tpm_buf_append_name() has the following snippet in the beginning:

if (!tpm2_chip_auth(chip)) { tpm_buf_append_u32(buf, handle); /* count the number of handles in the upper bits of flags */ buf->handles++; return; }

The claim in the comment is wrong, and the comment is in the wrong place as alignment in this case should not anyway be a concern of the call site. In essence the comment is lying about the code, and thus needs to be adressed.

Further, 'handles' was incorrectly place to struct tpm_buf, as tpm-buf.c does manage its state. It is easy to grep that only piece of code that actually uses the field is tpm2-sessions.c.

Address the issues by moving the variable to struct tpm_chip.

Cc: stable@vger.kernel.org # v6.10+ Fixes: 699e3efd6c64 ("tpm: Add HMAC session start and end functions") Signed-off-by: Jarkko Sakkinen jarkko@kernel.org --- v2: * Was a bit more broken than I first thought, as 'handles' is only useful for tpm2-sessions.c and has zero relation to tpm-buf.c. --- drivers/char/tpm/tpm-buf.c | 1 - drivers/char/tpm/tpm2-sessions.c | 11 +++++------ include/linux/tpm.h | 8 ++++---- 3 files changed, 9 insertions(+), 11 deletions(-)

diff --git a/drivers/char/tpm/tpm-buf.c b/drivers/char/tpm/tpm-buf.c index cad0048bcc3c..d06e8e063151 100644 --- a/drivers/char/tpm/tpm-buf.c +++ b/drivers/char/tpm/tpm-buf.c @@ -44,7 +44,6 @@ 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->handles = 0; } EXPORT_SYMBOL_GPL(tpm_buf_reset);

diff --git a/drivers/char/tpm/tpm2-sessions.c b/drivers/char/tpm/tpm2-sessions.c index d3521aadd43e..a4ff5bca61dd 100644 --- a/drivers/char/tpm/tpm2-sessions.c +++ b/drivers/char/tpm/tpm2-sessions.c @@ -238,8 +238,7 @@ void tpm_buf_append_name(struct tpm_chip *chip, struct tpm_buf *buf,

if (!tpm2_chip_auth(chip)) { tpm_buf_append_u32(buf, handle); - /* count the number of handles in the upper bits of flags */ - buf->handles++; + chip->handles++; return; }

@@ -310,7 +309,7 @@ void tpm_buf_append_hmac_session(struct tpm_chip *chip, struct tpm_buf *buf,

if (!tpm2_chip_auth(chip)) { /* offset tells us where the sessions area begins */ - int offset = buf->handles * 4 + TPM_HEADER_SIZE; + int offset = chip->handles * 4 + TPM_HEADER_SIZE; u32 len = 9 + passphrase_len;

if (tpm_buf_length(buf) != offset) { @@ -1010,10 +1009,10 @@ int tpm2_start_auth_session(struct tpm_chip *chip)

tpm_buf_destroy(&buf);

- if (rc) - goto out; + if (!rc) + chip->handles = 0;

- out: +out: return rc; } EXPORT_SYMBOL(tpm2_start_auth_session); diff --git a/include/linux/tpm.h b/include/linux/tpm.h index e93ee8d936a9..b664f7556494 100644 --- a/include/linux/tpm.h +++ b/include/linux/tpm.h @@ -202,9 +202,9 @@ struct tpm_chip { /* active locality */ int locality;

+ /* handle count for session: */ + u8 handles; #ifdef CONFIG_TCG_TPM2_HMAC - /* details for communication security via sessions */ - /* saved context for NULL seed */ u8 null_key_context[TPM2_MAX_CONTEXT_SIZE]; /* name of NULL seed */ @@ -377,7 +377,6 @@ struct tpm_buf { u32 flags; u32 length; u8 *data; - u8 handles; };

enum tpm2_object_attributes { @@ -517,7 +516,7 @@ static inline void tpm_buf_append_hmac_session_opt(struct tpm_chip *chip, if (tpm2_chip_auth(chip)) { tpm_buf_append_hmac_session(chip, buf, attributes, passphrase, passphraselen); } else { - offset = buf->handles * 4 + TPM_HEADER_SIZE; + offset = chip->handles * 4 + TPM_HEADER_SIZE; head = (struct tpm_header *)buf->data;

/* @@ -541,6 +540,7 @@ void tpm2_end_auth_session(struct tpm_chip *chip);

static inline int tpm2_start_auth_session(struct tpm_chip *chip) { + chip->handles = 0; return 0; } static inline void tpm2_end_auth_session(struct tpm_chip *chip)