diff mbox series

[v13,5/7] tpm: tpm_tis: verify TPM_STS register is valid after locality request

Message ID 20210826111908.117278-6-amirmizi6@gmail.com (mailing list archive)
State New, archived
Headers show
Series Add tpm i2c ptp driver | expand

Commit Message

Amir Mizinski Aug. 26, 2021, 11:19 a.m. UTC 
From: Amir Mizinski <amirmizi6@gmail.com>

Issue could result when the TPM does not update TPM_STS register after
a locality request (TPM_STS Initial value = 0xFF) and a TPM_STS register
read occurs (tpm_tis_status(chip)).

Checking the next condition("if ((status & TPM_STS_COMMAND_READY) == 0)"),
the status will be at 0xFF and will be considered, wrongly, in "Ready"
state (by checking only one bit). However, at this moment the TPM is, in
fact, in "Idle" state and remains in "Idle" state because
"tpm_tis_ready(chip);" was not executed.

Suggested-by: Benoit Houyere <benoit.houyere@st.com>
Signed-off-by: Amir Mizinski <amirmizi6@gmail.com>
---
 drivers/char/tpm/tpm_tis_core.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

Comments

Jarkko Sakkinen Aug. 26, 2021, 4:03 p.m. UTC | #1 
On Thu, 2021-08-26 at 14:19 +0300, amirmizi6@gmail.com wrote:
> From: Amir Mizinski <amirmizi6@gmail.com>
> 
> Issue could result when the TPM does not update TPM_STS register after
> a locality request (TPM_STS Initial value = 0xFF) and a TPM_STS register
> read occurs (tpm_tis_status(chip)).

What does it mean when "issue results"?

I don't understand that part.

/Jarkko
diff mbox series

Patch

diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c
index 4145758..d527c43 100644
--- a/drivers/char/tpm/tpm_tis_core.c
+++ b/drivers/char/tpm/tpm_tis_core.c
@@ -177,8 +177,14 @@  static int request_locality(struct tpm_chip *chip, int l)
 	} else {
 		/* wait for burstcount */
 		do {
-			if (check_locality(chip, l))
+			if (check_locality(chip, l)) {
+				if (tpm_tis_wait_for_stat(chip, TPM_STS_GO, 0,
+							  chip->timeout_c,
+							  &priv->int_queue,
+							  false) < 0)
+					return -ETIME;
 				return l;
+			}
 			tpm_msleep(TPM_TIMEOUT);
 		} while (time_before(jiffies, stop));
 	}