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[v9,6/8] tpm: tpm_tis: verify TPM_STS register is valid after locality request

Message ID 20200526141658.157801-7-amirmizi6@gmail.com (mailing list archive)
State Rejected, archived
Headers show
Series Add tpm i2c ptp driver | expand

Commit Message

Amir Mizinski May 26, 2020, 2:16 p.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(-)
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diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c
index 39b28a0..d9c9ff1 100644
--- a/drivers/char/tpm/tpm_tis_core.c
+++ b/drivers/char/tpm/tpm_tis_core.c
@@ -222,8 +222,14 @@  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 (wait_for_tpm_stat_result(chip, TPM_STS_GO,
+							     0, chip->timeout_c,
+							     &priv->int_queue,
+							     false) < 0)
+					return -ETIME;
 				return l;
+			}
 		} while (time_before(jiffies, stop));