From: Jarkko Sakkinen <[email protected]>

Decouple kzalloc from buffer creation, so that a managed allocation can be
used:

        struct tpm_buf *buf __free(kfree) buf = kzalloc(TPM_BUFSIZE,
                                                        GFP_KERNEL);
        if (!buf)
                return -ENOMEM;

        tpm_buf_init(buf, TPM_BUFSIZE);

Alternatively, stack allocations are also possible:

        u8 buf_data[512];
        struct tpm_buf *buf = (struct tpm_buf *)buf_data;
        tpm_buf_init(buf, sizeof(buf_data));

This is achieved by embedding buffer's header inside the allocated blob,
instead of having an outer wrapper.

Cc: Ross Philipson <[email protected]>
Signed-off-by: Jarkko Sakkinen <[email protected]>
Reviewed-by: Stefan Berger <[email protected]>
---
 drivers/char/tpm/tpm-buf.c                | 123 ++++++----
 drivers/char/tpm/tpm-interface.c          |  66 +++---
 drivers/char/tpm/tpm-sysfs.c              |  21 +-
 drivers/char/tpm/tpm.h                    |   1 -
 drivers/char/tpm/tpm1-cmd.c               | 129 +++++------
 drivers/char/tpm/tpm2-cmd.c               | 266 ++++++++++------------
 drivers/char/tpm/tpm2-sessions.c          | 142 ++++++------
 drivers/char/tpm/tpm2-space.c             |  44 ++--
 drivers/char/tpm/tpm_vtpm_proxy.c         |  30 ++-
 include/linux/tpm.h                       |  20 +-
 security/keys/trusted-keys/trusted_tpm1.c |  36 +--
 security/keys/trusted-keys/trusted_tpm2.c | 173 +++++++-------
 12 files changed, 499 insertions(+), 552 deletions(-)

diff --git a/drivers/char/tpm/tpm-buf.c b/drivers/char/tpm/tpm-buf.c
index 11b6bcf2f43d..042da92f94e1 100644
--- a/drivers/char/tpm/tpm-buf.c
+++ b/drivers/char/tpm/tpm-buf.c
@@ -7,81 +7,107 @@
 #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)
+static void __tpm_buf_size_invariant(struct tpm_buf *buf, u16 buf_size)
 {
-       buf->data = (u8 *)__get_free_page(GFP_KERNEL);
-       if (!buf->data)
-               return -ENOMEM;
-
-       tpm_buf_reset(buf, tag, ordinal);
-       return 0;
+       u32 buf_size_2 = (u32)buf->capacity + (u32)sizeof(*buf);
+
+       if (!buf->capacity) {
+               if (buf_size > TPM_BUFSIZE) {
+                       WARN(1, "%s: size overflow: %u\n", __func__, buf_size);
+                       buf->flags |= TPM_BUF_INVALID;
+               }
+       } else {
+               if (buf_size != buf_size_2) {
+                       WARN(1, "%s: size mismatch: %u != %u\n", __func__, 
buf_size,
+                            buf_size_2);
+                       buf->flags |= TPM_BUF_INVALID;
+               }
+       }
 }
-EXPORT_SYMBOL_GPL(tpm_buf_init);
 
-/**
- * tpm_buf_reset() - 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
- */
-void tpm_buf_reset(struct tpm_buf *buf, u16 tag, u32 ordinal)
+static void __tpm_buf_reset(struct tpm_buf *buf, u16 buf_size, u16 tag, u32 
ordinal)
 {
        struct tpm_header *head = (struct tpm_header *)buf->data;
 
+       __tpm_buf_size_invariant(buf, buf_size);
+
+       if (buf->flags & TPM_BUF_INVALID)
+               return;
+
        WARN_ON(tag != TPM_TAG_RQU_COMMAND && tag != TPM2_ST_NO_SESSIONS &&
                tag != TPM2_ST_SESSIONS && tag != 0);
 
        buf->flags = 0;
        buf->length = sizeof(*head);
+       buf->capacity = buf_size - sizeof(*buf);
        head->tag = cpu_to_be16(tag);
        head->length = cpu_to_be32(sizeof(*head));
        head->ordinal = cpu_to_be32(ordinal);
 }
-EXPORT_SYMBOL_GPL(tpm_buf_reset);
+
+static void __tpm_buf_reset_sized(struct tpm_buf *buf, u16 buf_size)
+{
+       __tpm_buf_size_invariant(buf, buf_size);
+
+       if (buf->flags & TPM_BUF_INVALID)
+               return;
+
+       buf->flags = TPM_BUF_TPM2B;
+       buf->length = 2;
+       buf->capacity = buf_size - sizeof(*buf);
+       buf->data[0] = 0;
+       buf->data[1] = 0;
+}
 
 /**
- * tpm_buf_init_sized() - Allocate and initialize a sized (TPM2B) buffer
- * @buf:       A @tpm_buf
- *
- * Return: 0 or -ENOMEM
+ * tpm_buf_init() - Initialize a TPM command
+ * @buf:       A &tpm_buf
+ * @buf_size:  Size of the buffer.
  */
-int tpm_buf_init_sized(struct tpm_buf *buf)
+void tpm_buf_init(struct tpm_buf *buf, u16 buf_size)
 {
-       buf->data = (u8 *)__get_free_page(GFP_KERNEL);
-       if (!buf->data)
-               return -ENOMEM;
+       memset(buf, 0, buf_size);
+       __tpm_buf_reset(buf, buf_size, TPM_TAG_RQU_COMMAND, 0);
+}
+EXPORT_SYMBOL_GPL(tpm_buf_init);
 
-       tpm_buf_reset_sized(buf);
-       return 0;
+/**
+ * tpm_buf_init_sized() - Initialize a sized buffer
+ * @buf:       A &tpm_buf
+ * @buf_size:  Size of the buffer.
+ */
+void tpm_buf_init_sized(struct tpm_buf *buf, u16 buf_size)
+{
+       memset(buf, 0, buf_size);
+       __tpm_buf_reset_sized(buf, buf_size);
 }
 EXPORT_SYMBOL_GPL(tpm_buf_init_sized);
 
 /**
- * tpm_buf_reset_sized() - Initialize a sized buffer
+ * tpm_buf_reset() - Re-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
  */
-void tpm_buf_reset_sized(struct tpm_buf *buf)
+void tpm_buf_reset(struct tpm_buf *buf, u16 tag, u32 ordinal)
 {
-       buf->flags = TPM_BUF_TPM2B;
-       buf->length = 2;
-       buf->data[0] = 0;
-       buf->data[1] = 0;
+       u16 buf_size = buf->capacity + sizeof(*buf);
+
+       __tpm_buf_reset(buf, buf_size, tag, ordinal);
 }
-EXPORT_SYMBOL_GPL(tpm_buf_reset_sized);
+EXPORT_SYMBOL_GPL(tpm_buf_reset);
 
-void tpm_buf_destroy(struct tpm_buf *buf)
+/**
+ * tpm_buf_reset_sized() - Re-initialize a sized buffer
+ * @buf:       A &tpm_buf
+ */
+void tpm_buf_reset_sized(struct tpm_buf *buf)
 {
-       free_page((unsigned long)buf->data);
+       u16 buf_size = buf->capacity + sizeof(*buf);
+
+       __tpm_buf_reset_sized(buf, buf_size);
 }
-EXPORT_SYMBOL_GPL(tpm_buf_destroy);
+EXPORT_SYMBOL_GPL(tpm_buf_reset_sized);
 
 /**
  * tpm_buf_length() - Return the number of bytes consumed by the data
@@ -89,8 +115,11 @@ EXPORT_SYMBOL_GPL(tpm_buf_destroy);
  *
  * Return: The number of bytes consumed by the buffer
  */
-u32 tpm_buf_length(struct tpm_buf *buf)
+u16 tpm_buf_length(struct tpm_buf *buf)
 {
+       if (buf->flags & TPM_BUF_INVALID)
+               return 0;
+
        return buf->length;
 }
 EXPORT_SYMBOL_GPL(tpm_buf_length);
@@ -103,10 +132,12 @@ EXPORT_SYMBOL_GPL(tpm_buf_length);
  */
 void tpm_buf_append(struct tpm_buf *buf, const u8 *new_data, u16 new_length)
 {
+       u32 total_length = (u32)buf->length + (u32)new_length;
+
        if (buf->flags & TPM_BUF_INVALID)
                return;
 
-       if ((buf->length + new_length) > PAGE_SIZE) {
+       if (total_length > (u32)buf->capacity) {
                WARN(1, "tpm_buf: write overflow\n");
                buf->flags |= TPM_BUF_INVALID;
                return;
diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c
index 677dcef05dfb..0810e58aca7a 100644
--- a/drivers/char/tpm/tpm-interface.c
+++ b/drivers/char/tpm/tpm-interface.c
@@ -494,46 +494,38 @@ struct tpm1_get_random_out {
 static int tpm1_get_random(struct tpm_chip *chip, u8 *out, size_t max)
 {
        struct tpm1_get_random_out *resp;
-       struct tpm_buf buf;
        u32 recd;
        int rc;
 
        if (!out || !max || max > TPM_MAX_RNG_DATA)
                return -EINVAL;
 
-       rc = tpm_buf_init(&buf, TPM_TAG_RQU_COMMAND, TPM_ORD_GETRANDOM);
-       if (rc)
-               return rc;
+       struct tpm_buf *buf __free(kfree) = kzalloc(TPM_BUFSIZE, GFP_KERNEL);
+       if (!buf)
+               return -ENOMEM;
 
-       tpm_buf_append_u32(&buf, max);
+       tpm_buf_init(buf, TPM_BUFSIZE);
+       tpm_buf_reset(buf, TPM_TAG_RQU_COMMAND, TPM_ORD_GETRANDOM);
+       tpm_buf_append_u32(buf, max);
 
-       rc = tpm_transmit_cmd(chip, &buf, sizeof(resp->rng_data_len), 
"TPM_GetRandom");
+       rc = tpm_transmit_cmd(chip, buf, sizeof(resp->rng_data_len), 
"TPM_GetRandom");
        if (rc) {
                if (rc > 0)
                        rc = -EIO;
-               goto err;
+               return rc;
        }
 
-       resp = (struct tpm1_get_random_out *)&buf.data[TPM_HEADER_SIZE];
+       resp = (struct tpm1_get_random_out *)&buf->data[TPM_HEADER_SIZE];
 
        recd = be32_to_cpu(resp->rng_data_len);
-       if (recd > max) {
-               rc = -EIO;
-               goto err;
-       }
+       if (recd > max)
+               return -EIO;
 
-       if (buf.length < TPM_HEADER_SIZE + sizeof(resp->rng_data_len) + recd) {
-               rc = -EIO;
-               goto err;
-       }
+       if (buf->length < TPM_HEADER_SIZE + sizeof(resp->rng_data_len) + recd)
+               return -EIO;
 
        memcpy(out, resp->rng_data, recd);
-       tpm_buf_destroy(&buf);
        return recd;
-
-err:
-       tpm_buf_destroy(&buf);
-       return rc;
 }
 
 struct tpm2_get_random_out {
@@ -545,7 +537,6 @@ static int tpm2_get_random(struct tpm_chip *chip, u8 *out, 
size_t max)
 {
        struct tpm2_get_random_out *resp;
        struct tpm_header *head;
-       struct tpm_buf buf;
        off_t offset;
        u32 recd;
        int ret;
@@ -553,30 +544,30 @@ static int tpm2_get_random(struct tpm_chip *chip, u8 
*out, size_t max)
        if (!out || !max || max > TPM_MAX_RNG_DATA)
                return -EINVAL;
 
-       ret = tpm_buf_init(&buf, TPM2_ST_SESSIONS, TPM2_CC_GET_RANDOM);
-       if (ret)
-               return ret;
+       struct tpm_buf *buf __free(kfree) = kzalloc(TPM_BUFSIZE, GFP_KERNEL);
+       if (!buf)
+               return -ENOMEM;
 
+       tpm_buf_init(buf, TPM_BUFSIZE);
+       tpm_buf_reset(buf, TPM2_ST_SESSIONS, TPM2_CC_GET_RANDOM);
        if (tpm2_chip_auth(chip)) {
-               tpm_buf_append_hmac_session(chip, &buf,
+               tpm_buf_append_hmac_session(chip, buf,
                                            TPM2_SA_ENCRYPT | 
TPM2_SA_CONTINUE_SESSION,
                                            NULL, 0);
        } else  {
-               head = (struct tpm_header *)buf.data;
+               head = (struct tpm_header *)buf->data;
                head->tag = cpu_to_be16(TPM2_ST_NO_SESSIONS);
        }
-       tpm_buf_append_u16(&buf, max);
+       tpm_buf_append_u16(buf, max);
 
-       ret = tpm_buf_fill_hmac_session(chip, &buf);
-       if (ret) {
-               tpm_buf_destroy(&buf);
+       ret = tpm_buf_fill_hmac_session(chip, buf);
+       if (ret)
                return ret;
-       }
 
-       ret = tpm_transmit_cmd(chip, &buf, offsetof(struct tpm2_get_random_out, 
buffer),
+       ret = tpm_transmit_cmd(chip, buf, offsetof(struct tpm2_get_random_out, 
buffer),
                               "TPM2_GetRandom");
 
-       ret = tpm_buf_check_hmac_response(chip, &buf, ret);
+       ret = tpm_buf_check_hmac_response(chip, buf, ret);
        if (ret) {
                if (ret > 0)
                        ret = -EIO;
@@ -584,17 +575,17 @@ static int tpm2_get_random(struct tpm_chip *chip, u8 
*out, size_t max)
                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;
 
-       resp = (struct tpm2_get_random_out *)&buf.data[offset];
+       resp = (struct tpm2_get_random_out *)&buf->data[offset];
        recd = min_t(u32, be16_to_cpu(resp->size), max);
 
-       if (tpm_buf_length(&buf) <
+       if (tpm_buf_length(buf) <
            TPM_HEADER_SIZE + offsetof(struct tpm2_get_random_out, buffer) + 
recd) {
                ret = -EIO;
                goto out;
@@ -605,7 +596,6 @@ static int tpm2_get_random(struct tpm_chip *chip, u8 *out, 
size_t max)
 
 out:
        tpm2_end_auth_session(chip);
-       tpm_buf_destroy(&buf);
        return ret;
 }
 
diff --git a/drivers/char/tpm/tpm-sysfs.c b/drivers/char/tpm/tpm-sysfs.c
index 4a6a27ee295d..0f321c307bc6 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(TPM_BUFSIZE, 
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_init(tpm_buf, TPM_BUFSIZE);
+       tpm_buf_reset(tpm_buf, 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,
-                            "attempting to read the PUBEK"))
-               goto out_buf;
+       if (tpm_transmit_cmd(chip, tpm_buf, READ_PUBEK_RESULT_MIN_BODY_SIZE, 
"TPM_ReadPubek"))
+               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/tpm.h b/drivers/char/tpm/tpm.h
index f698d01401de..c4bbd8f04605 100644
--- a/drivers/char/tpm/tpm.h
+++ b/drivers/char/tpm/tpm.h
@@ -32,7 +32,6 @@
 #endif
 
 #define TPM_MINOR              224     /* officially assigned */
-#define TPM_BUFSIZE            4096
 #define TPM_NUM_DEVICES                65536
 #define TPM_RETRY              50
 
diff --git a/drivers/char/tpm/tpm1-cmd.c b/drivers/char/tpm/tpm1-cmd.c
index 0604e11c9778..d8f16e66666b 100644
--- a/drivers/char/tpm/tpm1-cmd.c
+++ b/drivers/char/tpm/tpm1-cmd.c
@@ -323,20 +323,14 @@ 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");
-
-       rc = tpm_buf_init(&buf, TPM_TAG_RQU_COMMAND, TPM_ORD_STARTUP);
-       if (rc < 0)
-               return rc;
-
-       tpm_buf_append_u16(&buf, TPM_ST_CLEAR);
-
-       rc = tpm_transmit_cmd(chip, &buf, 0, "attempting to start the TPM");
-       tpm_buf_destroy(&buf);
-       return rc;
+       struct tpm_buf *buf __free(kfree) = kzalloc(TPM_BUFSIZE, GFP_KERNEL);
+       if (!buf)
+               return -ENOMEM;
+
+       tpm_buf_init(buf, TPM_BUFSIZE);
+       tpm_buf_reset(buf, TPM_TAG_RQU_COMMAND, TPM_ORD_STARTUP);
+       tpm_buf_append_u16(buf, TPM_ST_CLEAR);
+       return tpm_transmit_cmd(chip, buf, 0, "TPM_Startup");
 }
 
 int tpm1_get_timeouts(struct tpm_chip *chip)
@@ -463,50 +457,47 @@ 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;
-
-       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);
-       return rc;
+       struct tpm_buf *buf __free(kfree) = kzalloc(TPM_BUFSIZE, GFP_KERNEL);
+       if (!buf)
+               return -ENOMEM;
+
+       tpm_buf_init(buf, TPM_BUFSIZE);
+       tpm_buf_reset(buf, TPM_TAG_RQU_COMMAND, TPM_ORD_PCR_EXTEND);
+       tpm_buf_append_u32(buf, pcr_idx);
+       tpm_buf_append(buf, hash, TPM_DIGEST_SIZE);
+       return tpm_transmit_cmd(chip, buf, TPM_DIGEST_SIZE, log_msg);
 }
 
 #define TPM_ORD_GET_CAP 101
 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(TPM_BUFSIZE, GFP_KERNEL);
+       if (!buf)
+               return -ENOMEM;
+
+       tpm_buf_init(buf, TPM_BUFSIZE);
+       tpm_buf_reset(buf, 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);
@@ -514,29 +505,24 @@ EXPORT_SYMBOL_GPL(tpm1_getcap);
 #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(TPM_BUFSIZE, GFP_KERNEL);
+       if (!buf)
+               return -ENOMEM;
 
-       tpm_buf_append_u32(&buf, pcr_idx);
+       tpm_buf_init(buf, TPM_BUFSIZE);
+       tpm_buf_reset(buf, TPM_TAG_RQU_COMMAND, TPM_ORD_PCRREAD);
+       tpm_buf_append_u32(buf, pcr_idx);
 
-       rc = tpm_transmit_cmd(chip, &buf, TPM_DIGEST_SIZE,
-                             "attempting to read a pcr value");
+       rc = tpm_transmit_cmd(chip, buf, TPM_DIGEST_SIZE, "TPM_PCRRead");
        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;
 }
 
@@ -550,16 +536,13 @@ 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;
+       struct tpm_buf *buf __free(kfree) = kzalloc(TPM_BUFSIZE, GFP_KERNEL);
+       if (!buf)
+               return -ENOMEM;
 
-       rc = tpm_buf_init(&buf, TPM_TAG_RQU_COMMAND, TPM_ORD_CONTINUE_SELFTEST);
-       if (rc)
-               return rc;
-
-       rc = tpm_transmit_cmd(chip, &buf, 0, "continue selftest");
-       tpm_buf_destroy(&buf);
-       return rc;
+       tpm_buf_init(buf, TPM_BUFSIZE);
+       tpm_buf_reset(buf, TPM_TAG_RQU_COMMAND, TPM_ORD_CONTINUE_SELFTEST);
+       return tpm_transmit_cmd(chip, buf, 0, "TPM_ContinueSelfTest");
 }
 
 /**
@@ -673,22 +656,24 @@ 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(TPM_BUFSIZE, 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_init(buf, TPM_BUFSIZE);
+       tpm_buf_reset(buf, 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
@@ -703,7 +688,7 @@ 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, TPM_TAG_RQU_COMMAND, TPM_ORD_SAVESTATE);
        }
 
        if (rc)
@@ -713,8 +698,6 @@ 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 8ba6cd6819f1..f066efb54a2c 100644
--- a/drivers/char/tpm/tpm2-cmd.c
+++ b/drivers/char/tpm/tpm2-cmd.c
@@ -119,12 +119,15 @@ 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(TPM_BUFSIZE, GFP_KERNEL);
+       if (!buf)
+               return -ENOMEM;
+
        if (pcr_idx >= TPM2_PLATFORM_PCR)
                return -EINVAL;
 
@@ -139,36 +142,31 @@ 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_init(buf, TPM_BUFSIZE);
+       tpm_buf_reset(buf, 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, "TPM2_PCR_Read");
        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;
 }
 
@@ -184,57 +182,53 @@ 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(TPM_BUFSIZE, 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_init(buf, TPM_BUFSIZE);
+       tpm_buf_reset(buf, TPM2_ST_SESSIONS, TPM2_CC_PCR_EXTEND);
 
        if (!disable_pcr_integrity) {
-               rc = tpm_buf_append_name(chip, &buf, pcr_idx, (u8 *)&pcr_idx,
+               rc = tpm_buf_append_name(chip, buf, pcr_idx, (u8 *)&pcr_idx,
                                         sizeof(u32));
-               if (rc) {
-                       tpm_buf_destroy(&buf);
+               if (rc)
                        return rc;
-               }
-               tpm_buf_append_hmac_session(chip, &buf, 0, NULL, 0);
+               tpm_buf_append_hmac_session(chip, buf, 0, NULL, 0);
        } else {
-               tpm_buf_append_u32(&buf, pcr_idx);
-               tpm_buf_append_auth(chip, &buf, NULL, 0);
+               tpm_buf_append_u32(buf, pcr_idx);
+               tpm_buf_append_auth(chip, buf, 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 (buf->flags & TPM_BUF_INVALID)
+               return -EINVAL;
 
        if (!disable_pcr_integrity) {
-               rc = tpm_buf_fill_hmac_session(chip, &buf);
-               if (rc) {
-                       tpm_buf_destroy(&buf);
+               rc = tpm_buf_fill_hmac_session(chip, buf);
+               if (rc)
                        return rc;
-               }
        }
 
-       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);
+       rc = tpm_transmit_cmd(chip, buf, 0, "TPM2_PCR_Extend");
 
-       tpm_buf_destroy(&buf);
+       if (!disable_pcr_integrity)
+               rc = tpm_buf_check_hmac_response(chip, buf, rc);
 
        return rc;
 }
@@ -246,20 +240,18 @@ int tpm2_pcr_extend(struct tpm_chip *chip, u32 pcr_idx,
  */
 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(TPM_BUFSIZE, 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_init(buf, TPM_BUFSIZE);
+       tpm_buf_reset(buf, 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, "TPM2_FlushContext");
 }
 EXPORT_SYMBOL_GPL(tpm2_flush_context);
 
@@ -286,19 +278,20 @@ 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(TPM_BUFSIZE, GFP_KERNEL);
+       if (!buf)
+               return -ENOMEM;
+
+       tpm_buf_init(buf, TPM_BUFSIZE);
+       tpm_buf_reset(buf, 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];
+               out = (struct tpm2_get_cap_out *)&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
@@ -310,7 +303,6 @@ 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);
@@ -327,15 +319,14 @@ 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(TPM_BUFSIZE, 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_init(buf, TPM_BUFSIZE);
+       tpm_buf_reset(buf, TPM2_ST_NO_SESSIONS, TPM2_CC_SHUTDOWN);
+       tpm_buf_append_u16(buf, shutdown_type);
+       tpm_transmit_cmd(chip, buf, 0, "TPM2_Shutdown");
 }
 
 /**
@@ -353,20 +344,19 @@ 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;
-
-               tpm_buf_append_u8(&buf, full);
-               rc = tpm_transmit_cmd(chip, &buf, 0,
-                                     "attempting the self test");
-               tpm_buf_destroy(&buf);
+       struct tpm_buf *buf __free(kfree) = kzalloc(TPM_BUFSIZE, GFP_KERNEL);
+       if (!buf)
+               return -ENOMEM;
 
+       tpm_buf_init(buf, TPM_BUFSIZE);
+       tpm_buf_reset(buf, TPM2_ST_NO_SESSIONS, TPM2_CC_SELF_TEST);
+       for (full = 0; full < 2; full++) {
+               tpm_buf_reset(buf, TPM2_ST_NO_SESSIONS, TPM2_CC_SELF_TEST);
+               tpm_buf_append_u8(buf, full);
+               rc = tpm_transmit_cmd(chip, buf, 0, "TPM2_SelfTest");
                if (rc == TPM2_RC_TESTING)
                        rc = TPM2_RC_SUCCESS;
                if (rc == TPM2_RC_INITIALIZE || rc == TPM2_RC_SUCCESS)
@@ -391,23 +381,24 @@ 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(TPM_BUFSIZE, GFP_KERNEL);
+       if (!buf)
+               return -ENOMEM;
+
+       tpm_buf_init(buf, TPM_BUFSIZE);
+       tpm_buf_reset(buf, 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);
@@ -447,7 +438,6 @@ 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;
@@ -459,39 +449,37 @@ 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(TPM_BUFSIZE, 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_init(buf, TPM_BUFSIZE);
+       tpm_buf_reset(buf, 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, "TPM2_GetCapability(PCRS)");
        if (rc)
-               goto out;
+               return rc;
 
-       nr_possible_banks = be32_to_cpup(
-               (__be32 *)&buf.data[TPM_HEADER_SIZE + 5]);
+       nr_possible_banks = be32_to_cpup((__be32 *)&buf->data[TPM_HEADER_SIZE + 
5]);
        if (nr_possible_banks > TPM2_MAX_PCR_BANKS) {
                pr_err("tpm: out of bank capacity: %u > %u\n",
                       nr_possible_banks, TPM2_MAX_PCR_BANKS);
-               rc = -ENOMEM;
-               goto out;
+               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);
@@ -503,7 +491,7 @@ 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++;
                }
@@ -515,21 +503,21 @@ 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(TPM_BUFSIZE, GFP_KERNEL);
+       if (!buf)
+               return -ENOMEM;
+
        rc = tpm2_get_tpm_pt(chip, TPM_PT_TOTAL_COMMANDS, &nr_commands, NULL);
        if (rc)
                goto out;
@@ -546,30 +534,24 @@ 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_init(buf, TPM_BUFSIZE);
+       tpm_buf_reset(buf, 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])) {
+       if (nr_commands != 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;
@@ -581,8 +563,6 @@ int tpm2_get_cc_attrs_tbl(struct tpm_chip *chip)
                }
        }
 
-       tpm_buf_destroy(&buf);
-
 out:
        if (rc > 0)
                rc = -ENODEV;
@@ -603,20 +583,14 @@ EXPORT_SYMBOL_GPL(tpm2_get_cc_attrs_tbl);
 
 static int tpm2_startup(struct tpm_chip *chip)
 {
-       struct tpm_buf buf;
-       int rc;
-
-       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);
-
-       return rc;
+       struct tpm_buf *buf __free(kfree) = kzalloc(TPM_BUFSIZE, GFP_KERNEL);
+       if (!buf)
+               return -ENOMEM;
+
+       tpm_buf_init(buf, TPM_BUFSIZE);
+       tpm_buf_reset(buf, TPM2_ST_NO_SESSIONS, TPM2_CC_STARTUP);
+       tpm_buf_append_u16(buf, TPM2_SU_CLEAR);
+       return tpm_transmit_cmd(chip, buf, 0, "TPM2_Startup");
 }
 
 /**
diff --git a/drivers/char/tpm/tpm2-sessions.c b/drivers/char/tpm/tpm2-sessions.c
index 016bed63a755..0926da478932 100644
--- a/drivers/char/tpm/tpm2-sessions.c
+++ b/drivers/char/tpm/tpm2-sessions.c
@@ -175,7 +175,6 @@ int tpm2_read_public(struct tpm_chip *chip, u32 handle, 
void *name)
        u32 mso = tpm2_handle_mso(handle);
        off_t offset = TPM_HEADER_SIZE;
        int rc, name_size_alg;
-       struct tpm_buf buf;
 
        if (mso != TPM2_MSO_PERSISTENT && mso != TPM2_MSO_VOLATILE &&
            mso != TPM2_MSO_NVRAM) {
@@ -183,47 +182,41 @@ int tpm2_read_public(struct tpm_chip *chip, u32 handle, 
void *name)
                return sizeof(u32);
        }
 
-       rc = tpm_buf_init(&buf, TPM2_ST_NO_SESSIONS, TPM2_CC_READ_PUBLIC);
-       if (rc)
-               return rc;
+       struct tpm_buf *buf __free(kfree) = kzalloc(TPM_BUFSIZE, GFP_KERNEL);
+       if (!buf)
+               return -ENOMEM;
 
-       tpm_buf_append_u32(&buf, handle);
+       tpm_buf_init(buf, TPM_BUFSIZE);
+       tpm_buf_reset(buf, TPM2_ST_NO_SESSIONS, TPM2_CC_READ_PUBLIC);
+       tpm_buf_append_u32(buf, handle);
 
-       rc = tpm_transmit_cmd(chip, &buf, 0, "TPM2_ReadPublic");
-       if (rc) {
-               tpm_buf_destroy(&buf);
+       rc = tpm_transmit_cmd(chip, buf, 0, "TPM2_ReadPublic");
+       if (rc)
                return tpm_ret_to_err(rc);
-       }
 
        /* Skip TPMT_PUBLIC: */
-       offset += tpm_buf_read_u16(&buf, &offset);
+       offset += tpm_buf_read_u16(buf, &offset);
 
        /*
         * Ensure space for the length field of TPM2B_NAME and hashAlg field of
         * TPMT_HA (the extra four bytes).
         */
-       if (offset + 4 > tpm_buf_length(&buf)) {
-               tpm_buf_destroy(&buf);
+       if (offset + 4 > tpm_buf_length(buf))
                return -EIO;
-       }
 
-       rc = tpm_buf_read_u16(&buf, &offset);
-       name_size_alg = name_size(&buf.data[offset]);
+       rc = tpm_buf_read_u16(buf, &offset);
+       name_size_alg = name_size(&buf->data[offset]);
 
        if (name_size_alg < 0)
                return name_size_alg;
 
-       if (rc != name_size_alg) {
-               tpm_buf_destroy(&buf);
+       if (rc != name_size_alg)
                return -EIO;
-       }
 
-       if (offset + rc > tpm_buf_length(&buf)) {
-               tpm_buf_destroy(&buf);
+       if (offset + rc > tpm_buf_length(buf))
                return -EIO;
-       }
 
-       memcpy(name, &buf.data[offset], rc);
+       memcpy(name, &buf->data[offset], rc);
        return name_size_alg;
 }
 EXPORT_SYMBOL_GPL(tpm2_read_public);
@@ -929,7 +922,6 @@ 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;
 
@@ -938,6 +930,10 @@ int tpm2_start_auth_session(struct tpm_chip *chip)
                return 0;
        }
 
+       struct tpm_buf *buf __free(kfree) = kzalloc(TPM_BUFSIZE, GFP_KERNEL);
+       if (!buf)
+               return -ENOMEM;
+
        auth = kzalloc(sizeof(*auth), GFP_KERNEL);
        if (!auth)
                return -ENOMEM;
@@ -948,41 +944,37 @@ 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_init(buf, TPM_BUFSIZE);
+       tpm_buf_reset(buf, 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, 
"TPM2_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;
@@ -1204,18 +1196,18 @@ 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(TPM_BUFSIZE, 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(TPM_BUFSIZE, 
GFP_KERNEL);
+       if (!template)
+               return -ENOMEM;
+
+       tpm_buf_init(buf, TPM_BUFSIZE);
+       tpm_buf_reset(buf, TPM2_ST_SESSIONS, TPM2_CC_CREATE_PRIMARY);
+       tpm_buf_init_sized(template, TPM_BUFSIZE);
 
        /*
         * create the template.  Note: in order for userspace to
@@ -1227,75 +1219,71 @@ 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,
-                             "attempting to create NULL primary");
+       rc = tpm_transmit_cmd(chip, buf, 0, "TPM2_CreatePrimary");
 
        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..cbf86ff5931f 100644
--- a/drivers/char/tpm/tpm2-space.c
+++ b/drivers/char/tpm/tpm2-space.c
@@ -71,24 +71,25 @@ 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(TPM_BUFSIZE, GFP_KERNEL);
+       if (!tbuf)
+               return -ENOMEM;
+
+       tpm_buf_init(tbuf, TPM_BUFSIZE);
+       tpm_buf_reset(tbuf, 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 +104,55 @@ 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(TPM_BUFSIZE, GFP_KERNEL);
+       if (!tbuf)
+               return -ENOMEM;
 
-       tpm_buf_append_u32(&tbuf, handle);
+       tpm_buf_init(tbuf, TPM_BUFSIZE);
+       tpm_buf_reset(tbuf, 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..682dfc93845d 100644
--- a/drivers/char/tpm/tpm_vtpm_proxy.c
+++ b/drivers/char/tpm/tpm_vtpm_proxy.c
@@ -395,40 +395,36 @@ 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(TPM_BUFSIZE, GFP_KERNEL);
+       if (!buf)
+               return -ENOMEM;
+
+       tpm_buf_init(buf, TPM_BUFSIZE);
        if (chip->flags & TPM_CHIP_FLAG_TPM2)
-               rc = tpm_buf_init(&buf, TPM2_ST_SESSIONS,
-                                 TPM2_CC_SET_LOCALITY);
+               tpm_buf_reset(buf, 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, 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 6d169c8976d8..e68995df8796 100644
--- a/include/linux/tpm.h
+++ b/include/linux/tpm.h
@@ -25,7 +25,8 @@
 #include <crypto/hash_info.h>
 #include <crypto/aes.h>
 
-#define TPM_DIGEST_SIZE 20     /* Max TPM v1.2 PCR size */
+#define TPM_DIGEST_SIZE                20      /* Max TPM v1.2 PCR size */
+#define TPM_BUFSIZE            4096
 
 /*
  * SHA-512 is, as of today, the largest digest in the TCG algorithm repository.
@@ -389,12 +390,14 @@ 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;
+       u16 length;
+       u16 capacity;
+       u8 data[];
 };
 
 enum tpm2_object_attributes {
@@ -425,12 +428,11 @@ struct tpm2_hash {
        unsigned int tpm_id;
 };
 
-int tpm_buf_init(struct tpm_buf *buf, u16 tag, u32 ordinal);
+void tpm_buf_init(struct tpm_buf *buf, u16 buf_size);
+void tpm_buf_init_sized(struct tpm_buf *buf, u16 buf_size);
 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);
-u32 tpm_buf_length(struct tpm_buf *buf);
+u16 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);
 void tpm_buf_append_u16(struct tpm_buf *buf, const u16 value);
diff --git a/security/keys/trusted-keys/trusted_tpm1.c 
b/security/keys/trusted-keys/trusted_tpm1.c
index 3d75bb6f9689..368e420c18af 100644
--- a/security/keys/trusted-keys/trusted_tpm1.c
+++ b/security/keys/trusted-keys/trusted_tpm1.c
@@ -320,9 +320,10 @@ static int TSS_checkhmac2(unsigned char *buffer,
  * For key specific tpm requests, we will generate and send our
  * own TPM command packets using the drivers send function.
  */
-static int trusted_tpm_send(unsigned char *cmd, size_t buflen)
+static int trusted_tpm_send(void *cmd, size_t cmd_len)
 {
-       struct tpm_buf buf;
+       u8 buf_data[512];
+       struct tpm_buf *buf = (struct tpm_buf *)buf_data;
        int rc;
 
        if (!chip)
@@ -332,11 +333,10 @@ static int trusted_tpm_send(unsigned char *cmd, size_t 
buflen)
        if (rc)
                return rc;
 
-       buf.flags = 0;
-       buf.length = buflen;
-       buf.data = cmd;
+       tpm_buf_init(buf, sizeof(buf_data));
+       tpm_buf_append(buf, cmd, cmd_len);
        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)
@@ -622,23 +622,23 @@ 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(TPM_BUFSIZE, GFP_KERNEL);
+       if (!tb)
+               return -ENOMEM;
+
+       tpm_buf_init(tb, TPM_BUFSIZE);
 
        /* 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;
 }
 
@@ -648,14 +648,15 @@ 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(TPM_BUFSIZE, GFP_KERNEL);
+       if (!tb)
+               return -ENOMEM;
+
+       tpm_buf_init(tb, TPM_BUFSIZE);
 
-       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);
@@ -663,7 +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 6fcff1066873..4d8d8705cbbc 100644
--- a/security/keys/trusted-keys/trusted_tpm2.c
+++ b/security/keys/trusted-keys/trusted_tpm2.c
@@ -205,7 +205,6 @@ int tpm2_seal_trusted(struct tpm_chip *chip,
 {
        u8 parent_name[TPM2_MAX_NAME_SIZE];
        off_t offset = TPM_HEADER_SIZE;
-       struct tpm_buf buf, sized;
        u16 parent_name_size;
        int blob_len = 0;
        int hash;
@@ -233,98 +232,100 @@ 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) {
+       struct tpm_buf *buf __free(kfree) = kzalloc(TPM_BUFSIZE, GFP_KERNEL);
+       if (!buf) {
+               rc = -ENOMEM;
                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_init(buf, TPM_BUFSIZE);
+       tpm_buf_reset(buf, TPM2_ST_SESSIONS, TPM2_CC_CREATE);
 
-       rc = tpm_buf_append_name(chip, &buf, options->keyhandle, parent_name,
+       rc = tpm_buf_append_name(chip, buf, options->keyhandle, parent_name,
                                 parent_name_size);
        if (rc)
-               goto out;
+               goto out_put;
 
-       tpm_buf_append_hmac_session(chip, &buf, TPM2_SA_DECRYPT,
+       tpm_buf_append_hmac_session(chip, buf, TPM2_SA_DECRYPT,
                                    options->keyauth, TPM_DIGEST_SIZE);
 
+       struct tpm_buf *sized __free(kfree) = kzalloc(TPM_BUFSIZE, GFP_KERNEL);
+       if (!sized) {
+               rc = -ENOMEM;
+               tpm2_end_auth_session(chip);
+               goto out_put;
+       }
+
        /* sensitive */
-       tpm_buf_append_u16(&sized, options->blobauth_len);
+       tpm_buf_init_sized(sized, TPM_BUFSIZE);
+       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_init_sized(sized, TPM_BUFSIZE);
+       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_INVALID) {
+       if (buf->flags & TPM_BUF_INVALID) {
                rc = -E2BIG;
                tpm2_end_auth_session(chip);
                goto out;
        }
 
-       rc = tpm_buf_fill_hmac_session(chip, &buf);
+       rc = tpm_buf_fill_hmac_session(chip, buf);
        if (rc)
                goto out;
 
-       rc = tpm_transmit_cmd(chip, &buf, 4, "sealing data");
-       rc = tpm_buf_check_hmac_response(chip, &buf, rc);
+       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_INVALID) {
+       blob_len = tpm_buf_read_u32(buf, &offset);
+       if (blob_len > MAX_BLOB_SIZE || buf->flags & TPM_BUF_INVALID) {
                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);
        if (blob_len < 0)
                rc = blob_len;
 
 out:
-       tpm_buf_destroy(&sized);
-       tpm_buf_destroy(&buf);
-
        if (!rc)
                payload->blob_len = blob_len;
 
@@ -356,7 +357,6 @@ static int tpm2_load_cmd(struct tpm_chip *chip,
                         u32 *blob_handle)
 {
        u8 *blob_ref __free(kfree) = NULL;
-       struct tpm_buf buf;
        unsigned int private_len;
        unsigned int public_len;
        unsigned int blob_len;
@@ -396,40 +396,39 @@ 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) {
+       struct tpm_buf *buf __free(kfree) = kzalloc(TPM_BUFSIZE, GFP_KERNEL);
+       if (!buf) {
                tpm2_end_auth_session(chip);
-               return rc;
+               return -ENOMEM;
        }
 
-       rc = tpm_buf_append_name(chip, &buf, options->keyhandle, parent_name,
+       tpm_buf_init(buf, TPM_BUFSIZE);
+       tpm_buf_reset(buf, TPM2_ST_SESSIONS, TPM2_CC_LOAD);
+
+       rc = tpm_buf_append_name(chip, buf, options->keyhandle, parent_name,
                                 parent_name_size);
        if (rc)
-               goto out;
+               return rc;
 
-       tpm_buf_append_hmac_session(chip, &buf, 0, options->keyauth,
+       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_INVALID) {
-               rc = -E2BIG;
+       if (buf->flags & TPM_BUF_INVALID) {
                tpm2_end_auth_session(chip);
-               goto out;
+               return -E2BIG;
        }
 
-       rc = tpm_buf_fill_hmac_session(chip, &buf);
+       rc = tpm_buf_fill_hmac_session(chip, buf);
        if (rc)
-               goto out;
+               return rc;
 
-       rc = tpm_transmit_cmd(chip, &buf, 4, "loading blob");
-       rc = tpm_buf_check_hmac_response(chip, &buf, rc);
+       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]);
-
-out:
-       tpm_buf_destroy(&buf);
+                       (__be32 *)&buf->data[TPM_HEADER_SIZE]);
 
        return tpm_ret_to_err(rc);
 }
@@ -454,28 +453,28 @@ static int tpm2_unseal_cmd(struct tpm_chip *chip,
                           u16 parent_name_size,
                           u32 blob_handle)
 {
-       struct tpm_buf buf;
        u16 data_len;
        u8 *data;
        int rc;
 
+       struct tpm_buf *buf __free(kfree) = kzalloc(TPM_BUFSIZE, 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_init(buf, TPM_BUFSIZE);
+       tpm_buf_reset(buf, TPM2_ST_SESSIONS, TPM2_CC_UNSEAL);
 
-       rc = tpm_buf_append_name(chip, &buf, options->keyhandle, parent_name,
+       rc = tpm_buf_append_name(chip, buf, options->keyhandle, parent_name,
                                 parent_name_size);
        if (rc)
-               goto out;
+               return rc;
 
        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 {
@@ -490,37 +489,33 @@ static int tpm2_unseal_cmd(struct tpm_chip *chip,
                 * could repeat our actions with the exfiltrated
                 * password.
                 */
-               tpm_buf_append_u32(&buf, 9 + options->blobauth_len);
-               tpm_buf_append_u32(&buf, options->policyhandle);
-               tpm_buf_append_u16(&buf, 0);
-               tpm_buf_append_u8(&buf, 0);
-               tpm_buf_append_u16(&buf, options->blobauth_len);
-               tpm_buf_append(&buf, options->blobauth, options->blobauth_len);
+               tpm_buf_append_u32(buf, 9 + options->blobauth_len);
+               tpm_buf_append_u32(buf, options->policyhandle);
+               tpm_buf_append_u16(buf, 0);
+               tpm_buf_append_u8(buf, 0);
+               tpm_buf_append_u16(buf, options->blobauth_len);
+               tpm_buf_append(buf, options->blobauth, options->blobauth_len);
 
                if (tpm2_chip_auth(chip))
-                       tpm_buf_append_hmac_session(chip, &buf, 
TPM2_SA_ENCRYPT, NULL, 0);
+                       tpm_buf_append_hmac_session(chip, buf, TPM2_SA_ENCRYPT, 
NULL, 0);
        }
 
-       rc = tpm_buf_fill_hmac_session(chip, &buf);
+       rc = tpm_buf_fill_hmac_session(chip, buf);
        if (rc)
-               goto out;
+               return rc;
 
-       rc = tpm_transmit_cmd(chip, &buf, 6, "unsealing");
-       rc = tpm_buf_check_hmac_response(chip, &buf, rc);
+       rc = tpm_transmit_cmd(chip, buf, 6, "unsealing");
+       rc = tpm_buf_check_hmac_response(chip, buf, rc);
 
        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 */
@@ -537,8 +532,6 @@ static int tpm2_unseal_cmd(struct tpm_chip *chip,
                }
        }
 
-out:
-       tpm_buf_destroy(&buf);
        return tpm_ret_to_err(rc);
 }
 
-- 
2.39.5


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