[PATCH 6.12 505/567] tpm2-sessions: Fix tpm2_read_public range checks

Greg Kroah-Hartman
2026-01-06T17:42:10Z

From: Jarkko Sakkinen <jarkko@kernel.org>

[ Upstream commit bda1cbf73c6e241267c286427f2ed52b5735d872 ]

tpm2_read_public() has some rudimentary range checks but the function does
not ensure that the response buffer has enough bytes for the full TPMT_HA
payload.

Re-implement the function with necessary checks and validation, and return
name and name size for all handle types back to the caller.

Cc: stable@vger.kernel.org # v6.10+
Fixes: d0a25bb961e6 ("tpm: Add HMAC session name/handle append")
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
Reviewed-by: Jonathan McDowell <noodles@meta.com>
[ different semantics around u8 name_size() ]
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/char/tpm/tpm2-cmd.c | 3 +
drivers/char/tpm/tpm2-sessions.c | 85 ++++++++++++++++++++++++---------------
2 files changed, 56 insertions(+), 32 deletions(-)

--- a/drivers/char/tpm/tpm2-cmd.c
+++ b/drivers/char/tpm/tpm2-cmd.c
@@ -11,8 +11,11 @@
* used by the kernel internally.
*/

+#include "linux/dev_printk.h"
+#include "linux/tpm.h"
#include "tpm.h"
#include <crypto/hash_info.h>
+#include <linux/unaligned.h>

static bool disable_pcr_integrity;
module_param(disable_pcr_integrity, bool, 0444);
--- a/drivers/char/tpm/tpm2-sessions.c
+++ b/drivers/char/tpm/tpm2-sessions.c
@@ -156,47 +156,60 @@ static u8 name_size(const u8 *name)
return size_map[alg] + 2;
}

-static int tpm2_parse_read_public(char *name, struct tpm_buf *buf)
+static int tpm2_read_public(struct tpm_chip *chip, u32 handle, void *name)
{
- struct tpm_header *head = (struct tpm_header *)buf->data;
+ u32 mso = tpm2_handle_mso(handle);
off_t offset = TPM_HEADER_SIZE;
- u32 tot_len = be32_to_cpu(head->length);
- u32 val;
-
- /* we're starting after the header so adjust the length */
- tot_len -= TPM_HEADER_SIZE;
-
- /* skip public */
- val = tpm_buf_read_u16(buf, &offset);
- if (val > tot_len)
- return -EINVAL;
- offset += val;
- /* name */
- val = tpm_buf_read_u16(buf, &offset);
- if (val != name_size(&buf->data[offset]))
- return -EINVAL;
- memcpy(name, &buf->data[offset], val);
- /* forget the rest */
- return 0;
-}
-
-static int tpm2_read_public(struct tpm_chip *chip, u32 handle, char *name)
-{
- struct tpm_buf buf;
int rc;
+ u8 name_size_alg;
+ struct tpm_buf buf;
+
+ if (mso != TPM2_MSO_PERSISTENT && mso != TPM2_MSO_VOLATILE &&
+ mso != TPM2_MSO_NVRAM) {
+ memcpy(name, &handle, sizeof(u32));
+ return sizeof(u32);
+ }

rc = tpm_buf_init(&buf, TPM2_ST_NO_SESSIONS, TPM2_CC_READ_PUBLIC);
if (rc)
return rc;

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 = tpm_transmit_cmd(chip, &buf, 0, "TPM2_ReadPublic");
+ if (rc) {
+ tpm_buf_destroy(&buf);
+ return tpm_ret_to_err(rc);
+ }

- return rc;
+ /* Skip TPMT_PUBLIC: */
+ 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);
+ return -EIO;
+ }
+
+ rc = tpm_buf_read_u16(&buf, &offset);
+ name_size_alg = name_size(&buf.data[offset]);
+
+ if (rc != name_size_alg) {
+ tpm_buf_destroy(&buf);
+ return -EIO;
+ }
+
+ if (offset + rc > tpm_buf_length(&buf)) {
+ tpm_buf_destroy(&buf);
+ return -EIO;
+ }
+
+ memcpy(name, &buf.data[offset], rc);
+ tpm_buf_destroy(&buf);
+ return name_size_alg;
}
#endif /* CONFIG_TCG_TPM2_HMAC */

@@ -229,6 +242,7 @@ void tpm_buf_append_name(struct tpm_chip
enum tpm2_mso_type mso = tpm2_handle_mso(handle);
struct tpm2_auth *auth;
int slot;
+ int ret;
#endif

if (!tpm2_chip_auth(chip)) {
@@ -251,8 +265,11 @@ void tpm_buf_append_name(struct tpm_chip
if (mso == TPM2_MSO_PERSISTENT ||
mso == TPM2_MSO_VOLATILE ||
mso == TPM2_MSO_NVRAM) {
- if (!name)
- tpm2_read_public(chip, handle, auth->name[slot]);
+ if (!name) {
+ ret = tpm2_read_public(chip, handle, auth->name[slot]);
+ if (ret < 0)
+ goto err;
+ }
} else {
if (name)
dev_err(&chip->dev, "TPM: Handle does not require name but one is specified\n");
@@ -261,6 +278,10 @@ void tpm_buf_append_name(struct tpm_chip
auth->name_h[slot] = handle;
if (name)
memcpy(auth->name[slot], name, name_size(name));
+ return;
+
+err:
+ tpm2_end_auth_session(chip);
#endif
}
EXPORT_SYMBOL_GPL(tpm_buf_append_name);