diff --git a/drivers/char/tpm/tpm-buf.c b/drivers/char/tpm/tpm-buf.c
index 88ce1a5402de..8dc6b9db006b 100644
--- a/drivers/char/tpm/tpm-buf.c
+++ b/drivers/char/tpm/tpm-buf.c
@@ -18,6 +18,12 @@ int tpm_buf_init(struct tpm_buf *buf, u16 tag, u32 ordinal)
 }
 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)
 {
 	struct tpm_header *head = (struct tpm_header *)buf->data;
@@ -25,6 +31,8 @@ void tpm_buf_reset(struct tpm_buf *buf, u16 tag, u32 ordinal)
 	head->tag = cpu_to_be16(tag);
 	head->length = cpu_to_be32(sizeof(*head));
 	head->ordinal = cpu_to_be32(ordinal);
+
+	buf->length = sizeof(*head);
 }
 EXPORT_SYMBOL_GPL(tpm_buf_reset);
 
@@ -34,33 +42,41 @@ void tpm_buf_destroy(struct tpm_buf *buf)
 }
 EXPORT_SYMBOL_GPL(tpm_buf_destroy);
 
+/**
+ * tpm_buf_length() - Return the number of bytes consumed by the buffer
+ *
+ * Return: The number of bytes consumed by the buffer
+ */
 u32 tpm_buf_length(struct tpm_buf *buf)
 {
-	struct tpm_header *head = (struct tpm_header *)buf->data;
-
-	return be32_to_cpu(head->length);
+	return buf->length;
 }
 EXPORT_SYMBOL_GPL(tpm_buf_length);
 
-void tpm_buf_append(struct tpm_buf *buf,
-		    const unsigned char *new_data,
-		    unsigned int new_len)
+/**
+ * tpm_buf_append() - Append data to an initialized buffer
+ * @buf:	A &tpm_buf
+ * @new_data:	A data blob
+ * @new_length:	Size of the appended data
+ */
+
+void tpm_buf_append(struct tpm_buf *buf, const u8 *new_data, u16 new_length)
 {
 	struct tpm_header *head = (struct tpm_header *)buf->data;
-	u32 len = tpm_buf_length(buf);
 
 	/* Return silently if overflow has already happened. */
 	if (buf->flags & TPM_BUF_OVERFLOW)
 		return;
 
-	if ((len + new_len) > PAGE_SIZE) {
+	if ((buf->length + new_length) > PAGE_SIZE) {
 		WARN(1, "tpm_buf: overflow\n");
 		buf->flags |= TPM_BUF_OVERFLOW;
 		return;
 	}
 
-	memcpy(&buf->data[len], new_data, new_len);
-	head->length = cpu_to_be32(len + new_len);
+	memcpy(&buf->data[buf->length], new_data, new_length);
+	buf->length += new_length;
+	head->length = cpu_to_be32(buf->length);
 }
 EXPORT_SYMBOL_GPL(tpm_buf_append);
 
diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c
index 66b16d26eecc..492136214447 100644
--- a/drivers/char/tpm/tpm-interface.c
+++ b/drivers/char/tpm/tpm-interface.c
@@ -217,6 +217,9 @@ ssize_t tpm_transmit_cmd(struct tpm_chip *chip, struct tpm_buf *buf,
 	int err;
 	ssize_t len;
 
+	/* The recorded length is expected to match the command length: */
+	WARN_ON(buf->length != be32_to_cpu(header->length));
+
 	len = tpm_transmit(chip, buf->data, PAGE_SIZE);
 	if (len <  0)
 		return len;
@@ -232,6 +235,11 @@ ssize_t tpm_transmit_cmd(struct tpm_chip *chip, struct tpm_buf *buf,
 	if (len < min_rsp_body_length + TPM_HEADER_SIZE)
 		return -EFAULT;
 
+	buf->length = len;
+
+	/* The recorded length is expected to match the response length: */
+	WARN_ON(buf->length != be32_to_cpu(header->length));
+
 	return 0;
 }
 EXPORT_SYMBOL_GPL(tpm_transmit_cmd);
@@ -345,12 +353,12 @@ EXPORT_SYMBOL_GPL(tpm_pcr_extend);
 /**
  * tpm_send - send a TPM command
  * @chip:	a &struct tpm_chip instance, %NULL for the default chip
- * @cmd:	a TPM command buffer
- * @buflen:	the length of the TPM command buffer
+ * @data:	command blob
+ * @cmdlen:	length of the command
  *
  * Return: same as with tpm_transmit_cmd()
  */
-int tpm_send(struct tpm_chip *chip, void *cmd, size_t buflen)
+int tpm_send(struct tpm_chip *chip, void *data, size_t length)
 {
 	struct tpm_buf buf;
 	int rc;
@@ -359,7 +367,9 @@ int tpm_send(struct tpm_chip *chip, void *cmd, size_t buflen)
 	if (!chip)
 		return -ENODEV;
 
-	buf.data = cmd;
+	buf.flags = 0;
+	buf.length = length;
+	buf.data = data;
 	rc = tpm_transmit_cmd(chip, &buf, 0, "attempting to a send a command");
 
 	tpm_put_ops(chip);
diff --git a/include/linux/tpm.h b/include/linux/tpm.h
index 60032c60994b..3cfe2aeb1d9a 100644
--- a/include/linux/tpm.h
+++ b/include/linux/tpm.h
@@ -307,7 +307,8 @@ enum tpm_buf_flags {
 };
 
 struct tpm_buf {
-	unsigned int flags;
+	u32 flags;
+	u16 length;
 	u8 *data;
 };
 
@@ -331,8 +332,7 @@ int tpm_buf_init(struct tpm_buf *buf, u16 tag, u32 ordinal);
 void tpm_buf_reset(struct tpm_buf *buf, u16 tag, u32 ordinal);
 void tpm_buf_destroy(struct tpm_buf *buf);
 u32 tpm_buf_length(struct tpm_buf *buf);
-void tpm_buf_append(struct tpm_buf *buf, const unsigned char *new_data,
-		    unsigned int new_len);
+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);
 void tpm_buf_append_u32(struct tpm_buf *buf, const u32 value);
@@ -361,7 +361,7 @@ extern int tpm_pcr_read(struct tpm_chip *chip, u32 pcr_idx,
 			struct tpm_digest *digest);
 extern int tpm_pcr_extend(struct tpm_chip *chip, u32 pcr_idx,
 			  struct tpm_digest *digests);
-extern int tpm_send(struct tpm_chip *chip, void *cmd, size_t buflen);
+int tpm_send(struct tpm_chip *chip, void *data, size_t length);
 extern int tpm_get_random(struct tpm_chip *chip, u8 *data, size_t max);
 extern struct tpm_chip *tpm_default_chip(void);
 void tpm2_flush_context(struct tpm_chip *chip, u32 handle);
@@ -382,7 +382,7 @@ static inline int tpm_pcr_extend(struct tpm_chip *chip, u32 pcr_idx,
 	return -ENODEV;
 }
 
-static inline int tpm_send(struct tpm_chip *chip, void *cmd, size_t buflen)
+static inline int tpm_send(struct tpm_chip *chip, void *data, size_t length)
 {
 	return -ENODEV;
 }
diff --git a/security/keys/trusted-keys/trusted_tpm1.c b/security/keys/trusted-keys/trusted_tpm1.c
index aa108bea6739..7c1515014a5d 100644
--- a/security/keys/trusted-keys/trusted_tpm1.c
+++ b/security/keys/trusted-keys/trusted_tpm1.c
@@ -407,7 +407,7 @@ static int osap(struct tpm_buf *tb, struct osapsess *s,
 	tpm_buf_append_u32(tb, handle);
 	tpm_buf_append(tb, ononce, TPM_NONCE_SIZE);
 
-	ret = trusted_tpm_send(tb->data, MAX_BUF_SIZE);
+	ret = trusted_tpm_send(tb->data, tb->length);
 	if (ret < 0)
 		return ret;
 
@@ -431,7 +431,7 @@ int oiap(struct tpm_buf *tb, uint32_t *handle, unsigned char *nonce)
 		return -ENODEV;
 
 	tpm_buf_reset(tb, TPM_TAG_RQU_COMMAND, TPM_ORD_OIAP);
-	ret = trusted_tpm_send(tb->data, MAX_BUF_SIZE);
+	ret = trusted_tpm_send(tb->data, tb->length);
 	if (ret < 0)
 		return ret;
 
@@ -543,7 +543,7 @@ static int tpm_seal(struct tpm_buf *tb, uint16_t keytype,
 	tpm_buf_append_u8(tb, cont);
 	tpm_buf_append(tb, td->pubauth, SHA1_DIGEST_SIZE);
 
-	ret = trusted_tpm_send(tb->data, MAX_BUF_SIZE);
+	ret = trusted_tpm_send(tb->data, tb->length);
 	if (ret < 0)
 		goto out;
 
@@ -634,7 +634,7 @@ static int tpm_unseal(struct tpm_buf *tb,
 	tpm_buf_append_u8(tb, cont);
 	tpm_buf_append(tb, authdata2, SHA1_DIGEST_SIZE);
 
-	ret = trusted_tpm_send(tb->data, MAX_BUF_SIZE);
+	ret = trusted_tpm_send(tb->data, tb->length);
 	if (ret < 0) {
 		pr_info("authhmac failed (%d)\n", ret);
 		return ret;
