[PATCH v4] tpm: Add check for Failure mode for TPM2 modules

["Mårten Lindahl" <marten.lindahl@axis.com>]

In commit 0aa698787aa2 ("tpm: Add Upgrade/Reduced mode support for
TPM2 modules") it was said that:

"If the TPM is in Failure mode, it will successfully respond to both
tpm2_do_selftest() and tpm2_startup() calls. Although, will fail to
answer to tpm2_get_cc_attrs_tbl(). Use this fact to conclude that TPM
is in Failure mode."

But a check was never added in the commit when calling
tpm2_get_cc_attrs_tbl() to conclude that the TPM is in Failure mode.
This commit corrects this by adding a check.

Fixes: 0aa698787aa2 ("tpm: Add Upgrade/Reduced mode support for TPM2 modules")
Cc: stable@vger.kernel.org # v5.17+
Signed-off-by: Mårten Lindahl <marten.lindahl@axis.com>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
---

v4:
 - Resend of patch because of invalid characters in Signed-off-by tag.

v3:
 - Add Jarkkos Reviewed-by tag.
 - Add Fixes tag and Cc.

v2:
 - Add missed check for TPM error code.

 drivers/char/tpm/tpm2-cmd.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c
index c1eb5d223839..65d03867e114 100644
--- a/drivers/char/tpm/tpm2-cmd.c
+++ b/drivers/char/tpm/tpm2-cmd.c
@@ -752,6 +752,12 @@ int tpm2_auto_startup(struct tpm_chip *chip)
 	}
 
 	rc = tpm2_get_cc_attrs_tbl(chip);
+	if (rc == TPM2_RC_FAILURE || (rc < 0 && rc != -ENOMEM)) {
+		dev_info(&chip->dev,
+			 "TPM in field failure mode, requires firmware upgrade\n");
+		chip->flags |= TPM_CHIP_FLAG_FIRMWARE_UPGRADE;
+		rc = 0;
+	}
 
 out:
 	/*
-- 
2.30.2