Re: [PATCH] tpm: Check non-nullity of chip->auth

On 7/1/24 13:07, Jarkko Sakkinen wrote:

All exported functions lack the check for non-nullity of chip->auth. Add the guard for each.

Link: https://lore.kernel.org/linux-integrity/9f86a167074d9b522311715c567f1c19b88e... Cc: Stefan Berger stefanb@linux.ibm.com Cc: stable@vger.kernel.org Cc: linux-kernel@vger.kernel.org Fixes: 1085b8276bb4 ("tpm: Add the rest of the session HMAC API") Signed-off-by: Jarkko Sakkinen jarkko@kernel.org

---

drivers/char/tpm/tpm2-sessions.c | 26 ++++++++++++++++++++++++-- 1 file changed, 24 insertions(+), 2 deletions(-)

diff --git a/drivers/char/tpm/tpm2-sessions.c b/drivers/char/tpm/tpm2-sessions.c index 907ac9956a78..d833db20531a 100644 --- a/drivers/char/tpm/tpm2-sessions.c +++ b/drivers/char/tpm/tpm2-sessions.c @@ -377,6 +377,9 @@ void tpm_buf_append_hmac_session(struct tpm_chip *chip, struct tpm_buf *buf, u32 len; struct tpm2_auth *auth = chip->auth;

• if (!auth)

• return;
  

• /*
  • The Architecture Guide requires us to strip trailing zeros
  • before computing the HMAC

@@ -449,6 +452,9 @@ void tpm_buf_fill_hmac_session(struct tpm_chip *chip, struct tpm_buf *buf) u8 cphash[SHA256_DIGEST_SIZE]; struct sha256_state sctx;

• if (!auth)

• return;
  

• /* save the command code in BE format */ auth->ordinal = head->ordinal;

@@ -639,6 +645,9 @@ void tpm_buf_append_name(struct tpm_chip *chip, struct tpm_buf *buf, struct tpm2_auth *auth = chip->auth; int slot;

• if (!auth)

• return;
  

• slot = (tpm_buf_length(buf) - TPM_HEADER_SIZE)/4; if (slot >= AUTH_MAX_NAMES) { dev_err(&chip->dev, "TPM: too many handles\n");

@@ -705,6 +714,9 @@ int tpm_buf_check_hmac_response(struct tpm_chip *chip, struct tpm_buf *buf, u32 cc = be32_to_cpu(auth->ordinal); int parm_len, len, i, handles;

• if (!auth)

• return rc;
  

• if (auth->session >= TPM_HEADER_SIZE) { WARN(1, "tpm session not filled correctly\n"); goto out;

@@ -824,8 +836,13 @@ EXPORT_SYMBOL(tpm_buf_check_hmac_response); */ void tpm2_end_auth_session(struct tpm_chip *chip) {

• tpm2_flush_context(chip, chip->auth->handle);
• memzero_explicit(chip->auth, sizeof(*chip->auth));

• struct tpm2_auth *auth = chip->auth;
• if (!auth)

• return;
  

• tpm2_flush_context(chip, auth->handle);
• memzero_explicit(auth, sizeof(*auth)); } EXPORT_SYMBOL(tpm2_end_auth_session);

@@ -907,6 +924,11 @@ int tpm2_start_auth_session(struct tpm_chip *chip) int rc; u32 null_key;

• if (!auth) {

• pr_warn_once("%s: encryption is not active\n", __func__);
  

• return 0;
  

• }
• rc = tpm2_load_null(chip, &null_key); if (rc) goto out;

It looks like you got all of the chip->auth tested:

Reviewed-by: Stefan Berger stefanb@linux.ibm.com

As I mentioned in the other email (1), it does not solve the problem on ppc64.

1: https://lore.kernel.org/linux-integrity/656b319fc58683e399323b880722434467cf...