET_CAPABILITY);
-	if (rc)
-		goto out;
-
-	tpm_buf_append_u32(&buf, TPM2_CAP_COMMANDS);
-	tpm_buf_append_u32(&buf, TPM2_CC_FIRST);
-	tpm_buf_append_u32(&buf, nr_commands);
+	tpm_buf_reset(buf, PAGE_SIZE, TPM2_ST_NO_SESSIONS, TPM2_CC_GET_CAPABILITY);
+	tpm_buf_append_u32(buf, TPM2_CAP_COMMANDS);
+	tpm_buf_append_u32(buf, TPM2_CC_FIRST);
+	tpm_buf_append_u32(buf, nr_commands);
 
-	rc = tpm_transmit_cmd(chip, &buf, 9 + 4 * nr_commands, NULL);
-	if (rc) {
-		tpm_buf_destroy(&buf);
+	rc = tpm_transmit_cmd(chip, buf, 9 + 4 * nr_commands, NULL);
+	if (rc)
 		goto out;
-	}
 
 	if (nr_commands !=
-	    be32_to_cpup((__be32 *)&buf.data[TPM_HEADER_SIZE + 5])) {
+	    be32_to_cpup((__be32 *)&buf->data[TPM_HEADER_SIZE + 5])) {
 		rc = -EFAULT;
-		tpm_buf_destroy(&buf);
 		goto out;
 	}
 
 	chip->nr_commands = nr_commands;
 
-	attrs = (__be32 *)&buf.data[TPM_HEADER_SIZE + 9];
+	attrs = (__be32 *)&buf->data[TPM_HEADER_SIZE + 9];
 	for (i = 0; i < nr_commands; i++, attrs++) {
 		chip->cc_attrs_tbl[i] = be32_to_cpup(attrs);
 		cc = chip->cc_attrs_tbl[i] & 0xFFFF;
@@ -711,8 +683,6 @@ int tpm2_get_cc_attrs_tbl(struct tpm_chip *chip)
 		}
 	}
 
-	tpm_buf_destroy(&buf);
-
 out:
 	if (rc > 0)
 		rc = -ENODEV;
@@ -733,20 +703,16 @@ EXPORT_SYMBOL_GPL(tpm2_get_cc_attrs_tbl);
 
 static int tpm2_startup(struct tpm_chip *chip)
 {
-	struct tpm_buf buf;
-	int rc;
+	struct tpm_buf *buf __free(kfree) = kzalloc(PAGE_SIZE, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
 
 	dev_info(&chip->dev, "starting up the TPM manually\n");
 
-	rc = tpm_buf_init(&buf, TPM2_ST_NO_SESSIONS, TPM2_CC_STARTUP);
-	if (rc < 0)
-		return rc;
-
-	tpm_buf_append_u16(&buf, TPM2_SU_CLEAR);
-	rc = tpm_transmit_cmd(chip, &buf, 0, "attempting to start the TPM");
-	tpm_buf_destroy(&buf);
+	tpm_buf_reset(buf, PAGE_SIZE, TPM2_ST_NO_SESSIONS, TPM2_CC_STARTUP);
+	tpm_buf_append_u16(buf, TPM2_SU_CLEAR);
 
-	return rc;
+	return tpm_transmit_cmd(chip, buf, 0, "attempting to start the TPM");
 }
 
 /**
diff --git a/drivers/char/tpm/tpm2-sessions.c b/drivers/char/tpm/tpm2-sessions.c
index 6d03c224e6b2..b2c0c2143adc 100644
--- a/drivers/char/tpm/tpm2-sessions.c
+++ b/drivers/char/tpm/tpm2-sessions.c
@@ -182,19 +182,17 @@ static int tpm2_parse_read_public(char *name, struct tpm_buf *buf)
 
 static int tpm2_read_public(struct tpm_chip *chip, u32 handle, char *name)
 {
-	struct tpm_buf buf;
 	int rc;
 
-	rc = tpm_buf_init(&buf, TPM2_ST_NO_SESSIONS, TPM2_CC_READ_PUBLIC);
-	if (rc)
-		return rc;
+	struct tpm_buf *buf __free(kfree) = kzalloc(PAGE_SIZE, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
 
-	tpm_buf_append_u32(&buf, handle);
-	rc = tpm_transmit_cmd(chip, &buf, 0, "read public");
+	tpm_buf_reset(buf, PAGE_SIZE, TPM2_ST_NO_SESSIONS, TPM2_CC_READ_PUBLIC);
+	tpm_buf_append_u32(buf, handle);
+	rc = tpm_transmit_cmd(chip, buf, 0, "read public");
 	if (rc == TPM2_RC_SUCCESS)
-		rc = tpm2_parse_read_public(name, &buf);
-
-	tpm_buf_destroy(&buf);
+		rc = tpm2_parse_read_public(name, buf);
 
 	return rc;
 }
@@ -925,7 +923,6 @@ static int tpm2_load_null(struct tpm_chip *chip, u32 *null_key)
 int tpm2_start_auth_session(struct tpm_chip *chip)
 {
 	struct tpm2_auth *auth;
-	struct tpm_buf buf;
 	u32 null_key;
 	int rc;
 
@@ -934,6 +931,10 @@ int tpm2_start_auth_session(struct tpm_chip *chip)
 		return 0;
 	}
 
+	struct tpm_buf *buf __free(kfree) = kzalloc(PAGE_SIZE, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
 	auth = kzalloc(sizeof(*auth), GFP_KERNEL);
 	if (!auth)
 		return -ENOMEM;
@@ -944,41 +945,36 @@ int tpm2_start_auth_session(struct tpm_chip *chip)
 
 	auth->session = TPM_HEADER_SIZE;
 
-	rc = tpm_buf_init(&buf, TPM2_ST_NO_SESSIONS, TPM2_CC_START_AUTH_SESS);
-	if (rc)
-		goto out;
-
+	tpm_buf_reset(buf, PAGE_SIZE, TPM2_ST_NO_SESSIONS, TPM2_CC_START_AUTH_SESS);
 	/* salt key handle */
-	tpm_buf_append_u32(&buf, null_key);
+	tpm_buf_append_u32(buf, null_key);
 	/* bind key handle */
-	tpm_buf_append_u32(&buf, TPM2_RH_NULL);
+	tpm_buf_append_u32(buf, TPM2_RH_NULL);
 	/* nonce caller */
 	get_random_bytes(auth->our_nonce, sizeof(auth->our_nonce));
-	tpm_buf_append_u16(&buf, sizeof(auth->our_nonce));
-	tpm_buf_append(&buf, auth->our_nonce, sizeof(auth->our_nonce));
+	tpm_buf_append_u16(buf, sizeof(auth->our_nonce));
+	tpm_buf_append(buf, auth->our_nonce, sizeof(auth->our_nonce));
 
 	/* append encrypted salt and squirrel away unencrypted in auth */
-	tpm_buf_append_salt(&buf, chip, auth);
+	tpm_buf_append_salt(buf, chip, auth);
 	/* session type (HMAC, audit or policy) */
-	tpm_buf_append_u8(&buf, TPM2_SE_HMAC);
+	tpm_buf_append_u8(buf, TPM2_SE_HMAC);
 
 	/* symmetric encryption parameters */
 	/* symmetric algorithm */
-	tpm_buf_append_u16(&buf, TPM_ALG_AES);
+	tpm_buf_append_u16(buf, TPM_ALG_AES);
 	/* bits for symmetric algorithm */
-	tpm_buf_append_u16(&buf, AES_KEY_BITS);
+	tpm_buf_append_u16(buf, AES_KEY_BITS);
 	/* symmetric algorithm mode (must be CFB) */
-	tpm_buf_append_u16(&buf, TPM_ALG_CFB);
+	tpm_buf_append_u16(buf, TPM_ALG_CFB);
 	/* hash algorithm for session */
-	tpm_buf_append_u16(&buf, TPM_ALG_SHA256);
+	tpm_buf_append_u16(buf, TPM_ALG_SHA256);
 
-	rc = tpm_ret_to_err(tpm_transmit_cmd(chip, &buf, 0, "StartAuthSession"));
+	rc = tpm_ret_to_err(tpm_transmit_cmd(chip, buf, 0, "StartAuthSession"));
 	tpm2_flush_context(chip, null_key);
 
 	if (rc == TPM2_RC_SUCCESS)
-		rc = tpm2_parse_start_auth_session(auth, &buf);
-
-	tpm_buf_destroy(&buf);
+		rc = tpm2_parse_start_auth_session(auth, buf);
 
 	if (rc == TPM2_RC_SUCCESS) {
 		chip->auth = auth;
@@ -1200,18 +1196,17 @@ static int tpm2_create_primary(struct tpm_chip *chip, u32 hierarchy,
 			       u32 *handle, u8 *name)
 {
 	int rc;
-	struct tpm_buf buf;
-	struct tpm_buf template;
 
-	rc = tpm_buf_init(&buf, TPM2_ST_SESSIONS, TPM2_CC_CREATE_PRIMARY);
-	if (rc)
-		return rc;
+	struct tpm_buf *buf __free(kfree) = kzalloc(PAGE_SIZE, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
 
-	rc = tpm_buf_init_sized(&template);
-	if (rc) {
-		tpm_buf_destroy(&buf);
-		return rc;
-	}
+	struct tpm_buf *template __free(kfree) = kzalloc(PAGE_SIZE, GFP_KERNEL);
+	if (!template)
+		return -ENOMEM;
+
+	tpm_buf_reset(buf, PAGE_SIZE, TPM2_ST_SESSIONS, TPM2_CC_CREATE_PRIMARY);
+	tpm_buf_reset_sized(template, PAGE_SIZE);
 
 	/*
 	 * create the template.  Note: in order for userspace to
@@ -1223,75 +1218,72 @@ static int tpm2_create_primary(struct tpm_chip *chip, u32 hierarchy,
 	 */
 
 	/* key type */
-	tpm_buf_append_u16(&template, TPM_ALG_ECC);
+	tpm_buf_append_u16(template, TPM_ALG_ECC);
 
 	/* name algorithm */
-	tpm_buf_append_u16(&template, TPM_ALG_SHA256);
+	tpm_buf_append_u16(template, TPM_ALG_SHA256);
 
 	/* object properties */
-	tpm_buf_append_u32(&template, TPM2_OA_NULL_KEY);
+	tpm_buf_append_u32(template, TPM2_OA_NULL_KEY);
 
 	/* sauth policy (empty) */
-	tpm_buf_append_u16(&template, 0);
+	tpm_buf_append_u16(template, 0);
 
 	/* BEGIN parameters: key specific; for ECC*/
 
 	/* symmetric algorithm */
-	tpm_buf_append_u16(&template, TPM_ALG_AES);
+	tpm_buf_append_u16(template, TPM_ALG_AES);
 
 	/* bits for symmetric algorithm */
-	tpm_buf_append_u16(&template, AES_KEY_BITS);
+	tpm_buf_append_u16(template, AES_KEY_BITS);
 
 	/* algorithm mode (must be CFB) */
-	tpm_buf_append_u16(&template, TPM_ALG_CFB);
+	tpm_buf_append_u16(template, TPM_ALG_CFB);
 
 	/* scheme (NULL means any scheme) */
-	tpm_buf_append_u16(&template, TPM_ALG_NULL);
+	tpm_buf_append_u16(template, TPM_ALG_NULL);
 
 	/* ECC Curve ID */
-	tpm_buf_append_u16(&template, TPM2_ECC_NIST_P256);
+	tpm_buf_append_u16(template, TPM2_ECC_NIST_P256);
 
 	/* KDF Scheme */
-	tpm_buf_append_u16(&template, TPM_ALG_NULL);
+	tpm_buf_append_u16(template, TPM_ALG_NULL);
 
 	/* unique: key specific; for ECC it is two zero size points */
-	tpm_buf_append_u16(&template, 0);
-	tpm_buf_append_u16(&template, 0);
+	tpm_buf_append_u16(template, 0);
+	tpm_buf_append_u16(template, 0);
 
 	/* END parameters */
 
 	/* primary handle */
-	tpm_buf_append_u32(&buf, hierarchy);
-	tpm_buf_append_empty_auth(&buf, TPM2_RS_PW);
+	tpm_buf_append_u32(buf, hierarchy);
+	tpm_buf_append_empty_auth(buf, TPM2_RS_PW);
 
 	/* sensitive create size is 4 for two empty buffers */
-	tpm_buf_append_u16(&buf, 4);
+	tpm_buf_append_u16(buf, 4);
 
 	/* sensitive create auth data (empty) */
-	tpm_buf_append_u16(&buf, 0);
+	tpm_buf_append_u16(buf, 0);
 
 	/* sensitive create sensitive data (empty) */
-	tpm_buf_append_u16(&buf, 0);
+	tpm_buf_append_u16(buf, 0);
 
 	/* the public template */
-	tpm_buf_append(&buf, template.data, template.length);
-	tpm_buf_destroy(&template);
+	tpm_buf_append(buf, template->data, template->length);
 
 	/* outside info (empty) */
-	tpm_buf_append_u16(&buf, 0);
+	tpm_buf_append_u16(buf, 0);
 
 	/* creation PCR (none) */
-	tpm_buf_append_u32(&buf, 0);
+	tpm_buf_append_u32(buf, 0);
 
-	rc = tpm_transmit_cmd(chip, &buf, 0,
+	rc = tpm_transmit_cmd(chip, buf, 0,
 			      "attempting to create NULL primary");
 
 	if (rc == TPM2_RC_SUCCESS)
-		rc = tpm2_parse_create_primary(chip, &buf, handle, hierarchy,
+		rc = tpm2_parse_create_primary(chip, buf, handle, hierarchy,
 					       name);
 
-	tpm_buf_destroy(&buf);
-
 	return rc;
 }
 
diff --git a/drivers/char/tpm/tpm2-space.c b/drivers/char/tpm/tpm2-space.c
index 60354cd53b5c..c7409c4c78d0 100644
--- a/drivers/char/tpm/tpm2-space.c
+++ b/drivers/char/tpm/tpm2-space.c
@@ -71,24 +71,24 @@ void tpm2_del_space(struct tpm_chip *chip, struct tpm_space *space)
 int tpm2_load_context(struct tpm_chip *chip, u8 *buf,
 		      unsigned int *offset, u32 *handle)
 {
-	struct tpm_buf tbuf;
 	struct tpm2_context *ctx;
 	unsigned int body_size;
 	int rc;
 
-	rc = tpm_buf_init(&tbuf, TPM2_ST_NO_SESSIONS, TPM2_CC_CONTEXT_LOAD);
-	if (rc)
-		return rc;
+	struct tpm_buf *tbuf __free(kfree) = kzalloc(PAGE_SIZE, GFP_KERNEL);
+	if (!tbuf)
+		return -ENOMEM;
+
+	tpm_buf_reset(tbuf, PAGE_SIZE, TPM2_ST_NO_SESSIONS, TPM2_CC_CONTEXT_LOAD);
 
 	ctx = (struct tpm2_context *)&buf[*offset];
 	body_size = sizeof(*ctx) + be16_to_cpu(ctx->blob_size);
-	tpm_buf_append(&tbuf, &buf[*offset], body_size);
+	tpm_buf_append(tbuf, &buf[*offset], body_size);
 
-	rc = tpm_transmit_cmd(chip, &tbuf, 4, NULL);
+	rc = tpm_transmit_cmd(chip, tbuf, 4, NULL);
 	if (rc < 0) {
 		dev_warn(&chip->dev, "%s: failed with a system error %d\n",
 			 __func__, rc);
-		tpm_buf_destroy(&tbuf);
 		return -EFAULT;
 	} else if (tpm2_rc_value(rc) == TPM2_RC_HANDLE ||
 		   rc == TPM2_RC_REFERENCE_H0) {
@@ -103,64 +103,54 @@ int tpm2_load_context(struct tpm_chip *chip, u8 *buf,
 		 * flushed outside the space
 		 */
 		*handle = 0;
-		tpm_buf_destroy(&tbuf);
 		return -ENOENT;
 	} else if (tpm2_rc_value(rc) == TPM2_RC_INTEGRITY) {
-		tpm_buf_destroy(&tbuf);
 		return -EINVAL;
 	} else if (rc > 0) {
 		dev_warn(&chip->dev, "%s: failed with a TPM error 0x%04X\n",
 			 __func__, rc);
-		tpm_buf_destroy(&tbuf);
 		return -EFAULT;
 	}
 
-	*handle = be32_to_cpup((__be32 *)&tbuf.data[TPM_HEADER_SIZE]);
+	*handle = be32_to_cpup((__be32 *)&tbuf->data[TPM_HEADER_SIZE]);
 	*offset += body_size;
-
-	tpm_buf_destroy(&tbuf);
 	return 0;
 }
 
 int tpm2_save_context(struct tpm_chip *chip, u32 handle, u8 *buf,
 		      unsigned int buf_size, unsigned int *offset)
 {
-	struct tpm_buf tbuf;
 	unsigned int body_size;
 	int rc;
 
-	rc = tpm_buf_init(&tbuf, TPM2_ST_NO_SESSIONS, TPM2_CC_CONTEXT_SAVE);
-	if (rc)
-		return rc;
+	struct tpm_buf *tbuf __free(kfree) = kzalloc(PAGE_SIZE, GFP_KERNEL);
+	if (!tbuf)
+		return -ENOMEM;
 
-	tpm_buf_append_u32(&tbuf, handle);
+	tpm_buf_reset(tbuf, PAGE_SIZE, TPM2_ST_NO_SESSIONS, TPM2_CC_CONTEXT_SAVE);
+	tpm_buf_append_u32(tbuf, handle);
 
-	rc = tpm_transmit_cmd(chip, &tbuf, 0, NULL);
+	rc = tpm_transmit_cmd(chip, tbuf, 0, NULL);
 	if (rc < 0) {
 		dev_warn(&chip->dev, "%s: failed with a system error %d\n",
 			 __func__, rc);
-		tpm_buf_destroy(&tbuf);
 		return -EFAULT;
 	} else if (tpm2_rc_value(rc) == TPM2_RC_REFERENCE_H0) {
-		tpm_buf_destroy(&tbuf);
 		return -ENOENT;
 	} else if (rc) {
 		dev_warn(&chip->dev, "%s: failed with a TPM error 0x%04X\n",
 			 __func__, rc);
-		tpm_buf_destroy(&tbuf);
 		return -EFAULT;
 	}
 
-	body_size = tpm_buf_length(&tbuf) - TPM_HEADER_SIZE;
+	body_size = tpm_buf_length(tbuf) - TPM_HEADER_SIZE;
 	if ((*offset + body_size) > buf_size) {
 		dev_warn(&chip->dev, "%s: out of backing storage\n", __func__);
-		tpm_buf_destroy(&tbuf);
 		return -ENOMEM;
 	}
 
-	memcpy(&buf[*offset], &tbuf.data[TPM_HEADER_SIZE], body_size);
+	memcpy(&buf[*offset], &tbuf->data[TPM_HEADER_SIZE], body_size);
 	*offset += body_size;
-	tpm_buf_destroy(&tbuf);
 	return 0;
 }
 
diff --git a/drivers/char/tpm/tpm_vtpm_proxy.c b/drivers/char/tpm/tpm_vtpm_proxy.c
index 0818bb517805..7ebe55825215 100644
--- a/drivers/char/tpm/tpm_vtpm_proxy.c
+++ b/drivers/char/tpm/tpm_vtpm_proxy.c
@@ -395,40 +395,35 @@ 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)
 {
-	struct tpm_buf buf;
 	int rc;
 	const struct tpm_header *header;
 	struct proxy_dev *proxy_dev = dev_get_drvdata(&chip->dev);
 
+	struct tpm_buf *buf __free(kfree) = kzalloc(PAGE_SIZE, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
 	if (chip->flags & TPM_CHIP_FLAG_TPM2)
-		rc = tpm_buf_init(&buf, TPM2_ST_SESSIONS,
-				  TPM2_CC_SET_LOCALITY);
+		tpm_buf_reset(buf, PAGE_SIZE, TPM2_ST_SESSIONS, TPM2_CC_SET_LOCALITY);
 	else
-		rc = tpm_buf_init(&buf, TPM_TAG_RQU_COMMAND,
-				  TPM_ORD_SET_LOCALITY);
-	if (rc)
-		return rc;
-	tpm_buf_append_u8(&buf, locality);
+		tpm_buf_reset(buf, PAGE_SIZE, TPM_TAG_RQU_COMMAND, TPM_ORD_SET_LOCALITY);
+
+	tpm_buf_append_u8(buf, locality);
 
 	proxy_dev->state |= STATE_DRIVER_COMMAND;
 
-	rc = tpm_transmit_cmd(chip, &buf, 0, "attempting to set locality");
+	rc = tpm_transmit_cmd(chip, buf, 0, "attempting to set locality");
 
 	proxy_dev->state &= ~STATE_DRIVER_COMMAND;
 
-	if (rc < 0) {
-		locality = rc;
-		goto out;
-	}
+	if (rc < 0)
+		return rc;
 
-	header = (const struct tpm_header *)buf.data;
+	header = (const struct tpm_header *)buf->data;
 	rc = be32_to_cpu(header->return_code);
 	if (rc)
 		locality = -1;
 
-out:
-	tpm_buf_destroy(&buf);
-
 	return locality;
 }
 
diff --git a/include/linux/tpm.h b/include/linux/tpm.h
index b0e9eb5ef022..1d8b016dd6bc 100644
--- a/include/linux/tpm.h
+++ b/include/linux/tpm.h
@@ -375,13 +375,15 @@ enum tpm_buf_flags {
 };
 
 /*
- * A string buffer type for constructing TPM commands.
+ * A buffer for constructing and parsing TPM commands, responses and sized
+ * (TPM2B) buffers.
  */
 struct tpm_buf {
-	u32 flags;
-	u32 length;
-	u8 *data;
+	u8 flags;
 	u8 handles;
+	u16 length;
+	u16 capacity;
+	u8 data[];
 };
 
 enum tpm2_object_attributes {
@@ -412,11 +414,8 @@ struct tpm2_hash {
 	unsigned int tpm_id;
 };
 
-int tpm_buf_init(struct tpm_buf *buf, u16 tag, u32 ordinal);
-void tpm_buf_reset(struct tpm_buf *buf, u16 tag, u32 ordinal);
-int tpm_buf_init_sized(struct tpm_buf *buf);
-void tpm_buf_reset_sized(struct tpm_buf *buf);
-void tpm_buf_destroy(struct tpm_buf *buf);
+void tpm_buf_reset(struct tpm_buf *buf, u16 buf_size, u16 tag, u32 ordinal);
+void tpm_buf_reset_sized(struct tpm_buf *buf, u16 buf_size);
 u32 tpm_buf_length(struct tpm_buf *buf);
 void tpm_buf_append(struct tpm_buf *buf, const u8 *new_data, u16 new_length);
 void tpm_buf_append_u8(struct tpm_buf *buf, const u8 value);
diff --git a/security/keys/trusted-keys/trusted_tpm1.c b/security/keys/trusted-keys/trusted_tpm1.c
index 636acb66a4f6..3b710daff084 100644
--- a/security/keys/trusted-keys/trusted_tpm1.c
+++ b/security/keys/trusted-keys/trusted_tpm1.c
@@ -312,21 +312,23 @@ static int TSS_checkhmac2(unsigned char *buffer,
  */
 static int trusted_tpm_send(unsigned char *cmd, size_t buflen)
 {
-	struct tpm_buf buf;
 	int rc;
 
 	if (!chip)
 		return -ENODEV;
 
+	struct tpm_buf *buf __free(kfree) = kzalloc(PAGE_SIZE, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
 	rc = tpm_try_get_ops(chip);
 	if (rc)
 		return rc;
 
-	buf.flags = 0;
-	buf.length = buflen;
-	buf.data = cmd;
+	tpm_buf_append(buf, cmd, buflen);
+
 	dump_tpm_buf(cmd);
-	rc = tpm_transmit_cmd(chip, &buf, 4, "sending data");
+	rc = tpm_transmit_cmd(chip, buf, 4, "sending data");
 	dump_tpm_buf(cmd);
 
 	if (rc > 0)
@@ -368,7 +370,7 @@ static int osap(struct tpm_buf *tb, struct osapsess *s,
 	if (ret != TPM_NONCE_SIZE)
 		return -EIO;
 
-	tpm_buf_reset(tb, TPM_TAG_RQU_COMMAND, TPM_ORD_OSAP);
+	tpm_buf_reset(tb, PAGE_SIZE, TPM_TAG_RQU_COMMAND, TPM_ORD_OSAP);
 	tpm_buf_append_u16(tb, type);
 	tpm_buf_append_u32(tb, handle);
 	tpm_buf_append(tb, ononce, TPM_NONCE_SIZE);
@@ -396,7 +398,7 @@ static int oiap(struct tpm_buf *tb, uint32_t *handle, unsigned char *nonce)
 	if (!chip)
 		return -ENODEV;
 
-	tpm_buf_reset(tb, TPM_TAG_RQU_COMMAND, TPM_ORD_OIAP);
+	tpm_buf_reset(tb, PAGE_SIZE, TPM_TAG_RQU_COMMAND, TPM_ORD_OIAP);
 	ret = trusted_tpm_send(tb->data, tb->length);
 	if (ret < 0)
 		return ret;
@@ -494,7 +496,7 @@ static int tpm_seal(struct tpm_buf *tb, uint16_t keytype,
 		goto out;
 
 	/* build and send the TPM request packet */
-	tpm_buf_reset(tb, TPM_TAG_RQU_AUTH1_COMMAND, TPM_ORD_SEAL);
+	tpm_buf_reset(tb, PAGE_SIZE, TPM_TAG_RQU_AUTH1_COMMAND, TPM_ORD_SEAL);
 	tpm_buf_append_u32(tb, keyhandle);
 	tpm_buf_append(tb, td->encauth, SHA1_DIGEST_SIZE);
 	tpm_buf_append_u32(tb, pcrinfosize);
@@ -585,7 +587,7 @@ static int tpm_unseal(struct tpm_buf *tb,
 		return ret;
 
 	/* build and send TPM request packet */
-	tpm_buf_reset(tb, TPM_TAG_RQU_AUTH2_COMMAND, TPM_ORD_UNSEAL);
+	tpm_buf_reset(tb, PAGE_SIZE, TPM_TAG_RQU_AUTH2_COMMAND, TPM_ORD_UNSEAL);
 	tpm_buf_append_u32(tb, keyhandle);
 	tpm_buf_append(tb, blob, bloblen);
 	tpm_buf_append_u32(tb, authhandle1);
@@ -624,23 +626,21 @@ static int tpm_unseal(struct tpm_buf *tb,
 static int key_seal(struct trusted_key_payload *p,
 		    struct trusted_key_options *o)
 {
-	struct tpm_buf tb;
 	int ret;
 
-	ret = tpm_buf_init(&tb, 0, 0);
-	if (ret)
-		return ret;
+	struct tpm_buf *tb __free(kfree) = kzalloc(PAGE_SIZE, GFP_KERNEL);
+	if (!tb)
+		return -ENOMEM;
 
 	/* include migratable flag at end of sealed key */
 	p->key[p->key_len] = p->migratable;
 
-	ret = tpm_seal(&tb, o->keytype, o->keyhandle, o->keyauth,
+	ret = tpm_seal(tb, o->keytype, o->keyhandle, o->keyauth,
 		       p->key, p->key_len + 1, p->blob, &p->blob_len,
 		       o->blobauth, o->pcrinfo, o->pcrinfo_len);
 	if (ret < 0)
 		pr_info("srkseal failed (%d)\n", ret);
 
-	tpm_buf_destroy(&tb);
 	return ret;
 }
 
@@ -650,14 +650,13 @@ static int key_seal(struct trusted_key_payload *p,
 static int key_unseal(struct trusted_key_payload *p,
 		      struct trusted_key_options *o)
 {
-	struct tpm_buf tb;
 	int ret;
 
-	ret = tpm_buf_init(&tb, 0, 0);
-	if (ret)
-		return ret;
+	struct tpm_buf *tb __free(kfree) = kzalloc(PAGE_SIZE, GFP_KERNEL);
+	if (!tb)
+		return -ENOMEM;
 
-	ret = tpm_unseal(&tb, o->keyhandle, o->keyauth, p->blob, p->blob_len,
+	ret = tpm_unseal(tb, o->keyhandle, o->keyauth, p->blob, p->blob_len,
 			 o->blobauth, p->key, &p->key_len);
 	if (ret < 0)
 		pr_info("srkunseal failed (%d)\n", ret);
@@ -665,7 +664,6 @@ static int key_unseal(struct trusted_key_payload *p,
 		/* pull migratable flag out of sealed key */
 		p->migratable = p->key[--p->key_len];
 
-	tpm_buf_destroy(&tb);
 	return ret;
 }
 
diff --git a/security/keys/trusted-keys/trusted_tpm2.c b/security/keys/trusted-keys/trusted_tpm2.c
index 024be262702f..472344c788ec 100644
--- a/security/keys/trusted-keys/trusted_tpm2.c
+++ b/security/keys/trusted-keys/trusted_tpm2.c
@@ -242,13 +242,20 @@ int tpm2_seal_trusted(struct tpm_chip *chip,
 		      struct trusted_key_options *options)
 {
 	off_t offset = TPM_HEADER_SIZE;
-	struct tpm_buf buf, sized;
 	int blob_len = 0;
 	u32 hash;
 	u32 flags;
 	int i;
 	int rc;
 
+	struct tpm_buf *buf __free(kfree) = kzalloc(PAGE_SIZE, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	struct tpm_buf *sized __free(kfree) = kzalloc(PAGE_SIZE, GFP_KERNEL);
+	if (!sized)
+		return -ENOMEM;
+
 	for (i = 0; i < ARRAY_SIZE(tpm2_hash_map); i++) {
 		if (options->hash == tpm2_hash_map[i].crypto_id) {
 			hash = tpm2_hash_map[i].tpm_id;
@@ -270,89 +277,76 @@ int tpm2_seal_trusted(struct tpm_chip *chip,
 	if (rc)
 		goto out_put;
 
-	rc = tpm_buf_init(&buf, TPM2_ST_SESSIONS, TPM2_CC_CREATE);
-	if (rc) {
-		tpm2_end_auth_session(chip);
-		goto out_put;
-	}
-
-	rc = tpm_buf_init_sized(&sized);
-	if (rc) {
-		tpm_buf_destroy(&buf);
-		tpm2_end_auth_session(chip);
-		goto out_put;
-	}
-
-	tpm_buf_append_name(chip, &buf, options->keyhandle, NULL);
-	tpm_buf_append_hmac_session(chip, &buf, TPM2_SA_DECRYPT,
+	tpm_buf_reset(buf, PAGE_SIZE, TPM2_ST_SESSIONS, TPM2_CC_CREATE);
+	tpm_buf_reset_sized(sized, PAGE_SIZE);
+	tpm_buf_append_name(chip, buf, options->keyhandle, NULL);
+	tpm_buf_append_hmac_session(chip, buf, TPM2_SA_DECRYPT,
 				    options->keyauth, TPM_DIGEST_SIZE);
 
 	/* sensitive */
-	tpm_buf_append_u16(&sized, options->blobauth_len);
+	tpm_buf_append_u16(sized, options->blobauth_len);
 
 	if (options->blobauth_len)
-		tpm_buf_append(&sized, options->blobauth, options->blobauth_len);
+		tpm_buf_append(sized, options->blobauth, options->blobauth_len);
 
-	tpm_buf_append_u16(&sized, payload->key_len);
-	tpm_buf_append(&sized, payload->key, payload->key_len);
-	tpm_buf_append(&buf, sized.data, sized.length);
+	tpm_buf_append_u16(sized, payload->key_len);
+	tpm_buf_append(sized, payload->key, payload->key_len);
+	tpm_buf_append(buf, sized->data, sized->length);
 
 	/* public */
-	tpm_buf_reset_sized(&sized);
-	tpm_buf_append_u16(&sized, TPM_ALG_KEYEDHASH);
-	tpm_buf_append_u16(&sized, hash);
+	tpm_buf_reset_sized(sized, PAGE_SIZE);
+	tpm_buf_append_u16(sized, TPM_ALG_KEYEDHASH);
+	tpm_buf_append_u16(sized, hash);
 
 	/* key properties */
 	flags = 0;
 	flags |= options->policydigest_len ? 0 : TPM2_OA_USER_WITH_AUTH;
 	flags |= payload->migratable ? 0 : (TPM2_OA_FIXED_TPM | TPM2_OA_FIXED_PARENT);
-	tpm_buf_append_u32(&sized, flags);
+	tpm_buf_append_u32(sized, flags);
 
 	/* policy */
-	tpm_buf_append_u16(&sized, options->policydigest_len);
+	tpm_buf_append_u16(sized, options->policydigest_len);
 	if (options->policydigest_len)
-		tpm_buf_append(&sized, options->policydigest, options->policydigest_len);
+		tpm_buf_append(sized, options->policydigest, options->policydigest_len);
 
 	/* public parameters */
-	tpm_buf_append_u16(&sized, TPM_ALG_NULL);
-	tpm_buf_append_u16(&sized, 0);
+	tpm_buf_append_u16(sized, TPM_ALG_NULL);
+	tpm_buf_append_u16(sized, 0);
 
-	tpm_buf_append(&buf, sized.data, sized.length);
+	tpm_buf_append(buf, sized->data, sized->length);
 
 	/* outside info */
-	tpm_buf_append_u16(&buf, 0);
+	tpm_buf_append_u16(buf, 0);
 
 	/* creation PCR */
-	tpm_buf_append_u32(&buf, 0);
+	tpm_buf_append_u32(buf, 0);
 
-	if (buf.flags & TPM_BUF_OVERFLOW) {
+	if (buf->flags & TPM_BUF_OVERFLOW) {
 		rc = -E2BIG;
 		tpm2_end_auth_session(chip);
 		goto out;
 	}
 
-	tpm_buf_fill_hmac_session(chip, &buf);
-	rc = tpm_transmit_cmd(chip, &buf, 4, "sealing data");
-	rc = tpm_buf_check_hmac_response(chip, &buf, rc);
+	tpm_buf_fill_hmac_session(chip, buf);
+	rc = tpm_transmit_cmd(chip, buf, 4, "sealing data");
+	rc = tpm_buf_check_hmac_response(chip, buf, rc);
 	if (rc)
 		goto out;
 
-	blob_len = tpm_buf_read_u32(&buf, &offset);
-	if (blob_len > MAX_BLOB_SIZE || buf.flags & TPM_BUF_BOUNDARY_ERROR) {
+	blob_len = tpm_buf_read_u32(buf, &offset);
+	if (blob_len > MAX_BLOB_SIZE || buf->flags & TPM_BUF_BOUNDARY_ERROR) {
 		rc = -E2BIG;
 		goto out;
 	}
-	if (buf.length - offset < blob_len) {
+	if (buf->length - offset < blob_len) {
 		rc = -EFAULT;
 		goto out;
 	}
 
-	blob_len = tpm2_key_encode(payload, options, &buf.data[offset], blob_len);
+	blob_len = tpm2_key_encode(payload, options, &buf->data[offset],
+				   blob_len);
 
 out:
-	tpm_buf_destroy(&sized);
-	tpm_buf_destroy(&buf);
-
 	if (rc > 0) {
 		if (tpm2_rc_value(rc) == TPM2_RC_HASH)
 			rc = -EINVAL;
@@ -387,7 +381,6 @@ static int tpm2_load_cmd(struct tpm_chip *chip,
 			 struct trusted_key_options *options,
 			 u32 *blob_handle)
 {
-	struct tpm_buf buf;
 	unsigned int private_len;
 	unsigned int public_len;
 	unsigned int blob_len;
@@ -395,6 +388,10 @@ static int tpm2_load_cmd(struct tpm_chip *chip,
 	int rc;
 	u32 attrs;
 
+	struct tpm_buf *buf __free(kfree) = kzalloc(PAGE_SIZE, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
 	rc = tpm2_key_decode(payload, options, &blob);
 	if (rc) {
 		/* old form */
@@ -438,35 +435,29 @@ static int tpm2_load_cmd(struct tpm_chip *chip,
 	if (rc)
 		return rc;
 
-	rc = tpm_buf_init(&buf, TPM2_ST_SESSIONS, TPM2_CC_LOAD);
-	if (rc) {
-		tpm2_end_auth_session(chip);
-		return rc;
-	}
-
-	tpm_buf_append_name(chip, &buf, options->keyhandle, NULL);
-	tpm_buf_append_hmac_session(chip, &buf, 0, options->keyauth,
+	tpm_buf_reset(buf, PAGE_SIZE, TPM2_ST_SESSIONS, TPM2_CC_LOAD);
+	tpm_buf_append_name(chip, buf, options->keyhandle, NULL);
+	tpm_buf_append_hmac_session(chip, buf, 0, options->keyauth,
 				    TPM_DIGEST_SIZE);
 
-	tpm_buf_append(&buf, blob, blob_len);
+	tpm_buf_append(buf, blob, blob_len);
 
-	if (buf.flags & TPM_BUF_OVERFLOW) {
+	if (buf->flags & TPM_BUF_OVERFLOW) {
 		rc = -E2BIG;
 		tpm2_end_auth_session(chip);
 		goto out;
 	}
 
-	tpm_buf_fill_hmac_session(chip, &buf);
-	rc = tpm_transmit_cmd(chip, &buf, 4, "loading blob");
-	rc = tpm_buf_check_hmac_response(chip, &buf, rc);
+	tpm_buf_fill_hmac_session(chip, buf);
+	rc = tpm_transmit_cmd(chip, buf, 4, "loading blob");
+	rc = tpm_buf_check_hmac_response(chip, buf, rc);
 	if (!rc)
 		*blob_handle = be32_to_cpup(
-			(__be32 *) &buf.data[TPM_HEADER_SIZE]);
+			(__be32 *)&buf->data[TPM_HEADER_SIZE]);
 
 out:
 	if (blob != payload->blob)
 		kfree(blob);
-	tpm_buf_destroy(&buf);
 
 	if (rc > 0)
 		rc = -EPERM;
@@ -491,25 +482,23 @@ static int tpm2_unseal_cmd(struct tpm_chip *chip,
 			   struct trusted_key_options *options,
 			   u32 blob_handle)
 {
-	struct tpm_buf buf;
 	u16 data_len;
 	u8 *data;
 	int rc;
 
+	struct tpm_buf *buf __free(kfree) = kzalloc(PAGE_SIZE, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
 	rc = tpm2_start_auth_session(chip);
 	if (rc)
 		return rc;
 
-	rc = tpm_buf_init(&buf, TPM2_ST_SESSIONS, TPM2_CC_UNSEAL);
-	if (rc) {
-		tpm2_end_auth_session(chip);
-		return rc;
-	}
-
-	tpm_buf_append_name(chip, &buf, blob_handle, NULL);
+	tpm_buf_reset(buf, PAGE_SIZE, TPM2_ST_SESSIONS, TPM2_CC_UNSEAL);
+	tpm_buf_append_name(chip, buf, blob_handle, NULL);
 
 	if (!options->policyhandle) {
-		tpm_buf_append_hmac_session(chip, &buf, TPM2_SA_ENCRYPT,
+		tpm_buf_append_hmac_session(chip, buf, TPM2_SA_ENCRYPT,
 					    options->blobauth,
 					    options->blobauth_len);
 	} else {
@@ -524,32 +513,28 @@ static int tpm2_unseal_cmd(struct tpm_chip *chip,
 		 * could repeat our actions with the exfiltrated
 		 * password.
 		 */
-		tpm2_buf_append_auth(&buf, options->policyhandle,
+		tpm2_buf_append_auth(buf, options->policyhandle,
 				     NULL /* nonce */, 0, 0,
 				     options->blobauth, options->blobauth_len);
-		tpm_buf_append_hmac_session_opt(chip, &buf, TPM2_SA_ENCRYPT,
+		tpm_buf_append_hmac_session_opt(chip, buf, TPM2_SA_ENCRYPT,
 						NULL, 0);
 	}
 
-	tpm_buf_fill_hmac_session(chip, &buf);
-	rc = tpm_transmit_cmd(chip, &buf, 6, "unsealing");
-	rc = tpm_buf_check_hmac_response(chip, &buf, rc);
+	tpm_buf_fill_hmac_session(chip, buf);
+	rc = tpm_transmit_cmd(chip, buf, 6, "unsealing");
+	rc = tpm_buf_check_hmac_response(chip, buf, rc);
 	if (rc > 0)
 		rc = -EPERM;
 
 	if (!rc) {
 		data_len = be16_to_cpup(
-			(__be16 *) &buf.data[TPM_HEADER_SIZE + 4]);
-		if (data_len < MIN_KEY_SIZE ||  data_len > MAX_KEY_SIZE) {
-			rc = -EFAULT;
-			goto out;
-		}
+			(__be16 *)&buf->data[TPM_HEADER_SIZE + 4]);
+		if (data_len < MIN_KEY_SIZE ||  data_len > MAX_KEY_SIZE)
+			return -EFAULT;
 
-		if (tpm_buf_length(&buf) < TPM_HEADER_SIZE + 6 + data_len) {
-			rc = -EFAULT;
-			goto out;
-		}
-		data = &buf.data[TPM_HEADER_SIZE + 6];
+		if (tpm_buf_length(buf) < TPM_HEADER_SIZE + 6 + data_len)
+			return -EFAULT;
+		data = &buf->data[TPM_HEADER_SIZE + 6];
 
 		if (payload->old_format) {
 			/* migratable flag is at the end of the key */
@@ -566,8 +551,6 @@ static int tpm2_unseal_cmd(struct tpm_chip *chip,
 		}
 	}
 
-out:
-	tpm_buf_destroy(&buf);
 	return rc;
 }
 
-- 
2.39.5


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